Re: Django form(s) for intermediary models

Hi,

What you want to do here is use a Django "Formset" which contains your
ModelForms. Since you want to show one form per person
regardless of whether they are a member or not we can't use the
modelformset_factory() and will have to do some manipulation of the
initial data using the formset_factory() function instead. I haven't
actually run and tested the code below (user beware) but you'll need
to do something similar in order to do what you're describing.

See:
http://docs.djangoproject.com/en/dev/topics/forms/formsets/
http://docs.djangoproject.com/en/dev/topics/forms/modelforms/#model-formsets

Using the Membership form (I called it MembershipForm) from the previous poster:

from django.forms.models import formset_factory

def myview(request, group_id):
group = Group.objects.get(pk=group_id)

MembershipFormset = formset_factory(form=MembershipForm, extra=0)
if request.method == 'POST':
formset = MembershipFormset(request.POST)
if formset.is_valid():
# since the formset itself isn't a ModelFormset
# we need to loop over the individual ModelForms
# and save() them.
for form in formset.forms:
form.save()
# Do something
else:

# Make a person_id to membership mapping.
memberships = dict(map(lambda m: (m.person_id, m),
groups.membership_set.all()))
initial = {}
We need to order by pk (or some other field) here so that the
form indexes match.
for i,person in enumerate(Person.objects.all().order_by("pk")):
prefix = form.get_default_prefix()
membership = memberships.get(person.pk, None)

# Here we create the initial data.
# Add data for the each initialized form here.
# initial data is needed for every person in order
# to set the number of forms.
initial.update({
'%s-%s-person' % (prefix, i): person if membership else None,
'%s-%s-date_joined' % (prefix, i):
membership.date_joined if membership else None,
})
formset = MembershipFormset(initial=initial)

# do something

On Wed, Jan 26, 2011 at 8:46 AM, aa56280 <aa56280@gmail.com> wrote:
>> In your case it would become something like:
>>
>> class Membership(ModelForm):
>>         class Meta:
>>                 model = Membership
>>                 fields = ('person', 'date_joined')
>>                 widgets = {
>>                         'person' : CheckBox(),
>>                         'date_joined': TextInput(),
>>                 }
>
> I need a form for each person though because a Group could have many
> members.
>
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--
Ian

http://www.ianlewis.org/

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