A little Hacker News in Django (part 8)

3 min readJun 12, 2018

Let’s start by creating a view to upvote a comment. We can reuse our set_upvoted_post view.

def create_upvote_view(model):
    @require_POST
    @login_required
    def view(request, id):
        obj = get_object_or_404(model, id=id)
        try:
            upvoted = json.loads(request.body.decode('utf-8'))['upvoted']
        except (json.JSONDecodeError, KeyError):
            return HttpResponseBadRequest()
        obj.set_upvoted(request.user, upvoted=upvoted)
        # 204: No content
        return HttpResponse(status=204)
    return view

Now I can do this:

set_upvoted_post = create_upvote_view(Post)
set_upvoted_comment = create_upvote_view(Comment)

Let’s try to upvote here: http://localhost:8000/posts/.

TypeError: view() got an unexpected keyword argument 'post_id'

It doesn’t work very well. Let’s try to change the interface.

@upvote_view
def set_upvoted_post(request, post_id):
    return get_object_or_404(Post, id=post_id)


@upvote_view
def set_upvoted_comment(request, comment_id):
    return get_object_or_404(Comment, id=comment_id)

Yeah, it might look a little bit magic, I wouldn’t necessarily advice you to do the same type of things. But it’s cool, so let’s do it.

def upvote_view(view):
    @wraps(view)
    @require_POST
    @login_required
    def new_view(request, *args, **kwargs):
        obj = view(request, *args, **kwargs)
        try:
            upvoted = json.loads(request.body.decode('utf-8'))['upvoted']
        except (json.JSONDecodeError, KeyError):
            return HttpResponseBadRequest()
        obj.set_upvoted(request.user, upvoted=upvoted)
        # 204: No content
        return HttpResponse(status=204)
    return new_view

Now let’s add set_upvoted_comment to the routes. Now, comes a problem. Right now, everything is in the posts model. The route to set upvoted for a post is /posts/<post_id>/set_upvoted/. Now, if we follow the logic, the route for comments should be /comments/<comment_id>/set_upvoted/. Now if I have that route, it would be logic to have a comments app. If I wanna play the refactoring game, this is the time. But I feel lazy so I’m going to do ugly stuff, put the route in the global urls.py

from django.contrib import admin
from django.contrib.auth import views as auth_views
from django.urls import include, path
from hnews.posts import views as posts_views

urlpatterns = [
    path('admin/', admin.site.urls),
    path('posts/', include('hnews.posts.urls')),
    path('accounts/login/', auth_views.LoginView.as_view(), name='login'),
    path('accounts/logout/', auth_views.LogoutView.as_view(), name='logout'),
    path('comments/<int:comment_id>/set_upvoted/', posts_views.set_upvoted_comment, name='set_upvoted_comment')
]

Let’s add a to_dict to our Comment model.

def to_dict(self, user):
    return {
        'content': self.content,
        'how_long_ago': self.how_long_ago(),
        'creator': self.creator.username,
        'upvoted': self.upvotes.filter(user=user).count() > 0,
        'upvote_url': reverse('set_upvoted_comment', kwargs={'comment_id': self.id}),
    }

Now let’s update Post.to_dict

def to_dict(self, user):
    return {
        'title': self.title,
        'how_long_ago': self.how_long_ago(),
        'domain_name': self.get_domain_name(),
        'creator': self.creator.username,
        'upvoted': self.upvotes.filter(user=user).count() > 0,
        'upvote_url': reverse('posts:set_upvoted_post', kwargs={'post_id': self.id}),
        'comments': [comment.to_dict(user) for comment in self.comments.all()]
    }

Let’s update our template now:

<div id="app">
    [[ post.title ]] - [[ post.how_long_ago ]] - [[ post.domain_name ]]
    {% if user.is_authenticated %}
    - <span v-if="post.upvoted">Upvoted</span><span v-else>Not Upvoted</span>
    - <button v-on:click="upvote(post)">Toggle upvoted</button>
    {% endif %}


    {% if user.is_authenticated %}
        <form action="" method="post">
            {% csrf_token %}
            {{ form }}
            <input type="submit" value="Submit" />
        </form>
    {% endif %}
    <ul v-for="comment in post.comments">
        <li>[[ comment.content ]] - [[ comment.how_long_ago ]]</li>
    </ul>
</div>

Let’s try now: http://localhost:8000/posts/1/

I messed up some stuff in my database so I have this error: ’NoneType’ object has no attribute ‘username’. Let’s fix that.

In [2]: user = User.objects.first()In [3]: user
Out[3]: <User: jack>In [6]: Post.objects.filter(creator=None).update(creator=user)
Out[6]: 2

Ok it works now. Let’s add something to upvote the comment.

<div id="app">
    [[ post.title  ]] - [[ post.how_long_ago ]] - [[ post.domain_name ]]
    {% if user.is_authenticated %}
    - <span v-if="post.upvoted">Upvoted</span><span v-else>Not Upvoted</span>
    - <button v-on:click="upvote(post)">Toggle upvoted</button>
    {% endif %}


    {% if user.is_authenticated %}
        <form action="" method="post">
            {% csrf_token %}
            {{ form }}
            <input type="submit" value="Submit" />
        </form>
    {% endif %}
    <ul v-for="comment in post.comments">
        <li>[[ comment.content ]] - [[ comment.how_long_ago ]]</li>
        {% if user.is_authenticated %}
        - <span v-if="comment.upvoted">Upvoted</span><span v-else>Not Upvoted</span>
        - <button v-on:click="upvote(comment)">Toggle upvoted</button>
        {% endif %}
    </ul>
</div>

Ok it’s good for today. Not a very productive day but it’s better than nothing :).

See ya!

A little Hacker News in Django (part 8)

Written by Daniel Dương