Django view works for only one url ,despite the appropriate queryset being generated in the view

Question

I am trying to access a lesson belonging to a course in my application. When I use the url http://127.0.0.1:8000/courses/1/lessons/1/" the appropriate results get returned. However when I try anyother url such as "http://127.0.0.1:8000/courses/1/lessons/2/" I get an error instead Result for http://127.0.0.1:8000/courses/1/lessons/1/

{
    "id": 1,
    "title": "course 1 lessson 1",
    "owner": 1,
    "course": 1
}

Expected Result for http://127.0.0.1:8000/courses/1/lessons/2/

{
    "id": 1,
    "title": "course 1 lessson 2",
    "owner": 1,
    "course": 1
}

actual result

{
    "detail": "Not found."
}

URL

 path('courses/<int:pk>/lessons/<int:lpk>/', LessonDetail.as_view()),

Serializer

class LessonSerializer(serializers.ModelSerializer):
    class Meta:
        model = Lesson
        fields = ['id','title','owner','course']

view

class LessonDetail(generics.RetrieveUpdateDestroyAPIView):
    # queryset = Lesson.objects.all()
    serializer_class = LessonSerializer
    def get_queryset(self):
       # GET PK FROM URL USING KWARGS
        course_pk = self.kwargs['pk']
        lesson_pk = self.kwargs['lpk']
        qs = Lesson.objects.filter(course_id=course_pk,id=lesson_pk)
        print(qs)
        return qs

model

class Lesson(models.Model):
    title = models.CharField(max_length=150, help_text='Enter course title')
    video = models.CharField(max_length=150, help_text='Enter course title', null=True)
    thumbnail = models.CharField(max_length=150, help_text='Enter course title', null=True)
    pub_date = models.DateField(null=True, blank=True)
    course = models.ForeignKey('Course', on_delete=models.CASCADE,related_name='lessons')
    description = models.TextField(max_length=1000, help_text='Enter a brief description of the course')
    owner = models.ForeignKey( settings.AUTH_USER_MODEL, on_delete=models.CASCADE,  )

The view returns the object <QuerySet [<Lesson: course 1 lessson 1>]> for http://127.0.0.1:8000/courses/1/lessons/1/ and <QuerySet [<Lesson: course 1 lessson 2>]> for http://127.0.0.1:8000/courses/1/lessons/2/. To my inexperienced eye, it looks as if the view is returning the appropriate queryset but it fails to produce any results for the second url. How can I make it respond appropriately.

Answer 1

You also can use generics.RetrieveAPIView for DetailView. Than declare queryset and serializer_class.