ChoiceField/ModelChoiceField always returns strings, regardless of type in choices

[Robert Coup]

f = ChoiceField(choices=((1,'1'), (2,'2')))
f.clean('1')
u'1'
# expected: 1 (integer)

While normally this doesn't cause problems (models are pretty good about accepting strings) it can be extra hassle for custom forms.

The attached patch changes the behaviour of ChoiceField and ModelChoiceField to return exactly what was specified in choices (be it integer, string, unicode, whatever).

[Robert Coup]

For the archives, originally kicked off from #3729

[Robert Coup]

a slightly cleaner implementation

[Malcolm Tredinnick]

I'm not comfortable with this change. We have a policy that whenever a string is involved, be it a UTF-8 bytestring or a Unicode string, Django will convert it a unicode object for internal use. This is breaking out of that policy by trying to preserve the str type. It's a bit inconsistent.

Is it satisfactory to pass strings_only=True to smart_unicode() instead of removing the smart_unicode() calls? That would make me happier.

[Philippe Raoult]

likely related to #5247.

[Robert Coup]

#5247 isn't a duplicate - this ticket is related to how the choices are evaluated in ChoiceField.clean(), the other ticket is related to how the choices get evaluated for display in the widget render method.

[Robert Coup]

I hadn't seen strings_only before, but i have some reservations about it - namely, it should probably be called ignore_none_and_int. That prevents objects, doubles, booleans, Decimals, etc as being keys.

Would doing isinstance(value, str) and unicode'ing only those be acceptable? (Patch .3 does it this way)

[Robert Coup]

Forces strings to unicode

[evenrik]

Use the new TypedChoiceField to solve this issue.

[klrfin@…]

There's no TypedMultipleChoiceField.

[Russell Keith-Magee]

r14829 added a TypedMultipleChoiceField, making this a wontfix.