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I am sorry if this is a duplicate, but I did not find any answer to my question.

My issue below

I am really struggling to understand how to customise my views when using ListView. I read the Django documentation, but I find it very brief.

What I would like to do is to count the questions for each topic and return the topic with the most questions. I would be able to count the number of questions for each topic with the following line of code in my models.py (Topic class):

def questions_count(self):
 return Question.objects.filter(question__topic = self).count()

However, I would like to return only the most popular Topic and the number of questions.

Using a function-based view, I would loop over the topics, and I would create two variables storing the topic name and the number of questions. However, with the ListView I do not know whether to use get_context_data(), get_queryset() or something else.

My view class:

class TopicsView(ListView):
 model = Topic
 context_object_name = 'topics'
 template_name = 'home.html'

My models:

class Topic(models.Model):
 name = models.CharField(max_length=30, unique=True)
 description = models.CharField(max_length=100)

class Question(models.Model):
 ....
 topic = models.ForeignKey(Topic, related_name='questions', on_delete=models.CASCADE) 
 ....

You might want to try using .annotate() to get the count of Questions associated with each Topic:

from django.db.models import Count

topics_count = Topics.objects.annotate(count_of_questions=Count('question'))

Each Topic object will have a new attribute count_of_questions which is the total number of questions associated with each Topic.

In your ListView:

class TopicsView(ListView):
 model = Topic
 context_object_name = 'topics'
 template_name = 'home.html'

 def get_queryset(self):
 queryset = super(TopicsView, self).get_queryset()
 queryset = queryset.annotate(count_of_questions=Count('question'))

Then you should be able to use dictsortreversed to do the following in your template, which should return the topic with the most questions first:

% for t in topics
 t.count_of_questions 
% endfor %

There's a similar question and answer in the following SO Q&A

In the end, I have managed to do it through the get_context_data() function. This is how my solution looks like:

def get_context_data(self, **kwargs):
 context = super().get_context_data(**kwargs)

 mostQuestions = context['object_list'][0].questions_count()
 mostQuestionsTopic = context['object_list'][0]

 for topic in context['object_list']:
 if topic.questions_count() > mostQuestions:
 mostQuestions = topic.questions_count()
 mostQuestionsTopic = topic

 context['mostQuestions'] = mostQuestions
 context['mostQuestionsTopic'] = mostQuestionsTopic

 return context

Is there a more efficient solution?