31st August 2014 10:00 pm

Django Blog Tutorial - the Next Generation - Part 8

Hello again! In our final instalment, we’ll wrap up our blog by:

• Implementing a sitemap
• Optimising and tidying up the site
• Creating a Fabric task for easier deployment

I’ll also cover development tools and practices that can make using Django easier. But first there’s a few housekeeping tasks that need doing…

Don’t forget to activate your virtualenv - you should know how to do this off by heart by now!

Upgrading Django

At the time of writing, Django 1.7 is due any day now, but it’s not out yet so I won’t cover it. The biggest change is the addition of a built-in migration system, but switching from South to this is well-documented. When Django 1.7 comes out, it shouldn’t be difficult to upgrade to it - because we have good test coverage, we shouldn’t have much trouble catching errors.

However, Django 1.6.6 was recently released, and we need to upgrade to it. Just enter the following command to upgrade:

$ pip install Django --upgrade

Then add it to your requirements.txt:

$ pip freeze > requirements.txt

Then commit your changes:

$ git add requirements.txt
$ git commit -m 'Upgraded Django version'

Implementing a sitemap

Creating a sitemap for your blog is a good idea - it can be submitted to search engines, so that they can easily find your content. With Django, it’s pretty straightforward too.

First, let’s create a test for our sitemap. Add the following code at the end of tests.py:

class SitemapTest(BaseAcceptanceTest):
    def test_sitemap(self):
        # Create a post
        post = PostFactory()
        # Create a flat page
        page = FlatPageFactory()
        # Get sitemap
        response = self.client.get('/sitemap.xml')
        self.assertEquals(response.status_code, 200)
        # Check post is present in sitemap
        self.assertTrue('my-first-post' in response.content)
        # Check page is present in sitemap
        self.assertTrue('/about/' in response.content)

Run it, and you should see the test fail:

$ python manage.py test blogengine
Creating test database for alias 'default'...
...........................F
======================================================================
FAIL: test_sitemap (blogengine.tests.SitemapTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 847, in test_sitemap
    self.assertEquals(response.status_code, 200)
AssertionError: 404 != 200
----------------------------------------------------------------------
Ran 28 tests in 6.873s
FAILED (failures=1)
Destroying test database for alias 'default'...

Now, let’s implement our sitemap. The sitemap application comes with Django, and needs to be activated in your settings file, under INSTALLED_APPS:

    'django.contrib.sitemaps',

Next, let’s think about what content we want to include in the sitemap. We want to index our flat pages and our blog posts, so our sitemap should reflect that. Create a new file at blogengine/sitemap.py and enter the following text:

from django.contrib.sitemaps import Sitemap
from django.contrib.flatpages.models import FlatPage
from blogengine.models import Post
class PostSitemap(Sitemap):
    changefreq = "always"
    priority = 0.5
    def items(self):
        return Post.objects.all()
    def lastmod(self, obj):
        return obj.pub_date
class FlatpageSitemap(Sitemap):
    changefreq = "always"
    priority = 0.5
    def items(self):
        return FlatPage.objects.all()

We define two sitemaps, one for all the posts, and the other for all the flat pages. Note that this works in a very similar way to the syndication framework.

Next, we amend our URLs. Add the following text after the existing imports in your URL file:

from django.contrib.sitemaps.views import sitemap
from blogengine.sitemap import PostSitemap, FlatpageSitemap
# Define sitemaps
sitemaps = {
    'posts': PostSitemap,
    'pages': FlatpageSitemap
}

Then add the following after the existing routes:

    # Sitemap
    url(r'^sitemap\.xml$', sitemap, {'sitemaps': sitemaps},
            name='django.contrib.sitemaps.views.sitemap'),

Here we define what sitemaps we’re going to use, and we define a URL for them. It’s pretty straightforward to use.

Let’s run our tests:

$ python manage.py test blogengine
Creating test database for alias 'default'...
............................
----------------------------------------------------------------------
Ran 28 tests in 6.863s
OK
Destroying test database for alias 'default'...

And done! Let’s commit our changes:

$ git add blogengine/ django_tutorial_blog_ng/settings.py
$ git commit -m 'Implemented a sitemap'

Fixing test coverage

Our blog is now feature-complete, but there are a few gaps in test coverage, so we’ll fix them. If, like me, you’re using Coveralls.io, you can easily see via their web interface where there are gaps in the coverage.

Now, our gaps are all in our view file - if you take a look at my build, you can easily identify the gaps as they’re marked in red.

The first gap is where a tag does not exist. Interestingly, if we look at the code in the view, we can see that some of it is redundant:

class TagPostsFeed(PostsFeed):
    def get_object(self, request, slug):
        return get_object_or_404(Tag, slug=slug)
    def title(self, obj):
        return "RSS feed - blog posts tagged  %s" % obj.name
    def link(self, obj):
        return obj.get_absolute_url()
    def description(self, obj):
        return "RSS feed - blog posts tagged %s" % obj.name
    def items(self, obj):
        try:
            tag = Tag.objects.get(slug=obj.slug)
            return tag.post_set.all()
        except Tag.DoesNotExist:
            return Post.objects.none()

Under the items function, we check to see if the tag exists. However, under get_object we can see that if the object didn’t exist, it would already have returned a 404 error. We can therefore safely amend items to not check, since that try statement will never fail:

class TagPostsFeed(PostsFeed):
    def get_object(self, request, slug):
        return get_object_or_404(Tag, slug=slug)
    def title(self, obj):
        return "RSS feed - blog posts tagged  %s" % obj.name
    def link(self, obj):
        return obj.get_absolute_url()
    def description(self, obj):
        return "RSS feed - blog posts tagged %s" % obj.name
    def items(self, obj):
        tag = Tag.objects.get(slug=obj.slug)
        return tag.post_set.all()

The other two gaps are in our search view - we never get an empty result for the search in the following section:

def getSearchResults(request):
    """
    Search for a post by title or text
    """
    # Get the query data
    query = request.GET.get('q', '')
    page = request.GET.get('page', 1)
    # Query the database
    if query:
        results = Post.objects.filter(Q(text__icontains=query) | Q(title__icontains=query))
    else:
        results = None
    # Add pagination
    pages = Paginator(results, 5)
    # Get specified page
    try:
        returned_page = pages.page(page)
    except EmptyPage:
        returned_page = pages.page(pages.num_pages)
    # Display the search results
    return render_to_response('blogengine/search_post_list.html',
                              {'page_obj': returned_page,
                               'object_list': returned_page.object_list,
                               'search': query})

So replace it with this:

def getSearchResults(request):
    """
    Search for a post by title or text
    """
    # Get the query data
    query = request.GET.get('q', '')
    page = request.GET.get('page', 1)
    # Query the database
    results = Post.objects.filter(Q(text__icontains=query) | Q(title__icontains=query))
    # Add pagination
    pages = Paginator(results, 5)
    # Get specified page
    try:
        returned_page = pages.page(page)
    except EmptyPage:
        returned_page = pages.page(pages.num_pages)
    # Display the search results
    return render_to_response('blogengine/search_post_list.html',
                              {'page_obj': returned_page,
                               'object_list': returned_page.object_list,
                               'search': query})

We don’t need to check whether query is defined because if q is left blank, the value of query will be an empty string, so we may as well pull out the redundant code.

