More Views

Blogs should be interactive. Let’s allow visitors to comment on each post.

Adding a Comment model

First we need to add a Comment model in blog/

class Comment(models.Model):
    post = models.ForeignKey(Post)
    name = models.CharField(max_length=100)
    email = models.EmailField()
    body = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True, editable=False)
    modified_at = models.DateTimeField(auto_now=True, editable=False)

Let’s write a __unicode___ method for our Comment model like we did for our Post model earlier.

First we should create a test in blog/ Our test should look very similar to the __unicode__ test we wrote for posts earlier. This should suffice:

class CommentModelTest(TestCase):

    def test_unicode_representation(self):
        comment = Comment(body="My comment body")
        self.assertEqual(unicode(comment), "My comment body")

Don’t forget to import our Comment model:

from .models import Post, Comment

Now let’s run our tests to make sure our new test fails:

$ python test blog
Creating test database for alias 'default'...
FAIL: test_unicode_representation (blog.tests.CommentModelTest)
Traceback (most recent call last):
AssertionError: u'Comment object' != 'My comment body'

Ran 10 tests in 0.077s

FAILED (failures=1)
Destroying test database for alias 'default'...

Great. After we implement our __unicode__ method our tests should pass:

$ python test blog
Creating test database for alias 'default'...
Ran 10 tests in 0.072s

Destroying test database for alias 'default'...

Since we have added a new model, we also need to make sure that this model gets synched to our SQLite database.

$ python syncdb

Adding comments on the admin site

Let’s add the Comment model to the admin just like we did with the Post model. This involves editing blog/ to look like this:

from django.contrib import admin
from .models import Post, Comment

If you start the development server again, you will see the Comment model in the admin and you can add comments to the blog posts. However, the point of a blog is to let other users and not only the admin post comments.

Displaying comments on the website

Now we can create comments in the admin interface, but we can’t see them on the website yet. Let’s display comments on the detail page for each blog post.

At the end of our content block in templates/blog/post_detail.html let’s add the following:

{% for comment in post.comment_set.all %}
    <p><em>Posted by {{ }}</em></p>
    {{ comment|linebreaks }}
{% empty %}
    No comments yet.
{% endfor %}


We forgot to add a test for this! Why don’t you add a test to make sure comments appear on the blog post page.

Now we can see our comments on the website.