[newforms-admin] allow override of forms.BaseForm as a base class for admin forms

[Honza Král <Honza.Kral@…>]

I have a model that need some custom validation across multiple fields. To achieve that it would be best to allow overriding of base form like this:

from django import newforms as forms
class SomeModelForm( forms.BaseForm ):
    def clean( self ):
        data = self.cleaned_data
        if I_not_like_something( data ):
            raise forms.ValidationError, _( "Something is wrong" )
        return data

class SomeModelOptions( admin.ModelAdmin ):
    base_form = SomeModelForm

admin.site.register( SomeModel, SomeModelOptions )

Since newforms.models.form_for_instance and newforms.models.form_for_instance already provide this functionality, its just a matter of adding the variable to ModelAdmin.

This approach would also solve #4507

[anonymous]

+1 on this -- very easy patch provides significant new functionality.

This seems to me the easiest way of handling what I assume is a very common use case of validating across multiple fields in the admin.

[Petr Marhoun <petr.marhoun@…>]

I attached a new patch which works also for inline formsets.

[Petr Marhoun <petr.marhoun@…>]

I don't think that attached patches solve #4507 - see ​my comments.

[Honza Král]

fixed by add_form and change_form hooks