Finally, the other gap is for when a user tries to get an empty search page (eg, page two of something with five or less results). So let’s add another test to our SearchViewTest class:

    def test_failing_search(self):
        # Search for something that is not present
        response = self.client.get('/search?q=wibble')
        self.assertEquals(response.status_code, 200)
        self.assertTrue('No posts found' in response.content)
        # Try to get nonexistent second page
        response = self.client.get('/search?q=wibble&page=2')
        self.assertEquals(response.status_code, 200)
        self.assertTrue('No posts found' in response.content)

Run our tests and check the coverage:

$ coverage run --include="blogengine/*" --omit="blogengine/migrations/*" manage.py test blogengine
$ coverage html

If you open htmlcov/index.html in your browser, you should see that the test coverage is back up to 100%. With that done, it’s time to commit again:

$ git add blogengine/
$ git commit -m 'Fixed gaps in coverage'

Remember, it’s not always possible to achieve 100% test coverage, and you shouldn’t worry too much about it if it’s not possible - it’s possible to ignore code if necessary. However, it’s a good idea to aim for 100%.

Using Fabric for deployment

Next we’ll cover using Fabric, a handy tool for deploying your changes (any pretty much any other task you want to automate). First, you need to install it:

$ pip install Fabric

If you have any problems installing it, you should be able to resolve them via Google - most of them are likely to be absent libraries that Fabric depends upon. Once it’s installed, add it to your requirements.tzt:

$ pip freeze > requirements.txt

Next, create a file called fabfile.py and enter the following text:

#!/usr/bin/env python
from fabric.api import local
def deploy():
    """
    Deploy the latest version to Heroku
    """
    # Push changes to master
    local("git push origin master")
    # Push changes to Heroku
    local("git push heroku master")
    # Run migrations on Heroku
    local("heroku run python manage.py migrate")

Now, all this file does is push our changes to Github (or wherever else your repository is hosted) and to Heroku, and runs your migrations. It’s not a terribly big task anyway, but it’s handy to have it in place. Let’s commit our changes:

$ git add fabfile.py requirements.txt
$ git commit -m 'Added Fabric task for deployment'

Then, let’s try it out:

$ fab deploy

There, wasn’t that more convenient? Fabric is much more powerful than this simple demonstration indicates, and can run tasks on remote servers via SSH easily. I recommend you take a look at the documentation to see what else you can do with it. If you’re hosting your site on a VPS, you will probably find Fabric indispensable, as you will need to restart the application every time you push up a new revision.

Tidying up

We want our blog application to play nicely with other Django apps. For instance, say you’re working on a new site that includes a blogging engine. Wouldn’t it make sense to just be able to drop in this blogging engine and have it work immediately? At the moment, some of our URL’s are hard-coded, so we may have problems in doing so. Let’s fix that.

First we’ll amend our tests. Add this at the top of the tests file:

from django.core.urlresolvers import reverse

Next, replace every instance of this:

        response = self.client.get('/')

with this:

response = self.client.get(reverse('blogengine:index'))

Then, rewrite the calls to the search route. For instance, this:

        response = self.client.get('/search?q=first')

should become this:

        response = self.client.get(reverse('blogengine:search') + '?q=first')

I’ll leave changing these as an exercise for the reader, but check the repository if you get stuck.

Next, we need to assign a namespace to our app’s routes:

from django.conf.urls import patterns, include, url
from django.contrib import admin
admin.autodiscover()
urlpatterns = patterns('',
    # Examples:
    # url(r'^$', 'django_tutorial_blog_ng.views.home', name='home'),
    # url(r'^blog/', include('blog.urls')),
    url(r'^admin/', include(admin.site.urls)),
    # Blog URLs
    url(r'', include('blogengine.urls', namespace="blogengine")),
    # Flat pages
    url(r'', include('django.contrib.flatpages.urls')),
)

We then assign names to our routes in the app’s urls.py:

from django.conf.urls import patterns, url
from django.views.generic import ListView, DetailView
from blogengine.models import Post, Category, Tag
from blogengine.views import CategoryListView, TagListView, PostsFeed, CategoryPostsFeed, TagPostsFeed, getSearchResults
from django.contrib.sitemaps.views import sitemap
from blogengine.sitemap import PostSitemap, FlatpageSitemap
# Define sitemaps
sitemaps = {
    'posts': PostSitemap,
    'pages': FlatpageSitemap
}
urlpatterns = patterns('',
    # Index
    url(r'^(?P<page>\d+)?/?$', ListView.as_view(
        model=Post,
        paginate_by=5,
        ),
        name='index'
        ),
    # Individual posts
    url(r'^(?P<pub_date__year>\d{4})/(?P<pub_date__month>\d{1,2})/(?P<slug>[a-zA-Z0-9-]+)/?$', DetailView.as_view(
        model=Post,
        ),
        name='post'
        ),
    # Categories
    url(r'^category/(?P<slug>[a-zA-Z0-9-]+)/?$', CategoryListView.as_view(
        paginate_by=5,
        model=Category,
        ),
        name='category'
        ),
    # Tags
    url(r'^tag/(?P<slug>[a-zA-Z0-9-]+)/?$', TagListView.as_view(
        paginate_by=5,
        model=Tag,
        ),
        name='tag'
        ),
    # Post RSS feed
    url(r'^feeds/posts/$', PostsFeed()),
    # Category RSS feed
    url(r'^feeds/posts/category/(?P<slug>[a-zA-Z0-9-]+)/?$', CategoryPostsFeed()),
    # Tag RSS feed
    url(r'^feeds/posts/tag/(?P<slug>[a-zA-Z0-9-]+)/?$', TagPostsFeed()),
    # Search posts
    url(r'^search', getSearchResults, name='search'),
    # Sitemap
    url(r'^sitemap\.xml$', sitemap, {'sitemaps': sitemaps},
            name='django.contrib.sitemaps.views.sitemap'),
)

You also need to amend two of your templates:

