Django ListView dynamic context data - django

Question

Given my models:
class Deck(models.Model):
owner = models.ForeignKey(User, on_delete=models.CASCADE)
name = models.CharField(max_length=255)
class Flashcard(models.Model):
owner = models.ForeignKey(User, on_delete=models.CASCADE)
deck = models.ForeignKey(Deck, on_delete=models.CASCADE)
question = models.TextField()
answer = models.TextField()
In my html template, I want to have a table of all the user's decks, each with their number of cards, e.g. like this:
Deck1: 15
Deck2: 22
Deck3: 100
In my views I have:
def get_context_data(self,**kwargs):
context=super(generic.ListView,self).get_context_data(**kwargs)
context['number_decks']=Deck.objects.filter(owner=self.request.user).count
context['number_cards']=Flashcard.objects.filter(owner=self.request.user,deck__name="Deck1").count
number_decks works as expected.
number_cards also works when I manually type the name in.
But how can I do this without specifying the name, so that in the html template I can just say:
{% for deck in deck_list %}
<td>{{deck.name}}</td>
<td>{{number_cards}}</td>
{% endfor %}
And since I won't know the names of the decks that users will create.
I've tried deck__id=deck.id, but I get zeroes.
How can I change either my models or views to get what I want?

Answer 1

You could just write that as a function to your Deck-Model:
class Deck(models.Model):
owner = models.ForeignKey(User, on_delete=models.CASCADE)
name = models.CharField(max_length=255)
def count_flashcards(self):
fc = Flashcard.objects.filter(deck=self).count()
return fc
And in your template:
{% for deck in deck_list %}
<td>{{deck.name}}</td>
<td>{{deck.count_flashcards}}</td>
{% endfor %}
You might want to use a cached attribute decorator here as well