On Aug 6, 7:13 pm, lingrlongr <keith.ebe...@gmail.com> wrote:
> Having difficulty getting the check_test to work. Can't find any
> examples out there that help. I'll probably have to give a little
> background. I simplified where able to...
>
> class Cat:
> name = CharField
>
> class Category:
> name = ForeignKey(Cat)
> weight = DecimalField
> item = ForeignKey('Item')
>
> class Item:
> name = CharField
>
> Basically Cat is a model of all categories and Category is a model of
> which Cat's are assigned to an item. I did it this way because I want
> to have a "master list" of categories, then have the mapping done in
> other models.
>
> So now I want to build a form at run-time.
>
> def get_form(item):
> fields = dict()
> cat_choices = [(c.id, c.name) for c in Cat.objects.all()]
> for c in cat_choices:
> id, name = c
> checked = bool(item.categoty_set.filter(pk=id).count())
>
> fields['item_cat_%d' % id] = forms.ChoiceField(
> label = name,
> required = False,
> choices = cat_choices,
> widget = forms.CheckboxInput(
> attrs={'value': checked},
> check_test = lambda a: a == checked
> )
> )
> return type('CatSelectForm', (forms.BaseForm,), {'base_fields':
> fields})
>
> So how can I get the correct checkboxes checked at runtime when the
> template is rendered?
>
> Thx.
The closure isn't acting the way you think. Each lambda is bound to
the same `checked` variable, whose value is changed each time through
the loop - so when it is actually evaluated, it has the value of the
last time through.
One way of fixing this is to use a nested function, rather than a
lambda, with a default value:
for c in cat_choices:
...
checked = bool(item.category_set.filter(pk=id).count())
def is_checked(a, checked=checked):
return a == checked
....
widget = forms.CheckboxInput(
attrs={'value': checked},
check_test = is_checked
)
This creates a new function each time, with the default parameter set
to the value of `checked` at the time it was defined.
--
DR.
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