<!DOCTYPE html>
<!--[if lt IE 7]>      <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>         <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>         <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js"> <!--<![endif]-->
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <title>{% block title %}My Django Blog{% endblock %}</title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link rel="alternate" type="application/rss+xml" title="Blog posts" href="/feeds/posts/" >
        <!-- Place favicon.ico and apple-touch-icon.png in the root directory -->
        {% load staticfiles %}
        <link rel="stylesheet" href="{% static 'bower_components/html5-boilerplate/css/normalize.css' %}">
        <link rel="stylesheet" href="{% static 'bower_components/html5-boilerplate/css/main.css' %}">
        <link rel="stylesheet" href="{% static 'bower_components/bootstrap/dist/css/bootstrap.min.css' %}">
        <link rel="stylesheet" href="{% static 'bower_components/bootstrap/dist/css/bootstrap-theme.min.css' %}">
        <link rel="stylesheet" href="{% static 'css/main.css' %}">
        <link rel="stylesheet" href="{% static 'css/code.css' %}">
        <script src="{% static 'bower_components/html5-boilerplate/js/vendor/modernizr-2.6.2.min.js' %}"></script>
    </head>
    <body>
        <!--[if lt IE 7]>
            <p class="browsehappy">You are using an <strong>outdated</strong> browser. Please <a href="http://browsehappy.com/">upgrade your browser</a> to improve your experience.</p>
        <![endif]-->
        <!-- Add your site or application content here -->
        <div id="fb-root"></div>
        <script>(function(d, s, id) {
            var js, fjs = d.getElementsByTagName(s)[0];
            if (d.getElementById(id)) return;
                js = d.createElement(s); js.id = id;
                js.src = "//connect.facebook.net/en_GB/all.js#xfbml=1";
                fjs.parentNode.insertBefore(js, fjs);
            }(document, 'script', 'facebook-jssdk'));</script>
        <div class="navbar navbar-static-top navbar-inverse">
            <div class="container-fluid">
                <div class="navbar-header">
                    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#header-nav">
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                    </button>
                    <a class="navbar-brand" href="{% url 'blogengine:index' %}">My Django Blog</a>
                </div>
                <div class="collapse navbar-collapse" id="header-nav">
                    <ul class="nav navbar-nav">
                        {% load flatpages %}
                        {% get_flatpages as flatpages %}
                        {% for flatpage in flatpages %}
                        <li><a href="{{ flatpage.url }}">{{ flatpage.title }}</a></li>
                        {% endfor %}
                        <li><a href="/feeds/posts/">RSS feed</a></li>
                        <form action="/search" method="GET" class="navbar-form navbar-left">
                            <div class="form-group">
                                <input type="text" name="q" placeholder="Search..." class="form-control"></input>
                            </div>
                            <button type="submit" class="btn btn-default">Search</button>
                        </form>
                    </ul>
                </div>
            </div>
        </div>
        <div class="container">
            {% block header %}
                <div class="page-header">
                    <h1>My Django Blog</h1>
                </div>
            {% endblock %}
            <div class="row">
                {% block content %}{% endblock %}
            </div>
        </div>
        <div class="container footer">
            <div class="row">
                <div class="span12">
                    <p>Copyright &copy; {% now "Y" %}</p>
                </div>
            </div>
        </div>
        <script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
        <script>window.jQuery || document.write('<script src="{% static 'bower_components/html5-boilerplate/js/vendor/jquery-1.10.2.min.js' %}"><\/script>')</script>
        <script src="{% static 'bower_components/html5-boilerplate/js/plugins.js' %}"></script>
        <script src="{% static 'bower_components/bootstrap/dist/js/bootstrap.min.js' %}"></script>
        <!-- Google Analytics: change UA-XXXXX-X to be your site's ID. -->
        <script>
            (function(b,o,i,l,e,r){b.GoogleAnalyticsObject=l;b[l]||(b[l]=
            function(){(b[l].q=b[l].q||[]).push(arguments)});b[l].l=+new Date;
            e=o.createElement(i);r=o.getElementsByTagName(i)[0];
            e.src='//www.google-analytics.com/analytics.js';
            r.parentNode.insertBefore(e,r)}(window,document,'script','ga'));
            ga('create','UA-XXXXX-X');ga('send','pageview');
        </script>
    </body>
</html>

{% extends "blogengine/includes/base.html" %}
    {% load custom_markdown %}
    {% block content %}
        {% if object_list %}
            {% for post in object_list %}
            <div class="post col-md-12">
            <h1><a href="{{ post.get_absolute_url }}">{{ post.title }}</a></h1>
            <h3>{{ post.pub_date }}</h3>
            {{ post.text|custom_markdown }}
            </div>
            {% if post.category %}
            <div class="col-md-12">
            <a href="{{ post.category.get_absolute_url }}"><span class="label label-primary">{{ post.category.name }}</span></a>
            </div>
            {% endif %}
            {% if post.tags %}
            <div class="col-md-12">
            {% for tag in post.tags.all %}
            <a href="{{ tag.get_absolute_url }}"><span class="label label-success">{{ tag.name }}</span></a>
            {% endfor %}
            </div>
            {% endif %}
            {% endfor %}
        {% else %}
            <p>No posts found</p>
        {% endif %}
        <ul class="pager">
        {% if page_obj.has_previous %}
        <li class="previous"><a href="{% url 'blogengine:search' %}?page={{ page_obj.previous_page_number }}&q={{ search }}">Previous Page</a></li>
        {% endif %}
        {% if page_obj.has_next %}
        <li class="next"><a href="{% url 'blogengine:search' %}?page={{ page_obj.next_page_number }}&q={{ search }}">Next Page</a></li>
        {% endif %}
        </ul>
    {% endblock %}

Let’s run our tests:

$ python manage.py test blogengine/
Creating test database for alias 'default'...
.............................
----------------------------------------------------------------------
Ran 29 tests in 10.456s
OK
Destroying test database for alias 'default'...

And commit our changes:

$ git add .
$ git commit -m 'Now use named routes'

Debugging Django

There are a number of handy ways to debug Django applications. One of the simplest is to use the Python debugger. To use it, just enter the following lines at the point you want to break at:

import pdb
pdb.set_trace()

Now, whenever that line of code is run, you’ll be dropped into an interactive shell that lets you play around to find out what’s going wrong. However, it doesn’t offer autocompletion, so we’ll install ipdb, which is an improved version:

$ pip install ipdb
$ pip freeze > requirements.txt

Now you can use ipdb in much the same way as you would use pdb:

import ipdb
ipdb.set_trace()

Now, ipdb is very useful, but it isn’t much help for profiling your application. For that you need the Django Debug Toolbar. Run the following commands:

$ pip install django-debug-toolbar
$ pip freeze > requirements.txt

Then add the following line to INSTALLED_APPS in your settings file:

    'debug_toolbar',

Then, try running the development server, and you’ll see a toolbar on the right-hand side of the screen that allows you to view some useful data about your page. For instance, you’ll notice a field called SQL - this contains details of the queries carried out when building the page. To actually see the queries carried out, you’ll want to disable caching in your settings file by commenting out all the constants that start with CACHE.

We won’t go into using the toolbar to optimise queries, but using this, you can easily see what queries are being executed on a specific page, how long they take, and the values they return. Sometimes, you may need to optimise a slow query - in this case, Django allows you to drop down to writing raw SQL if necessary.

Note that if you’re running Django in production, you should set DEBUG to False as otherwise it gives rather too much information to potential attackers, and with Django Debug Toolbar installed, that’s even more important.

Please also note that when you disable debug mode, Django no longer handles static files automatically, so you’ll need to run python manage.py collectstatic and commit the staticfiles directory.

Once you’ve disabled debug mode, collected the static files, and re-enables caching, you can commit your changes:

$ git add .
$ git commit -m 'Installed debugging tools'

Optimising static files

We want our blog to get the best SEO results it can, so making it fast is essential. One of the simplest things you can do is to concatenate and minify static assets such as CSS and JavaScript. There are numerous ways to do this, but I generally use Grunt. Let’s set up a Grunt config to concatenate and minify our CSS and JavaScript.

You’ll need to have Node.js installed on your development machine for this. Then, you need to install the Grunt command-line interface:

$ sudo npm install -g grunt-cli

With that done, we need to create a package.json file. You can create one using the command npm init. Here’s mine:

{
  "name": "django_tutorial_blog_ng",
  "version": "1.0.0",
  "description": "Django Tutorial Blog NG =======================",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "https://github.com/matthewbdaly/django_tutorial_blog_ng.git"
  },
  "author": "Matthew Daly <matthew@matthewdaly.co.uk> (http://matthewdaly.co.uk/)",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/matthewbdaly/django_tutorial_blog_ng/issues"
  },
  "homepage": "https://github.com/matthewbdaly/django_tutorial_blog_ng"
}

Feel free to amend it as you see fit.

