When I've needed something like this I've used a model field
subclass to customize the formfield() method. I've subclassed
models.ManyToManyField, but I would expect the approach to
work on models.ForeignKey as well. formfield is called to
instantiate a forms field when you instantiate the model form.
I also use this as an opportunity to override the widget, to get
checkboxes, but that's optional.
When you call your superclass's formfield method, you add things
like 'queryset' to the keyword arguments (and, in my case, 'widgit').
I do it by making a dictionary for my additions, then update it with
the kwargs that I get, before passing it (with **) to the superclass
method.
The queryset will be used to compose the set of choices (or at least
it is for ManyToManyField), so you can add filter clauses to limit it
as you like, though access to data from the request will take further
research. It may be that between form instantiation and rendering
that you can store a value on the field instance that formfield can
access (it just gets 'self' and normally empty kwargs when called).
I've included my implementation below for reference.
Good luck,
Bill
---------------------------
class ManyToManyCheckboxField(models.ManyToManyField):
def __init__(self, *args, **kwargs):
self.queryset = kwargs.pop('form_queryset', None)
help_text = kwargs.get('help_text', "Check all that apply.")
super(ManyToManyCheckboxField, self).__init__(*args, **kwargs)
self.help_text = help_text
def formfield(self, **kwargs):
defaults = {'widget': forms.CheckboxSelectMultiple}
if self.queryset:
defaults['queryset'] = self.queryset
defaults.update(kwargs)
return super(ManyToManyCheckboxField, self).formfield(**defaults)
---------------------------
On Mon, Mar 1, 2010 at 9:24 AM, AlienBaby <matt.j.war...@gmail.com> wrote:
> Hi.
>
> I have a situation very similar to the following;
>
> [code]
>
> class chars(models.Model):
> name=moels.CharField('Name',max_length=32)
>
> associated_id=models.IntegerField('Associated',blank=False,null=False)
> associated_id.default=0
>
> class ctor(models.Model):
> A=models.ForeignKey(chars,blank=False,null=False)
> B=models.CharField('Text',max_length=512)
>
> [/code]
>
> I would like to generate a form using ModelForm. I started with
>
> [code]
>
> class ctorForm(ModelForm):
> class Meta:
> model=ctor
>
> [/code]
>
> This generates a form, but when rendered the A field of ctor becomes a
> selectable list of all entries in chars.
>
> I would like the A field of the ctorForm to be a selectable list of
> only the entries in chars whose associated_id matches the ID of the
> currently logged in user. (login sessions are handled by django auth,
> or django authopenid)
>
> I'd like to stick to creating the form using ModelForm if it's
> possible.
>
> cheers,
>
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