[Django] #31879: Changing a model formset's queryset has no effect when self.forms is accessed

[Django]

#31879: Changing a model formset's queryset has no effect when self.forms is
accessed
-----------------------------------------+--------------------------
               Reporter:  kemar          |          Owner:  nobody
                   Type:  Uncategorized  |         Status:  new
              Component:  Forms          |        Version:  3.1
               Severity:  Normal         |       Keywords:  formsets
           Triage Stage:  Unreviewed     |      Has patch:  0
    Needs documentation:  0              |    Needs tests:  0
Patch needs improvement:  0              |  Easy pickings:  0
                  UI/UX:  0              |
-----------------------------------------+--------------------------
 The Model formsets documentation
 [https://docs.djangoproject.com/en/3.1/topics/forms/modelforms/#changing-
 the-queryset suggests a way to override the default queryset]:

 {{{
 #!python
 class BaseAuthorFormSet(BaseModelFormSet):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.queryset = Author.objects.filter(name__startswith='O')
 }}}

 However, accessing `self.forms` anywhere before `self.queryset` will
 trigger
 
[https://github.com/django/django/blob/e74b3d724e5ddfef96d1d66bd1c58e7aae26fc85/django/forms/models.py#L629
 get_queryset()] and silently populate `self._queryset` with all objects in
 the model so that the next `self.queryset` will have no effect:

 {{{
 #!python
 class BaseAuthorFormSet(BaseModelFormSet):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         for form in self.forms:
             form.empty_permitted = False
         self.queryset = Author.objects.filter(name__startswith='O')  # No
 effect.
 }}}

 Can't tell if it's a bug or an intended behaviour?

-- 
Ticket URL: <https://code.djangoproject.com/ticket/31879>
Django <https://code.djangoproject.com/>
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