Next we install Grunt and the required plugins:

$ npm install grunt grunt-contrib-cssmin grunt-contrib-concat grunt-contrib-uglify --save-dev

We now need to create a Gruntfile for our tasks:

module.exports = function (grunt) {
    'use strict';
    grunt.initConfig({
        concat: {
            dist: {
                src: [
                    'blogengine/static/bower_components/bootstrap/dist/css/bootstrap.css',
                    'blogengine/static/bower_components/bootstrap/dist/css/bootstrap-theme.css',
                    'blogengine/static/css/code.css',
                    'blogengine/static/css/main.css',
                ],
                dest: 'blogengine/static/css/style.css'
            }
        },
        uglify: {
            dist: {
                src: [
                    'blogengine/static/bower_components/jquery/jquery.js',
                    'blogengine/static/bower_components/bootstrap/dist/js/bootstrap.js'
                ],
                dest: 'blogengine/static/js/all.min.js'
            }
        },
        cssmin: {
            dist: {
                src: 'blogengine/static/css/style.css',
                dest: 'blogengine/static/css/style.min.css'
            }
        }
    });
    grunt.loadNpmTasks('grunt-contrib-concat');
    grunt.loadNpmTasks('grunt-contrib-uglify');
    grunt.loadNpmTasks('grunt-contrib-cssmin');
    grunt.registerTask('default', ['concat', 'uglify', 'cssmin']);
};

You’ll also need to change the paths in your base HTML file to point to the minified versions:

<!DOCTYPE html>
<!--[if lt IE 7]>      <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>         <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>         <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js"> <!--<![endif]-->
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <title>{% block title %}My Django Blog{% endblock %}</title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link rel="alternate" type="application/rss+xml" title="Blog posts" href="/feeds/posts/" >
        <!-- Place favicon.ico and apple-touch-icon.png in the root directory -->
        {% load staticfiles %}
        <link rel="stylesheet" href="{% static 'css/style.min.css' %}">
    </head>
    <body>
        <!--[if lt IE 7]>
            <p class="browsehappy">You are using an <strong>outdated</strong> browser. Please <a href="http://browsehappy.com/">upgrade your browser</a> to improve your experience.</p>
        <![endif]-->
        <!-- Add your site or application content here -->
        <div id="fb-root"></div>
        <script>(function(d, s, id) {
            var js, fjs = d.getElementsByTagName(s)[0];
            if (d.getElementById(id)) return;
                js = d.createElement(s); js.id = id;
                js.src = "//connect.facebook.net/en_GB/all.js#xfbml=1";
                fjs.parentNode.insertBefore(js, fjs);
            }(document, 'script', 'facebook-jssdk'));</script>
        <div class="navbar navbar-static-top navbar-inverse">
            <div class="container-fluid">
                <div class="navbar-header">
                    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#header-nav">
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                    </button>
                    <a class="navbar-brand" href="{% url 'blogengine:index' %}">My Django Blog</a>
                </div>
                <div class="collapse navbar-collapse" id="header-nav">
                    <ul class="nav navbar-nav">
                        {% load flatpages %}
                        {% get_flatpages as flatpages %}
                        {% for flatpage in flatpages %}
                        <li><a href="{{ flatpage.url }}">{{ flatpage.title }}</a></li>
                        {% endfor %}
                        <li><a href="/feeds/posts/">RSS feed</a></li>
                        <form action="/search" method="GET" class="navbar-form navbar-left">
                            <div class="form-group">
                                <input type="text" name="q" placeholder="Search..." class="form-control"></input>
                            </div>
                            <button type="submit" class="btn btn-default">Search</button>
                        </form>
                    </ul>
                </div>
            </div>
        </div>
        <div class="container">
            {% block header %}
                <div class="page-header">
                    <h1>My Django Blog</h1>
                </div>
            {% endblock %}
            <div class="row">
                {% block content %}{% endblock %}
            </div>
        </div>
        <div class="container footer">
            <div class="row">
                <div class="span12">
                    <p>Copyright &copy; {% now "Y" %}</p>
                </div>
            </div>
        </div>
        <script src="{% static 'js/all.min.js' %}"></script>
        <!-- Google Analytics: change UA-XXXXX-X to be your site's ID. -->
        <script>
            (function(b,o,i,l,e,r){b.GoogleAnalyticsObject=l;b[l]||(b[l]=
            function(){(b[l].q=b[l].q||[]).push(arguments)});b[l].l=+new Date;
            e=o.createElement(i);r=o.getElementsByTagName(i)[0];
            e.src='//www.google-analytics.com/analytics.js';
            r.parentNode.insertBefore(e,r)}(window,document,'script','ga'));
            ga('create','UA-XXXXX-X');ga('send','pageview');
        </script>
    </body>
</html>

Now, run the Grunt task:

$ grunt

And collect the static files:

$ python manage.py collectstatic

You’ll also want to add your node_modules folder to your gitignore:

venv/
*.pyc
db.sqlite3
reports/
htmlcov/
.coverage
node_modules/

Then commit your changes:

$ git add .
$ git commit -m 'Optimised static assets'

Now, our package.json will cause a problem - it will mean that this app is mistakenly identified as a Node.js app. To prevent this, create the .slugignore file:

package.json

Then commit your changes and push them up:

$ git add .slugignore
$ git commit -m 'Added slugignore'
$ fab deploy

If you check, your site should now be loading the minified versions of the static files.

That’s our site done! As usual I’ve tagged the final commit with lesson-8.

Sadly, that’s our final instalment over with! I hope you’ve enjoyed these tutorials, and I look forward to seeing what you create with them.

25th August 2014 5:15 pm

Django Blog Tutorial - the Next Generation - Part 7

Hello once again! In this instalment we’ll cover:

• Caching your content with Memcached to improve your site’s performance
• Refactoring and simplifying our tests
• Implementing additional feeds
• Creating a simple search engine

Don’t forget to activate your virtualenv:

$ source venv/bin/activate

Now let’s get started!

Memcached

If you frequent (or used to frequent) social media sites like Reddit, Slashdot or Digg, you may be familiar with something called variously the Digg or Slashdot effect, whereby if a page gets submitted to a social media site, and subsequently becomes popular, it can be hit by a huge number of HTTP requests in a very short period of time, slowing it down or even taking the server down completely.

Now, as a general rule of thumb, for most dynamic websites such as blogs, the bottleneck is not the web server or the programming language, but the database. If you have a lot of people hitting the same page over and over again in quick succession, then you’re essentially running the same query over and over again and getting the same result each time, which is expensive in terms of processing power. What you need to be able to do is cache the results of the query in memory for a given period of time so that the number of queries is reduced.

That’s where Memcached comes in. It’s a simple key-value store that allows you to store values in memory for a given period of time so that they can be retrieved without having to query the database. Memcached is a very common choice for caching, and is by far the fastest and most efficient type of cache available for Django. It’s also available on Heroku’s free tier.

Django has a very powerful caching framework that supports numerous types of cache in addition to Memcached, such as:

• Database caching
• Filesystem caching
• Local memory caching

There are also third-party backends for using other caching systems such as Redis.

Now, the cache can be used in a number of different ways. You can cache only certain parts of your site if you wish. However, because our site is heavily content-driven, we should be pretty safe to use the per-site cache, which is the simplest way to set up caching.

