Now we only have Post model, what about receiving some feedback from your readers?

Let's open blog/models.py and append this piece of code to the end of file:

class Comment(models.Model):
    post = models.ForeignKey('blog.Post', related_name='comments')
    author = models.CharField(max_length=200)
    text = models.TextField()
    created_date = models.DateTimeField(default=timezone.now)
    approved_comment = models.BooleanField(default=False)

    def approve(self):
        self.approved_comment = True
        self.save()

    def __str__(self):
        return self.text

You can go back to Django models chapter in tutorial if you need to remind yourself what each of field types means.

In this chapter we have new type of field:

• models.BooleanField - this is true/false field.

And related_name option in models.ForeignKey allow us to have access to comments from post model.

Now it's time to add our comment model to database. To do this we have to let know Django that we made changes in our model. Type python manage.py makemigrations blog. Just like this:

(myvenv) ~/djangogirls$ python manage.py makemigrations blog
Migrations for 'blog':
  0002_comment.py:
    - Create model Comment

You can see that this command created for us another migration file in blog/migrations/ directory. Now we need to apply those changes with python manage.py migrate blog. It should look like this:

(myvenv) ~/djangogirls$ python manage.py migrate blog
Operations to perform:
  Apply all migrations: blog
Running migrations:
  Rendering model states... DONE
  Applying blog.0002_comment... OK

Our Comment model exists in database now. It would be nice if we had access to it in our admin panel.

To register model in admin panel, go to blog/admin.py and add line:

admin.site.register(Comment)

Don't forget to import Comment model, file should look like this:

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

admin.site.register(Post)
admin.site.register(Comment)

If you type python manage.py runserver in command prompt and go to http://127.0.0.1:8000/admin/ in your browser, you should have access to list, add and remove comments. Don't hesitate to play with it!

Go to blog/templates/blog/post_detail.html file and add those lines before {% endblock %} tag:

<hr>
{% for comment in post.comments.all %}
    <div class="comment">
        <div class="date">{{ comment.created_date }}</div>
        <strong>{{ comment.author }}</strong>
        <p>{{ comment.text|linebreaks }}</p>
    </div>
{% empty %}
    <p>No comments here yet :(</p>
{% endfor %}

Now we can see the comments section on pages with post details.

But it can look a little bit better, add some css to static/css/blog.css:

.comment {
    margin: 20px 0px 20px 20px;
}

We can also let visitors know about comments on the post list page. Go to the blog/templates/blog/post_list.html file and add line:

<a href="{% url 'blog.views.post_detail' pk=post.pk %}">Comments: {{ post.comments.count }}</a>

After that our template should look like this:

{% extends 'blog/base.html' %}

{% block content %}
    {% for post in posts %}
        <div class="post">
            <div class="date">
                {{ post.published_date }}
            </div>
            <h1><a href="{% url 'blog.views.post_detail' pk=post.pk %}">{{ post.title }}</a></h1>
            <p>{{ post.text|linebreaks }}</p>
            <a href="{% url 'blog.views.post_detail' pk=post.pk %}">Comments: {{ post.comments.count }}</a>
        </div>
    {% endfor %}
{% endblock content %}

Right now we can see comments on our blog, but we cannot add them, let's change that!

Go to blog/forms.py and add those lines to the end of the file:

class CommentForm(forms.ModelForm):

    class Meta:
        model = Comment
        fields = ('author', 'text',)

Don't forget to import Comment model, change line:

from .models import Post

into:

from .models import Post, Comment

Now go to blog/templates/blog/post_detail.html and before line {% for comment in post.comments.all %} add:

<a class="btn btn-default" href="{% url 'add_comment_to_post' pk=post.pk %}">Add comment</a>

Go to post detail page and you should see error:

Let's fix this! Go to blog/urls.py and add this pattern to urlpatterns:

url(r'^post/(?P<pk>\d+)/comment/$', views.add_comment_to_post, name='add_comment_to_post'),

Now you should see this error:

To fix this, add this piece of code to blog/views.py:

def add_comment_to_post(request, pk):
    post = get_object_or_404(Post, pk=pk)
    if request.method == "POST":
        form = CommentForm(request.POST)
        if form.is_valid():
            comment = form.save(commit=False)
            comment.post = post
            comment.save()
            return redirect('blog.views.post_detail', pk=post.pk)
    else:
        form = CommentForm()
    return render(request, 'blog/add_comment_to_post.html', {'form': form})

Don't forget about imports at the beginning of the file:

from .forms import PostForm, CommentForm

Now, on the post detail page, you should see the "Add Comment" button

However, when you click that button, you should see:

Like error mentions, template does not exist, create one as blog/templates/blog/add_comment_to_post.html and add those lines:

{% extends 'blog/base.html' %}

{% block content %}
    <h1>New comment</h1>
    <form method="POST" class="post-form">{% csrf_token %}
        {{ form.as_p }}
        <button type="submit" class="save btn btn-default">Send</button>
    </form>
{% endblock %}

Yay! Now your readers can let you know what they think below your posts!

Not all of our comments should be displayed. Blog owner should have option to approve or delete comments. Let's do something about it.

Go to blog/templates/blog/post_detail.html and change lines:

{% for comment in post.comments.all %}
    <div class="comment">
        <div class="date">{{ comment.created_date }}</div>
        <strong>{{ comment.author }}</strong>
        <p>{{ comment.text|linebreaks }}</p>
    </div>
{% empty %}
    <p>No comments here yet :(</p>
{% endfor %}

to:

{% for comment in post.comments.all %}
    {% if user.is_authenticated or comment.approved_comment %}
    <div class="comment">
        <div class="date">
            {{ comment.created_date }}
            {% if not comment.approved_comment %}
                <a class="btn btn-default" href="{% url 'comment_remove' pk=comment.pk %}"><span class="glyphicon glyphicon-remove"></span></a>
                <a class="btn btn-default" href="{% url 'comment_approve' pk=comment.pk %}"><span class="glyphicon glyphicon-ok"></span></a>
            {% endif %}
        </div>
        <strong>{{ comment.author }}</strong>
        <p>{{ comment.text|linebreaks }}</p>
    </div>
    {% endif %}
{% empty %}
    <p>No comments here yet :(</p>
{% endfor %}

You should see NoReverseMatch, because no url matches comment_remove and comment_approve patterns.

Add url patterns to blog/urls.py:

url(r'^comment/(?P<pk>\d+)/approve/$', views.comment_approve, name='comment_approve'),
url(r'^comment/(?P<pk>\d+)/remove/$', views.comment_remove, name='comment_remove'),

Now you should see AttributeError. To get rid of it, create more views in blog/views.py:

@login_required
def comment_approve(request, pk):
    comment = get_object_or_404(Comment, pk=pk)
    comment.approve()
    return redirect('blog.views.post_detail', pk=comment.post.pk)

@login_required
def comment_remove(request, pk):
    comment = get_object_or_404(Comment, pk=pk)
    post_pk = comment.post.pk
    comment.delete()
    return redirect('blog.views.post_detail', pk=post_pk)

And of course fix imports.

Everything works, but there is one misconception. In our post list page under posts we see number of all comments attached, but we want to have number of approved comments there.

Go to blog/templates/blog/post_list.html and change line:

<a href="{% url 'blog.views.post_detail' pk=post.pk %}">Comments: {{ post.comments.count }}</a>

to:

<a href="{% url 'blog.views.post_detail' pk=post.pk %}">Comments: {{ post.approved_comments.count }}</a>

And also add this method to Post model in blog/models.py:

def approved_comments(self):
    return self.comments.filter(approved_comment=True)

Now your comment feature is finished! Congrats! :-)