Django M2MFields 'through' widgets

Question

Are there exists any examples of Django widgets which can be useful for ManyToManyFields with 'through' attributes? For example, i have these models (got the source from django documentation):

    from django.db import models

    class Person(models.Model):
        name = models.CharField(max_length=128)

        def __str__(self):              # __unicode__ on Python 2
            return self.name

    class Group(models.Model):
        name = models.CharField(max_length=128)
        members = models.ManyToManyField(Person, through='Membership')

        def __str__(self):              # __unicode__ on Python 2
            return self.name

    class Membership(models.Model):
        person = models.ForeignKey(Person, on_delete=models.CASCADE)
        group = models.ForeignKey(Group, on_delete=models.CASCADE)
        date_joined = models.DateField()
        invite_reason = models.CharField(max_length=64)

Obvisously, standart ModelMultipleChoiceField won't work here. I need to populate 'date_joined' , and 'invite_reason' while adding. Which is the simpliest way to achieve this?

If the answer I posted is not satisfying, could you please explain why, and what you are expecting? Thanks. — Antoine Pinsard, Mar 04 '16 at 12:43

Antoine Pinsard · Accepted Answer · 2016-02-26T13:14:01.230

This is a bit too complex for a simple widget. I can't even imagine how it would look like. You will have to use inline formsets for that purpose.

This should give something like this:

from django.forms import inlineformset_factory

MembershipFormSet = inlineformset_factory(Group, Membership, fields=(
    'person', 'date_joined', 'invite_reason'))
group = Group.objects.get(pk=group_id)
formset = MembershipFormSet(instance=group)

Within django.contrib.admin, you can use inlines with InlineModelAdmin.

Django M2MFields 'through' widgets

1 Answers1