In order to set up Memcached, there’s a couple of Python libraries we’ll need. If you want to install them locally, however, you’ll need to install both memcached and libmemcached (on Ubuntu, the packages you need are called memcached and libmemcached-dev) on your development machine. If you don’t want to do this, then just copy and paste these lines into requirements.txt instead:

django-pylibmc-sasl==0.2.4
pylibmc==1.3.0

If you are happy to install these dependencies locally, then run this command once memcached and libmemcached are installed:

$ pip install pylibmc django-pylibmc-sasl

With that done let’s configure Memcached. Open up the settings file and add the following at the bottom:

def get_cache():
  import os
  try:
    os.environ['MEMCACHE_SERVERS'] = os.environ['MEMCACHIER_SERVERS'].replace(',', ';')
    os.environ['MEMCACHE_USERNAME'] = os.environ['MEMCACHIER_USERNAME']
    os.environ['MEMCACHE_PASSWORD'] = os.environ['MEMCACHIER_PASSWORD']
    return {
      'default': {
        'BACKEND': 'django_pylibmc.memcached.PyLibMCCache',
        'TIMEOUT': 300,
        'BINARY': True,
        'OPTIONS': { 'tcp_nodelay': True }
      }
    }
  except:
    return {
      'default': {
        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache'
      }
    }
CACHES = get_cache()
CACHE_MIDDLEWARE_ALIAS = 'default'
CACHE_MIDDLEWARE_SECONDS = 300
CACHE_MIDDLEWARE_KEY_PREFIX = ''

Then add the following to MIDDLEWARE_CLASSES:

    'django.middleware.cache.UpdateCacheMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.cache.FetchFromCacheMiddleware',

That’s it! The first section configures the application to use Memcached to cache the content when running on Heroku, and sets some configuration parameters, while the second section tells Django to use the per-site cache in order to cache all the site content.

Now, Heroku doesn’t include Memcached by default - instead it’s available as an add-on called Memcachier. To use add-ons you need to set up a credit card for billing. We will set it up to use the free developer plan, but if you outgrow this you can easily switch to a paid plan. To add Memcachier, run this command:

$ heroku addons:add memcachier:dev

Please note that Memcachier can take a few minutes to get set up, so you may want to leave it a little while between adding it and pushing up your changes. Now we’ll commit our changes:

$ git add requirements.txt django_tutorial_blog_ng/settings.py
$ git commit -m 'Implemented caching with Memcached'

Then we’ll push them up to our remote repository and to Heroku:

$ git push origin master
$ git push heroku master

And that’s all you need to do to set up Memcached. In addition to storing your query results in Memcached, enabling the caching framework in Django will also set various HTTP headers to enable web proxies and browsers to cache content for an appropriate length of time. If you open up your browser’s developer tools and compare the response headers for your homepage on the latest version of the code with the previous version, you’ll notice that a number of additional headers appear, including Cache-Control, Expires and Last-Modified. These tell web browsers and web proxies how often to request the latest version of the HTML document, in order to help you reduce the bandwidth used.

As you can see, for a site like this where you are the only person adding content, it’s really easy to implement caching with Django, and for a blog there’s very little reason not to do it. If you’re not using Heroku and are instead hosting your site on a VPS, then the configuration will be somewhat different - see here for details. You can also find information on using other cache backends on the same page.

That isn’t all you can do to speed up your site. Heroku doesn’t seem to be very good for serving static files, and if your site is attracting a lot of traffic you might want to host your static files elsewhere, such as on Amazon’s S3 service. Doing so is outside the scope of this tutorial, but for that use case, you should check out django-storages.

Clearing the cache automatically

There is one issue with this implementation. As it is right now, if you view the home page, add a post, then reload the page, you may not see the new post immediately because the cache will continue serving the old version until it has expired. That behaviour is less than ideal - we would like the cache to be cleared automatically when a new post gets added so that users will see the new version immediately. That response will still be cached afterwards, so it only means one extra query.

This is the ideal place to introduce signals. Signals are a way to carry out a given action when an event takes place. In our case, we plan to clear the cache when a post is saved (either created or updated).

Note that as we’ll be testing the behaviour of the cache at this point, you’ll need to install Memcached on your local machine, and we’ll need to change the settings to fall back to our local Memcached instance:

def get_cache():
  import os
  try:
    os.environ['MEMCACHE_SERVERS'] = os.environ['MEMCACHIER_SERVERS'].replace(',', ';')
    os.environ['MEMCACHE_USERNAME'] = os.environ['MEMCACHIER_USERNAME']
    os.environ['MEMCACHE_PASSWORD'] = os.environ['MEMCACHIER_PASSWORD']
    return {
      'default': {
        'BACKEND': 'django_pylibmc.memcached.PyLibMCCache',
        'TIMEOUT': 300,
        'BINARY': True,
        'OPTIONS': { 'tcp_nodelay': True }
      }
    }
  except:
    return {
      'default': {
        'BACKEND': 'django.core.cache.backends.memcached.PyLibMCCache',
        'LOCATION': '127.0.0.1:11211'
      }
    }
CACHES = get_cache()
CACHE_MIDDLEWARE_ALIAS = 'default'
CACHE_MIDDLEWARE_SECONDS = 300
CACHE_MIDDLEWARE_KEY_PREFIX = ''

If you don’t want to install Memcached locally, you can skip this step, but be aware that the test we write for clearing the cache will always pass if you do skip it.

Then we’ll run our tests to make sure nothing has been broken:

$ python manage.py jenkins blogengine
Creating test database for alias 'default'...
.......................
----------------------------------------------------------------------
Ran 23 tests in 6.164s
OK

Let’s commit:

$ git add django_tutorial_blog_ng/settings.py
$ git commit -m 'Now use Memcached in development'

Now we’ll add a test for clearing the cache to PostViewTest:

    def test_clear_cache(self):
        # Create the category
        category = Category()
        category.name = 'python'
        category.description = 'The Python programming language'
        category.save()
        # Create the tag
        tag = Tag()
        tag.name = 'perl'
        tag.description = 'The Perl programming language'
        tag.save()
        # Create the author
        author = User.objects.create_user('testuser', 'user@example.com', 'password')
        author.save()
        # Create the site
        site = Site()
        site.name = 'example.com'
        site.domain = 'example.com'
        site.save()
        # Create the first post
        post = Post()
        post.title = 'My first post'
        post.text = 'This is [my first blog post](http://127.0.0.1:8000/)'
        post.slug = 'my-first-post'
        post.pub_date = timezone.now()
        post.author = author
        post.site = site
        post.category = category
        post.save()
        post.tags.add(tag)
        # Check new post saved
        all_posts = Post.objects.all()
        self.assertEquals(len(all_posts), 1)
        # Fetch the index
        response = self.client.get('/')
        self.assertEquals(response.status_code, 200)
        # Create the second post
        post = Post()
        post.title = 'My second post'
        post.text = 'This is [my second blog post](http://127.0.0.1:8000/)'
        post.slug = 'my-second-post'
        post.pub_date = timezone.now()
        post.author = author
        post.site = site
        post.category = category
        post.save()
        post.tags.add(tag)
        # Fetch the index again
        response = self.client.get('/')
        # Check second post present
        self.assertTrue('my second blog post' in response.content)

This should be fairly self-explanatory. We create one post, and request the index page. We then add a second post, request the index page again, and check for the second post. The test should fail because the cached version is returned, rather than the version in the database.

Now we have a test in place, we can implement a fix. First, add this to the top of your models.py:

from django.db.models.signals import post_save
from django.core.cache import cache

Then add the following at the bottom of the file:

# Define signals
def new_post(sender, instance, created, **kwargs):
    cache.clear()
# Set up signals
post_save.connect(new_post, sender=Post)

This is fairly straightforward. What we’re doing is first defining a function called new_post that is called when a new post is created. We then connect it to the post_save signal. When a post is saved, it calls new_post, which clears the cache, making sure users are seeing the latest and greatest version of your site immediately.

