Doesn't make sense to have a blank option in dropdowns for non-nullable, non-blankable fields with defaults

[Joeboy]

It makes sense if null or blank is a valid option, or if there's no default (so the user can't mistakenly skip the field). Otherwise it's a (admittedly minor) blemish on your spangly admin section.

[Adrian Holovaty]

Could you paste a sample model? That'd really save some time in verifying and fixing this.

[Simon G. <dev@…>]

Here's one:

from django.db import models

# Create your models here.
class TestModel(models.Model):
    """ Simple Test Model. """
    
    CHOICES = (
        (0, 'State A'),
        (1, 'State B'),
    )
    
    
    emptynotallowed = models.CharField(maxlength=1, choices=CHOICES)
    emptyallowed = models.CharField(maxlength=1, choices=CHOICES, null=True, blank=True)
    defaultemptynotallowed = models.CharField(maxlength=1, choices=CHOICES, default=2)
    defaultemptyallowed = models.CharField(maxlength=1, choices=CHOICES, null=True, blank=True, default=2)

    class Admin:
        pass

So - only emptynotallowed should have the blank drop-down option

[Marc Fargas <telenieko@…>]

From my POV, Field.get_choices() actually adds the BLANK line if the parameter include_blank is True (which is the default) it does not consider self.blank which is the parameter given when defining the field.

The expected behaviour is that if self.blank = False then Field.get_choices must not add the blank line, I will upload a patch following this reasoning in a while.

[Marc Fargas <telenieko@…>]

Patching the behaviour of Field.get_choices() + tests

[Marc Fargas <telenieko@…>]

The attached patch does:

• Change the behaviour of Field.get_choices() so it never adds the Blank option if self.blank = False
• Adds Field.get_choices() tests on the choices tests
• Changes tests/modeltests/manipulators/models.py

The issue reported in this ticket also affects ForeignKeys, on [source:django/trunk/tests/modeltests/manipulators/models.py] there's Album which has a ForeignKey to Musician and on the validation below it expects a blank choice for the relation while it's defined null=False so I stripped the blank choice as the patch above will strip it.

Maybe a second test should be added with a ForeignKey set null=True to make sure that there's always a blank choice ;)

(mtredinnick: this is the patch I owe for #4330 (comment 6) hehe).

[Marc Fargas <telenieko@…>]

ForeignKeys didn't work as expected

[Marc Fargas <telenieko@…>]

Ok, get_choices() has to check self.blank and self.null, if any of both is True the blank choice is given.
I also added tests on ForeignKey for the future. That should be "Ready for Check-in" but I'll leave that in hands of a triager ;))

[Fredrik Lundh <fredrik@…>]

The patch looks fine (well, I'm not great fan of inline "and and and or" constructs), but no longer applies cleanly. Got time to clean it up?

[Thomas Kerpe]

Releasing.... should be patched against newforms

[Thomas Kerpe]

Will port it to newforms (as asked at #django-sprint)

[Karen Tracey]

r6733 accomplished what was being asked for here.