Model.get_FOO_display() does not work correctly with inherited choices.

[Yash Jhunjhunwala]

Given a base model with choices A containing 3 tuples
Child Model inherits the base model overrides the choices A and adds 2 more tuples
get_foo_display does not work correctly for the new tuples added

Example:

class A(models.Model):
   foo_choice = [("A","output1"),("B","output2")]
   field_foo = models.CharField(max_length=254,choices=foo_choice)
   class Meta:
       abstract = True

class B(A):
   foo_choice = [("A","output1"),("B","output2"),("C","output3")]
   field_foo = models.CharField(max_length=254,choices=foo_choice)

Upon invoking get_field_foo_display() on instance of B ,
For value "A" and "B" the output works correctly i.e. returns "output1" / "output2"
but for value "C" the method returns "C" and not "output3" which is the expected behaviour

[Mariusz Felisiak]

Thanks for this report. Can you provide models and describe expected behavior? Can you also check if it's not a duplicate of #30931?, that was fixed in Django 2.2.7.

[Yash Jhunjhunwala]

Replying to felixxm:

Thanks for this report. Can you provide models and describe expected behavior? Can you also check if it's not a duplicate of #30931?, that was fixed in Django 2.2.7.

[Yash Jhunjhunwala]

Added the models and expected behaviour. It is not a duplicate of #30931. Using Django 2.2.9

Replying to felixxm:

Thanks for this report. Can you provide models and describe expected behavior? Can you also check if it's not a duplicate of #30931?, that was fixed in Django 2.2.7.

[Mariusz Felisiak]

Thanks for an extra info. I was able to reproduce this issue, e.g.

>>> B.objects.create(field_foo='A').get_field_foo_display()
output1
>>> B.objects.create(field_foo='B').get_field_foo_display()
output2
>>> B.objects.create(field_foo='C').get_field_foo_display()
C

Regression in 2d38eb0ab9f78d68c083a5b78b1eca39027b279a (Django 2.2.7).