Let’s test it:

$ python manage.py jenkins blogengine
Creating test database for alias 'default'...
........................
----------------------------------------------------------------------
Ran 24 tests in 8.473s
OK
Destroying test database for alias 'default'...

There are a number of signals available, and when you create one, you have access to the created object via the instance parameter. Using signals you can implement all kinds of functionality. For instance, you could implement the functionality to send an email when a new post is published.

If you’re using Travis CI, you’ll also need to update the config file:

language: python
python:
- "2.7"
services: memcached
before_install:
    - sudo apt-get install -y libmemcached-dev
# command to install dependencies
install: "pip install -r requirements.txt"
# command to run tests
script: coverage run --include="blogengine/*" --omit="blogengine/migrations/*" manage.py test blogengine
after_success:
    coveralls

Time to commit:

$ git add blogengine/ .travis.yml
$ git commit -m 'Now clear cache when post added'

Formatting for RSS feeds

Now, we want to offer more than one option for RSS feeds. For instance, if your blog is aggregated on a site such as Planet Python, but you also blog about JavaScript, you may want to be able to provide a feed for posts in the python category only.

If you have written any posts that use any of Markdown’s custom formatting, you may notice that if you load your RSS feed in a reader, it isn’t formatted as Markdown. Let’s fix that. First we’ll amend our test:

class FeedTest(BaseAcceptanceTest):
    def test_all_post_feed(self):
        # Create the category
        category = Category()
        category.name = 'python'
        category.description = 'The Python programming language'
        category.save()
        # Create the tag
        tag = Tag()
        tag.name = 'python'
        tag.description = 'The Python programming language'
        tag.save()
        # Create the author
        author = User.objects.create_user('testuser', 'user@example.com', 'password')
        author.save()
        # Create the site
        site = Site()
        site.name = 'example.com'
        site.domain = 'example.com'
        site.save()
        # Create a post
        post = Post()
        post.title = 'My first post'
        post.text = 'This is my *first* blog post'
        post.slug = 'my-first-post'
        post.pub_date = timezone.now()
        post.author = author
        post.site = site
        post.category = category
        # Save it
        post.save()
        # Add the tag
        post.tags.add(tag)
        post.save()
        # Check we can find it
        all_posts = Post.objects.all()
        self.assertEquals(len(all_posts), 1)
        only_post = all_posts[0]
        self.assertEquals(only_post, post)
        # Fetch the feed
        response = self.client.get('/feeds/posts/')
        self.assertEquals(response.status_code, 200)
        # Parse the feed
        feed = feedparser.parse(response.content)
        # Check length
        self.assertEquals(len(feed.entries), 1)
        # Check post retrieved is the correct one
        feed_post = feed.entries[0]
        self.assertEquals(feed_post.title, post.title)
        self.assertTrue('This is my <em>first</em> blog post' in feed_post.description)

Don’t forget to run the tests to make sure they fail. Now, let’s fix it:

from django.shortcuts import render
from django.views.generic import ListView
from blogengine.models import Category, Post, Tag
from django.contrib.syndication.views import Feed
from django.utils.encoding import force_unicode
from django.utils.safestring import mark_safe
import markdown2
# Create your views here.
class CategoryListView(ListView):
    def get_queryset(self):
        slug = self.kwargs['slug']
        try:
            category = Category.objects.get(slug=slug)
            return Post.objects.filter(category=category)
        except Category.DoesNotExist:
            return Post.objects.none()
class TagListView(ListView):
    def get_queryset(self):
        slug = self.kwargs['slug']
        try:
            tag = Tag.objects.get(slug=slug)
            return tag.post_set.all()
        except Tag.DoesNotExist:
            return Post.objects.none()
class PostsFeed(Feed):
    title = "RSS feed - posts"
    link = "feeds/posts/"
    description = "RSS feed - blog posts"
    def items(self):
        return Post.objects.order_by('-pub_date')
    def item_title(self, item):
        return item.title
    def item_description(self, item):
        extras = ["fenced-code-blocks"]
        content = mark_safe(markdown2.markdown(force_unicode(item.text),
                                               extras = extras))
        return content

All we’re doing here is amending the item_description method of PostsFeed to render it as Markdown. Now let’s run our tests again:

$ python manage.py jenkins
Creating test database for alias 'default'...
........................
----------------------------------------------------------------------
Ran 24 tests in 9.370s
OK
Destroying test database for alias 'default'...

With that done, we’ll commit our changes:

$ git add blogengine/
$ git commit -m 'Fixed rendering for post feed'

Refactoring our tests

Now, before we get into implementing the feed, our tests are a bit verbose. We create a lot of items over and over again - let’s sort that out. Factory Boy is a handy Python module that allows you to create easy-to-use factories for creating objects over and over again in tests. Let’s install it:

$ pip install factory_boy
$ pip freeze > requirements.txt
$ git add requirements.txt
$ git commit -m 'Installed Factory Boy'

Now let’s set up a factory for creating posts. Add this at the top of the test file:

import factory.django

Then, before your actual tests, insert the following:

# Factories
class SiteFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Site
        django_get_or_create = (
            'name',
            'domain'
        )
    name = 'example.com'
    domain = 'example.com'

Now, wherever you call Site(), add its attributes, and save it, replace those lines with the following:

        site = SiteFactory()

Much simpler and more concise, I’m sure you’ll agree! Now, let’s run the tests to make sure they aren’t broken:

$ python manage.py test blogengine
Creating test database for alias 'default'...
........................
----------------------------------------------------------------------
Ran 24 tests in 7.482s
OK
Destroying test database for alias 'default'...

Let’s commit again:

$ git add blogengine/tests.py
$ git commit -m 'Now use Factory Boy for site objects'

Let’s do the same thing with Category objects:

class CategoryFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Category
        django_get_or_create = (
            'name',
            'description',
            'slug'
        )
    name = 'python'
    description = 'The Python programming language'
    slug = 'python'

Again, just find every time we call Category() and replace it with the following:

        category = CategoryFactory()

Now if we run our tests, we’ll notice a serious error:

$ python manage.py test blogengine
Creating test database for alias 'default'...
EE..EE.EE.EE...E.EEE..E.
======================================================================
ERROR: test_create_category (blogengine.tests.PostTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 42, in test_create_category
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_create_post (blogengine.tests.PostTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 80, in test_create_post
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_create_post (blogengine.tests.AdminTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 339, in test_create_post
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_create_post_without_tag (blogengine.tests.AdminTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 378, in test_create_post_without_tag
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_delete_category (blogengine.tests.AdminTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 245, in test_delete_category
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_delete_post (blogengine.tests.AdminTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 467, in test_delete_post
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_edit_category (blogengine.tests.AdminTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 221, in test_edit_category
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_edit_post (blogengine.tests.AdminTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 410, in test_edit_post
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_all_post_feed (blogengine.tests.FeedTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 810, in test_all_post_feed
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_category_page (blogengine.tests.PostViewTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 640, in test_category_page
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_clear_cache (blogengine.tests.PostViewTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 753, in test_clear_cache
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_index (blogengine.tests.PostViewTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 518, in test_index
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
======================================================================
ERROR: test_post_page (blogengine.tests.PostViewTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 576, in test_post_page
    category = CategoryFactory()
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 82, in __call__
    return cls.create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 585, in create
    return cls._generate(True, attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 510, in _generate
    obj = cls._prepare(create, **attrs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/base.py", line 485, in _prepare
    return cls._create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 151, in _create
    return cls._get_or_create(model_class, *args, **kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/factory/django.py", line 142, in _get_or_create
    obj, _created = manager.get_or_create(*args, **key_fields)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 154, in get_or_create
    return self.get_queryset().get_or_create(**kwargs)
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/venv/lib/python2.7/site-packages/django/db/models/query.py", line 383, in get_or_create
    obj.save(force_insert=True, using=self.db)
TypeError: save() got an unexpected keyword argument 'force_insert'
----------------------------------------------------------------------
Ran 24 tests in 5.162s
FAILED (errors=13)
Destroying test database for alias 'default'...

