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In the Django tutorial:

 {% for choice in question.choice_set.all %}

I couldn't find a brief explanation for this. I know that in the admin.py file, I have created a foreign key of Question model on the choice model such that for every choice there is a question.

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    take a look here: stackoverflow.com/questions/2048777/… I was looking for it a few minutes ago ;-) Commented Jul 31, 2015 at 12:55
  • the .all is the same 'all' as when you do Choice.objects.all() i.e. the queryset method. see @wim's answer for why Commented Jul 31, 2015 at 13:28
  • @Tom83B +1 for pointing to the right question with nice explanation. Commented Mar 12, 2020 at 15:28

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That's the Django metaclass magic in action! Since you have a foreign key from Choice model to the Question model, you will automagically get the inverse relation on instances of the question model back to the set of possible choices.

question.choice_set.all is the queryset of choices which point to your question instance as the foreign key.

The default name for this inverse relationship is choice_set (because the related model is named Choice). But you can override this default name by specifying the related_name kwarg on the foreign key:

class Choice(models.Model): ... question = models.ForeignKey(Question, related_name='choices')
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2 Comments

@wim good explanation, thanks. This is really confusing in the Django tutorial documentation, because you're initially working with two db class models called Question and Choice, so choice_set.all makes you think there should be a method in your Choice class called choice_set or something.
This seems like a great place to update and improve the (already excellent) documentation.

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