TypedChoiceField fails to validate properly when used with ArrayField

[Roman Karpovich]

Example model:

from django.contrib.postgres.fields import ArrayField

class ArrayFieldTestModel(models.Model):
    CHOICES = map(lambda x: (x, str(x)), range(10))

    test_field = ArrayField(models.IntegerField(choices=CHOICES), blank=True, null=True)

On form saving we'll got validation error for valid choices:

This is caused by validation ordering:

1. TypedChoiceField clean method called
2. Field clean method called (super)
3. to_python method called, which should transform value to correct, but it doesn't.
4. TypedChoiceField validate called, which raise ValidationError: no such choice. He is trying to find string value in integers array and can't do this.
5. after super clean method, TypedChoiceField is trying to coerce value (it's too late, error was raised before this).

this can be easily fixed by moving _coerce call into to_python.

[Roman Karpovich]

patch for ticket

[Claude Paroz]

I've already struggled with this in the past. Did you check if tests are passing with your proposal?

[Tim Graham]

I observed one test failure with the patch: test_typedchoicefield_special_coerce.

If it's possible to add a test that's not dependent on contrib.postgres, that would be ideal. Of course, we could add that test too.

[Claude Paroz]

It may be that the proper resolution is #27704. Roman, you might be interested to test the patch there.

[Jeroen Dekkers]

The problem with moving _coerce into to_python is that you can coerce to a value not present in choices and clean calls to_python before checking whether the value is in choices. I think the best way to fix this is having SimpleArrayField's to_python call clean on each array item to get the coerced value instead of calling to_python. Pull request with that fix and test case: ​https://github.com/django/django/pull/8358

[Tim Graham]

An alternate ​PR adds ArrayField.clean() that calls base_field.clean().

[Tim Graham <timograham@…>]

In 9dd2443:

Fixed #27161 -- Fixed form validation when an ArrayField's base_field has choices.

[José Jorge Lorenzo Vila]

Any plan to port this to django 1.X? Thanks

[Tim Graham]

No. Per our ​supported versions policy, 1.11 is only receiving data loss and security fixes.