Thankfully, this is easy to fix. We just need to amend the custom save() method of the Category model:

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(unicode(self.name))
        super(Category, self).save(*args, **kwargs)

That should resolve the issue:

$ python manage.py jenkins
Creating test database for alias 'default'...
........................
----------------------------------------------------------------------
Ran 24 tests in 7.749s
OK
Destroying test database for alias 'default'...

Let’s commit again:

$ git add blogengine/
$ git commit -m 'Category now uses Factory Boy'

Now let’s do the same thing for tags:

class TagFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Tag
        django_get_or_create = (
            'name',
            'description',
            'slug'
        )
    name = 'python'
    description = 'The Python programming language'
    slug = 'python'

And replace the sections where we create new Tag objects:

        tag = TagFactory()

Note that some tags have different values. We can easily pass different values to our TagFactory() to override the default values:

        tag = TagFactory(name='perl', description='The Perl programming language')

The Tag model has the same issue as the Category one did, so let’s fix that:

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(unicode(self.name))
        super(Tag, self).save(*args, **kwargs)

We run our tests again:

$ python manage.py test blogengine/
Creating test database for alias 'default'...
........................
----------------------------------------------------------------------
Ran 24 tests in 7.153s
OK
Destroying test database for alias 'default'...

Time to commit again:

$ git add blogengine/
$ git commit -m 'Now use Factory Boy for tags'

Next we’ll create a factory for adding users. Note that the factory name doesn’t have to match the object name, so you can create factories for different types of users. Here we create a factory for authors - you could, for instance, create a separate factory for subscribers if you wanted:

class AuthorFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = User
        django_get_or_create = ('username','email', 'password',)
    username = 'testuser'
    email = 'user@example.com'
    password = 'password'

And as before, replace those sections where we create users with the following:

        author = AuthorFactory()

Run the tests again:

$ python manage.py test blogengine
Creating test database for alias 'default'...
........................
----------------------------------------------------------------------
Ran 24 tests in 5.808s
OK
Destroying test database for alias 'default'...

We commit our changes:

$ git add blogengine/
$ git commit -m 'Now use Factory Boy for creating authors'

Now we’ll create a flat page factory:

class FlatPageFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = FlatPage
        django_get_or_create = (
            'url',
            'title',
            'content'
        )
    url = '/about/'
    title = 'About me'
    content = 'All about me'

And use it for our flat page test:

        page = FlatPageFactory()

Check the tests pass:

$ python manage.py test blogengine
Creating test database for alias 'default'...
........................
----------------------------------------------------------------------
Ran 24 tests in 5.796s
OK
Destroying test database for alias 'default'...

And commit again:

$ git add blogengine/
$ git commit -m 'Now use Factory Boy for flat page test'

Now we’ll create a final factory for posts:

class PostFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Post
        django_get_or_create = (
            'title',
            'text',
            'slug',
            'pub_date'
        )
    title = 'My first post'
    text = 'This is my first blog post'
    slug = 'my-first-post'
    pub_date = timezone.now()
    author = factory.SubFactory(AuthorFactory)
    site = factory.SubFactory(SiteFactory)
    category = factory.SubFactory(CategoryFactory)

This factory is a little bit different. Because our Post model depends on several others, we need to be able to create those additional objects on demand. By designating them as subfactories, we can easily create the associated objects for our Post object.

That means that not only can we get rid of our Post() calls, but we can also get rid of the factory calls to create the associated objects for Post models. Again, I’ll leave actually doing this as an exercise for the reader, but you can always refer to the GitHub repository if you’re not too sure.

Make sure your tests still pass, then commit the changes:

$ git add blogengine/
$ git commit -m 'Now use Factory Boy for testing posts'

Using Factory Boy made a big difference to the size of the test file - I was able to cut it down by over 200 lines of code. As your application gets bigger, it gets harder to maintain, so do what you can to keep the size down.

Additional RSS feeds

Now, let’s implement our additional RSS feeds. First, we’ll write a test for the category feed. Add this to the FeedTest class:

    def test_category_feed(self):
        # Create a post
        post = PostFactory(text='This is my *first* blog post')
        # Create another post in a different category
        category = CategoryFactory(name='perl', description='The Perl programming language', slug='perl')
        post2 = PostFactory(text='This is my *second* blog post', title='My second post', slug='my-second-post', category=category)
        # Fetch the feed
        response = self.client.get('/feeds/posts/category/python/')
        self.assertEquals(response.status_code, 200)
        # Parse the feed
        feed = feedparser.parse(response.content)
        # Check length
        self.assertEquals(len(feed.entries), 1)
        # Check post retrieved is the correct one
        feed_post = feed.entries[0]
        self.assertEquals(feed_post.title, post.title)
        self.assertTrue('This is my <em>first</em> blog post' in feed_post.description)
        # Check other post is not in this feed
        self.assertTrue('This is my <em>second</em> blog post' not in response.content)

Here we create two posts in different categories (note that we create a new category and override the post category for it). We then fetch /feeds/posts/category/python/ and assert that it contains only one post, with the content of the first post and not the content of the second.

Run the tests and they should fail:

$ python manage.py test blogengine
Creating test database for alias 'default'...
................F........
======================================================================
FAIL: test_category_feed (blogengine.tests.FeedTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/matthewdaly/Projects/django_tutorial_blog_ng/blogengine/tests.py", line 716, in test_category_feed
    self.assertEquals(response.status_code, 200)
AssertionError: 404 != 200
----------------------------------------------------------------------
Ran 25 tests in 5.804s
FAILED (failures=1)
Destroying test database for alias 'default'...

