How to over ride the get context data method in view

[Ahmed Khairy]

I am currently trying to create a like button for my posts in Django

I have reached to the part where I can add a like but I am facing difficulty writing the code related to the view which linking the PostListView if there is user who liked it or not. I am getting an error: page Error 404 although everything is correct

this the views: 

class PostListView(ListView):

    model = Post

    template_name = "score.html"

    ordering = ['-date_posted']

    context_object_name = 'posts'

    queryset = Post.objects.filter(admin_approved=True)

    paginate_by = 5

    def get_context_data(self, **kwargs):

        post = get_object_or_404(Post, id=self.request.POST.get('post_id'))

        context = super(PostListView, self).get_context_data(**kwargs)

        context['posts'][0].likes.filter(id=self.request.user.id).exists()

        is_liked = False

        if post.likes.filter(id=self.request.user.id).exists():

            is_liked = True

        context = {'post': post,

                   'is_like': is_liked,

                   }

        return context

def like_post(request):

    post = get_object_or_404(Post, id=request.POST.get('post_id'))

    is_liked = False

    if post.likes.filter(id=request.user.id).exists():

        posts.likes.remove(request.user)

        is_liked = False

    else:

        post.likes.add(request.user)

        is_liked = True

    return HttpResponseRedirect(post.get_absolute_url())

This is the model 

class Post(models.Model):
    designer = models.ForeignKey(User, on_delete=models.CASCADE)
    title = models.CharField(max_length=100)
    date_posted = models.DateTimeField(default=timezone.now)
    likes = models.ManyToManyField(User, blank=True, related_name='likes')

    def __str__(self):
        return self.title

Here is the

path('like/', like_post, name='like_post'),

here is the template: 

{% extends "base.html"%} {% block content %} {% for post in posts %}

<div style="padding-top: 200 px;"><strong>{{post.title}}</strong></div>

<form action="{% url 'score:like_post'%}" method="POST" class="ui form">
  {% csrf_token %} {% if is_like %}
  <input type="hidden" name="post_id" value="{{post.id}}" />
  <button class="ui button positive" type="submit">Unlike</button>
  {% else %}
  <button class="ui button negative" type="submit">Like</button>
  {% endif %}
</form>
<strong>Likes </strong>

{% endfor %} {% endblock content %} 

[Andréas Kühne]

Hi,

There are a couple of errors in your code:

1. You are using a ListView and then trying to get an individual post? That is really strange

2. In your get_context_data method - you first get the context data, update it and then you set it to a new dict, so everything is reset in the dict.

3. you are trying to get the absolut url for your post, but aren't showing any post detail view.

Regards,

Andréas

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[Ahmed Khairy]

Hi Andréas Kühne,

Regarding the first error

I have a list of posts in the listView and want to add the like button to each post so how should I fix it? 

Thank you 

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[Andréas Kühne]

Hi again,

Bare with me - this is just written in this email - so:

1. Your listview is paginated by 5, so it will only show 5 posts - that's good for this exercise and how I would solve it.

2. Rewrite your get_context_data method to iterate over the posts:

    def get_context_data(self, **kwargs):
        context_data = super(PostListView, self).get_context_data(**kwargs)
        for post in context_data['posts']:

            post.is_liked = post.likes.filter(user=user).exists()

        return context

So now your page should show. In the page template:

% extends "base.html"%} {% block content %} {% for post in posts %}

<div style="padding-top: 200 px;"><strong>{{post.title}}</strong></div>

<form action="{% url 'score:like_post'%}" method="POST" class="ui form">

<input type="hidden" name="post_id" value="{{post.id}}" />

{% csrf_token %} {% if is_like %}
   <button class="ui button positive" type="submit">Unlike</button>

  {% else %}
  <button class="ui button negative" type="submit">Like</button>
  {% endif %}
</form>

{% endfor %} {% endblock content %} 

Something like this should give you the functionality you want - however it's still a bit cumbersome.

Regards,

Andréas

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[Ahmed Khairy]

Hi There, 

I have rewritten the get_context_data method to be like this but I am getting name 'user' is not defined:

class PostListView(ListView):

    model = Post

    template_name = "score.html"

    ordering = ['-date_posted']

    context_object_name = 'posts'

    paginate_by = 5

    def get_context_data(self, **kwargs):

        context_data = super(PostListView, self).get_context_data(**kwargs)

        for post in context_data['posts']:

            post.is_liked = post.likes.filter(user=user).exists() <----- name 'user' is not defined

        return context

I am also using this template just for testing till fix the issue 

Thank you Andreas with me

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[Yamen Gamal Eldin]

I haven't seen any definition for user within ur function, so 

Change this 

post.is_liked = post.likes.filter(user=user).exists()

To this

post.is_liked = post.likes.filter(user=request.user).exists()

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[Ahmed Khairy]

still showing the same error

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[Andréas Kühne]

Hi,

We can't solve all of your problems for you :) But that being said - in the get_context_data you don't have a parameter for the request, however in all CBV you get the request as a variable on the CBV itself - so change:

post.is_liked = post.likes.filter(user=request.user).exists()

To:

post.is_liked = post.likes.filter(user=self.request.user).exists()

Regards,

Andréas

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