How to structure a url to filter if a query string parameter exists in Django

Question

I am trying to filter my 'Posts' model by a parameter passed into a query string in the url. If this parameter is not given, I want the url to just return all posts.

To my (obviously incorrect) understanding, the following is how it should work:

urls.py:

path('feed?category=<str:category>', views.Posts.as_view())

views.py:

def Posts(APIView):
    def get(self, request, **kwargs):
        if self.kwargs['category']:
            queryset = Post.objects.filter(category_name = self.kwargs['category'])
        else:
            queryset = Post.objects.all()

With the above code, I would expect that by requesting a url .../feed, the view would set the queryset to all posts, however if I entered a url .../feed?category=x it would only return posts of this category.

Currently, the program does not function as such. How would I accomplish this functionality?

Thanks, Grae

path only checks the path of the URL, the part after the ? is not the path, that is the query string, so you can not filter with that in the path. — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Sep 30, 2020 at 18:36

willeM_ Van Onsem · Accepted Answer · 2020-09-30 18:40:09Z

2

path only checks the path of the URL, the part after the ? is not the path, that is the query string [wiki], so you can not filter with that in the path. The query string is stored in request.GET a dictionary-like object.

You thus define the path as:

path('feed/', views.PostView.as_view())

and in the view, you can filter with:

def PostView(APIView):
    model = Post

    def get_queryset(self, *args, **kwargs):
        queryset = super().get_queryset(*args, **kwargs)
        if 'category' in self.request.GET:
            return queryset.filter(category_name=self.request.GET['category'])
        return queryset

Note: In Django, class-based views (CBV) often have a …View suffix, to avoid a clash with the model names. Therefore you might consider renaming the view class to PostView, instead of ~~Posts~~.

answered Sep 30, 2020 at 18:40

willeM_ Van Onsem

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3 Comments

Peter Jordanson Over a year ago

If the query string is a dictionary item then can I not access the 'category' variable using self.kwargs['category']?

Peter Jordanson Over a year ago

Would it work to instead use: if 'category' in self.request.kwargs ?

willeM_ Van Onsem Over a year ago

@GraeCumming: no, a request object has no .kwargs, only the view has. The self.kwargs do not contain the items in the querystring, only the path variables.

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