Because we haven’t yet implemented that route, we get a 404 error. So let’s create a route for this:

from django.conf.urls import patterns, url
from django.views.generic import ListView, DetailView
from blogengine.models import Post, Category, Tag
from blogengine.views import CategoryListView, TagListView, PostsFeed, CategoryPostsFeed
urlpatterns = patterns('',
    # Index
    url(r'^(?P<page>\d+)?/?$', ListView.as_view(
        model=Post,
        paginate_by=5,
        )),
    # Individual posts
    url(r'^(?P<pub_date__year>\d{4})/(?P<pub_date__month>\d{1,2})/(?P<slug>[a-zA-Z0-9-]+)/?$', DetailView.as_view(
        model=Post,
        )),
    # Categories
    url(r'^category/(?P<slug>[a-zA-Z0-9-]+)/?$', CategoryListView.as_view(
        paginate_by=5,
        model=Category,
        )),
    # Tags
    url(r'^tag/(?P<slug>[a-zA-Z0-9-]+)/?$', TagListView.as_view(
        paginate_by=5,
        model=Tag,
        )),
    # Post RSS feed
    url(r'^feeds/posts/$', PostsFeed()),
    # Category RSS feed
    url(r'^feeds/posts/category/(?P<slug>[a-zA-Z0-9-]+)/?$', CategoryPostsFeed()),
)

Note that the category RSS feed route is similar to the post RSS feed route, but accepts a slug parameter. We will use this to pass through the slug for the category in question. Also note we import the CategoryPostsFeed view. Now, we need to create that view. Fortunately, because it’s written as a Python class, we can extend the existing PostsFeed class. Open up your views file and amend it to look like this:

from django.shortcuts import get_object_or_404
from django.views.generic import ListView
from blogengine.models import Category, Post, Tag
from django.contrib.syndication.views import Feed
from django.utils.encoding import force_unicode
from django.utils.safestring import mark_safe
import markdown2
# Create your views here.
class CategoryListView(ListView):
    def get_queryset(self):
        slug = self.kwargs['slug']
        try:
            category = Category.objects.get(slug=slug)
            return Post.objects.filter(category=category)
        except Category.DoesNotExist:
            return Post.objects.none()
class TagListView(ListView):
    def get_queryset(self):
        slug = self.kwargs['slug']
        try:
            tag = Tag.objects.get(slug=slug)
            return tag.post_set.all()
        except Tag.DoesNotExist:
            return Post.objects.none()
class PostsFeed(Feed):
    title = "RSS feed - posts"
    description = "RSS feed - blog posts"
    link = '/'
    def items(self):
        return Post.objects.order_by('-pub_date')
    def item_title(self, item):
        return item.title
    def item_description(self, item):
        extras = ["fenced-code-blocks"]
        content = mark_safe(markdown2.markdown(force_unicode(item.text),
                                               extras = extras))
        return content
class CategoryPostsFeed(PostsFeed):
    def get_object(self, request, slug):
        return get_object_or_404(Category, slug=slug)
    def title(self, obj):
        return "RSS feed - blog posts in category %s" % obj.name
    def link(self, obj):
        return obj.get_absolute_url()
    def description(self, obj):
        return "RSS feed - blog posts in category %s" % obj.name
    def items(self, obj):
        return Post.objects.filter(category=obj).order_by('-pub_date')

Note that many of our fields don’t have to be explicitly defined as they are inherited from PostsFeed. We can’t hard-code the title, link or description because they depend on the category, so we instead define methods to return the appropriate text.

Also note get_object() - we define this so that we can ensure the category exists. If it doesn’t exist, then it returns a 404 error rather than showing an empty feed.

We also override items() to filter it to just those posts that are in the given category.

If you run the tests again, they should now pass:

$ python manage.py test blogengine
Creating test database for alias 'default'...
.........................
----------------------------------------------------------------------
Ran 25 tests in 5.867s
OK
Destroying test database for alias 'default'...

Let’s commit our changes:

$ git add blogengine/
$ git commit -m 'Implemented category RSS feed'

Now, we can get our category RSS feed, but how do we navigate to it? Let’s add a link to each category page that directs a user to its RSS feed. To do so, we’ll need to create a new template for category pages. First, let’s add some code to our tests to ensure that the right template is used at all times. Add the following to the end of the test_index method of PostViewTest:

        # Check the correct template was used
        self.assertTemplateUsed(response, 'blogengine/post_list.html')

Then, add this to the end of test_post_page:

        # Check the correct template was used
        self.assertTemplateUsed(response, 'blogengine/post_detail.html')

Finally, add this to the end of test_category_page:

        # Check the correct template was used
        self.assertTemplateUsed(response, 'blogengine/category_post_list.html')

These assertions confirm which template was used to generate which request.

Next, we head into our views file:

class CategoryListView(ListView):
    template_name = 'blogengine/category_post_list.html'
    def get_queryset(self):
        slug = self.kwargs['slug']
        try:
            category = Category.objects.get(slug=slug)
            return Post.objects.filter(category=category)
        except Category.DoesNotExist:
            return Post.objects.none()
    def get_context_data(self, **kwargs):
        context = super(CategoryListView, self).get_context_data(**kwargs)
        slug = self.kwargs['slug']
        try:
            context['category'] = Category.objects.get(slug=slug)
        except Category.DoesNotExist:
            context['category'] = None
        return context

Note that we first of all change the template used by this view. Then, we override get_context_data to add in additional data. What we’re doing is getting the slug that was passed through, looking up any category for which it is the slug, and returning it as additional context data. Using this method, you can easily add additional data that you may wish to render in your Django templates.

Finally, we create our new template:

{% extends "blogengine/includes/base.html" %}
    {% load custom_markdown %}
    {% block content %}
        {% if object_list %}
            {% for post in object_list %}
            <div class="post col-md-12">
            <h1><a href="{{ post.get_absolute_url }}">{{ post.title }}</a></h1>
            <h3>{{ post.pub_date }}</h3>
            {{ post.text|custom_markdown }}
            </div>
            {% if post.category %}
            <div class="col-md-12">
            <a href="{{ post.category.get_absolute_url }}"><span class="label label-primary">{{ post.category.name }}</span></a>
            </div>
            {% endif %}
            {% if post.tags %}
            <div class="col-md-12">
            {% for tag in post.tags.all %}
            <a href="{{ tag.get_absolute_url }}"><span class="label label-success">{{ tag.name }}</span></a>
            {% endfor %}
            </div>
            {% endif %}
            {% endfor %}
        {% else %}
            <p>No posts found</p>
        {% endif %}
        <ul class="pager">
        {% if page_obj.has_previous %}
        <li class="previous"><a href="/{{ page_obj.previous_page_number }}/">Previous Page</a></li>
        {% endif %}
        {% if page_obj.has_next %}
        <li class="next"><a href="/{{ page_obj.next_page_number }}/">Next Page</a></li>
        {% endif %}
        </ul>
        <a href="/feeds/posts/category/{{ category.slug }}/">RSS feed for category {{ category.name }}</a>
    {% endblock %}

Note that the category has been passed through to the template and is now accessible. If you run the tests, they should now pass:

$ python manage.py jenkins
Creating test database for alias 'default'...
.........................
----------------------------------------------------------------------
Ran 25 tests in 7.232s
OK
Destroying test database for alias 'default'...

With that done. we can commit our changes:

$ git add templates/ blogengine/
$ git commit -m 'Added link to RSS feed from category page'

Next up, let’s implement another RSS feed for tags. First, we’ll implement our test:

      def test_tag_feed(self):
          # Create a post
          post = PostFactory(text='This is my *first* blog post')
          tag = TagFactory()
          post.tags.add(tag)
          post.save()
          # Create another post with a different tag
          tag2 = TagFactory(name='perl', description='The Perl programming language', slug='perl')
          post2 = PostFactory(text='This is my *second* blog post', title='My second post', slug='my-second-post')
          post2.tags.add(tag2)
          post2.save()
          # Fetch the feed
          response = self.client.get('/feeds/posts/tag/python/')
          self.assertEquals(response.status_code, 200)
          # Parse the feed
          feed = feedparser.parse(response.content)
          # Check length
          self.assertEquals(len(feed.entries), 1)
          # Check post retrieved is the correct one
          feed_post = feed.entries[0]
          self.assertEquals(feed_post.title, post.title)
          self.assertTrue('This is my <em>first</em> blog post' in feed_post.description)
          # Check other post is not in this feed
          self.assertTrue('This is my <em>second</em> blog post' not in response.content)