Docs imply that forms.Field.__init__ accepts any keyword arguments

[Gunnlaugur Þór Briem]

At ​https://docs.djangoproject.com/en/dev/ref/forms/fields/ there is this:

class Field(**kwargs)

with no stated constraints on kwargs, thus implying (incorrectly) that any keyword argument can safely be passed to the forms.Field constructor.

That leads to code which worked in previous Django versions but regresses in the current version. The case I have in mind is ​in django-authority's admin.py where the kwargs passed to formfield_callback (which can include request) are passed on to Field.formfield, whose documentation says “All of the kwargs dictionary is passed directly to the form field’s __init__() method” ... and that __init__ method can't include request. So upgrading Django yields this somewhat tricky-to-troubleshoot error in a django-authority admin action:

TypeError: __init__() got an unexpected keyword argument 'request'

  ...
  File "django/forms/models.py", line 170, in fields_for_model
    formfield = formfield_callback(f, **kwargs)
  File "authority/admin.py", line 33, in formfield_for_dbfield
    return db_field.formfield(**kwargs)
  File "django/db/models/fields/__init__.py", line 646, in formfield
    return super(CharField, self).formfield(**defaults)
  File "django/db/models/fields/__init__.py", line 499, in formfield
    return form_class(**defaults)
  File "django/forms/fields.py", line 188, in __init__
    super(CharField, self).__init__(*args, **kwargs)

At some point in this chain, the request keyword argument must be popped out. Presumably directly before the call to Field.formfield. In any case, this requirement should be documented.

(Or forms.Field.__init__ could be changed to tolerate and ignore unknown keyword arguments. But that's a riskier change.)

[Adam Zapletal]

I opened a simple pull request changing

.. class:: Field(**kwargs)

to

.. class:: Field

in the docs. That's how the Form class is documented.

[GitHub <noreply@…>]

In 828b94b:

Fixed #20744 -- Removed hint that arbitrary kwargs are allowed when creating forms.Fields.

[Natalia <124304+nessita@…>]

In f29922b:

[5.0.x] Fixed #20744 -- Removed hint that arbitrary kwargs are allowed when creating forms.Fields.

Backport of 828b94b178736f7882cc6e5cd86b5c8e84b62ece from main