Try next view in Django URL dispatcher

Question

We have the following URL configuration in Django.

Django will try to match the URL with the rules down below. Once it finds a match, it will use the appropriate view and lookup the object in the model.

The thing is, once it finds a match in the URL pattern, it will match the view. But once the object in the view can't be found, it will return a page not found (404) error.

urls.py:

from django.urls import path

from . import views

urlpatterns = [
    path('articles/<slug:category>/<slug:editor>/', views.ArticleByThemeView.as_view(), name='articles_by_editor'),
    path('articles/<slug:category>/<slug:theme>/', views.ArticleDetailView.as_view(), name='articles_by_theme')
]

views.py

class ArticleByThemeView(ListView):
    """
    List all articles by a certain theme; "World War 2".
    """
    model = Article
    
    def dispatch(self, request, *args, **kwargs):
        try:
            # Check if the theme_slug matches a theme
            theme = ArticleTheme.objects.get(slug=self.kwargs['theme_slug'])
        except ArticleTheme.DoesNotExist:
            # Theme does not exist, slug must be an article_slug
            return redirect(
                'article_detail',
                category_slug=category_slug
                article_slug=theme_slug
            )
        return super().dispatch(request, *args, **kwargs)

class ArticleDetailView(DetailView):
    """
    Detailview for a certain article
    """
    model = Article

    def get_object(self):
        return get_object_or_404(
            Article,
            category__slug=self.kwargs['category_slug'],
            slug=self.kwargs['article_slug']
        )

We have the following URL patterns, we can sort articles either by the editor or by theme. We do this to create a logical URL structure for SEO purposes.

Is there any way we can redirect to another view once the object isn't found?

Can we modify the dispatch method to return to the URL patterns and find the following matching rule?

Multiple routes pointing to the same view, never thought about this. I'll give it a try and let you know. — Kevin D., Jan 30 '23 at 13:23

score 3 · Answer 1 · answered Jan 30 '23 at 09:59

3

What about redirection like this:

def articles_by_editor(request, category, editor):
    try:
        article = Article.objects.get(category=category, editor=editor)
        # return article
    except Article.DoesNotExist:
        # redirect to another view
        return redirect('articles_by_theme', category=category)

answered Jan 30 '23 at 09:59

Amin

2,605
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15

Even though this sounds like a great solution, it ends up in a redirect loop. Not entirely sure why, I get a series of 302 in my console... – Kevin D. Jan 30 '23 at 14:24
It does work however when I redirect to the home page ie. ('/') – Kevin D. Jan 30 '23 at 14:27
do you redirect in `articles_by_theme` too ? – Amin Jan 30 '23 at 14:28
Even though we redirect to 'articles_by_theme', it catches a redirect to itself. I'll update the question with some more context. Im currently overriding dispatch method on a listview. – Kevin D. Jan 30 '23 at 14:32
Just updated the answer to include the Class Based views I'm using. – Kevin D. Jan 30 '23 at 14:48

score 0 · Answer 2 · edited Jul 06 '23 at 11:05

Based on the suggestion from Sunderam Dubey, I wrote a function view, which uses two different routes to the same view.

urls.py:

from django.urls import path

from . import views

urlpatterns = [
    path('articles/<slug:category>/<slug:slug>/', views.article_theme_or_detail_view, name='article_by_theme'),
    path('articles/<slug:category>/<slug:slug>/', views.article_theme_or_detail_view, name='article_detail')

]

views.py:

def article_theme_or_detail_view(
    request,
    category_slug,
    slug=None
):
    """
    This view could either be for a theme view or detailview,
    depending on the slug.
    """
    try:
        # Check if the slug represents a theme
        theme = ArticleTheme.objects.get(slug=slug)
        article_list = Article.object.filter(theme=theme)
        
        # Add context
        context = {
            'theme': theme,
            'article_list': article_list
        }

        # Render the template with context
        return render(
            request,
            'article_by_theme.html',
            context
        )
    except ArticleTheme.DoesNotExists:
        # The theme does not exist so the slug must be for a detail view
        context = {
            article = Article.objects.get(slug=slug)
        }

        return render(
            request,
            'article_detail.html',
            context
        )

To do:

Remove one of the URL routes

Try next view in Django URL dispatcher

2 Answers2