ArrayField.has_changed() returns True for unchanged fields

[tejinderss]

I have models Foo and Bar for example:

    from django.contrib.postgres.fields import ArrayField

    class Foo(models.Model):
        field = models.CharField(max_length=200)

    class Bar(models.Model):
        foo = models.OneToOneField(Foo)
        required_field = models.CharField(blank=False)
        array_field = ArrayField(models.CharField(max_length=50, blank=true), blank=True, null=True)

and in the admin.py i have:

    class BarInline(admin.StackedInline):
        model = Bar

    @admin.register(Foo)
    class FooAdmin(admin.ModelAdmin):
        inlines = [BarInline]

Now the issue is on the save form in admin, if i try to create foo instance without providing any bar data in barinline form, i get error that bar's required field is required and if i make all fields optional, it creates the bar instance anyway without any data. I have played with min_num and max_num but in vain.

[Tim Graham]

I can't reproduce the issue given the minimal models and admin that you provided.

[tejinderss]

This bug seems to be valid only when the postgres arrayfield is used in the inline model

[Tim Graham]

The problem is ArrayField.has_changed() returning True even though the field wasn't modified.

[vinay karanam]

I've raised a ​PR implementing necessary changes.

[Tim Graham <timograham@…>]

In 6a1957b:

Fixed #28950 -- Fixed ArrayField.has_changed() for empty values.