Question

I have the following models,

### models.py

class Foo(models.Model):
    name = models.CharField(max_length=200)

class Bar(models.Model):
    foo = models.ForeignKey(Foo)
    baz = models.ManyToManyField(Baz, through='Between')

class Baz(models.Model):
    name = models.CharField(max_length=200)

class Between(models.Model):
    foo = models.ForeignKey(Foo)
    bar = models.ForeignKey(Bar)
    CHOICES = (
        ('A', 'A'),
        ('B', 'B'),
        ('C', 'C'),
        )
    value = models.CharField(max_length=1, choices=CHOICES)

and I have the following forms,

### forms.py
class FooForm(forms.ModelForm):
    class Meta:
        model = Foo

class BarForm(forms.ModelForm):
    baz = forms.ModelMultipleChoiceField(widget=forms.CheckboxSelectMultiple(),
                                         queryset=Baz.objects.all())
    class Meta:
        model = Bar
        exclude = ('foo',)


BarFormSet = inlineformset_factory(Foo, Bar, form=BarForm, can_delete=False)

Now, this works great in that I can render a single Foo and I get a number of inline forms for Bar. This renders is that the inline BarForm renders all the options of Baz as checkboxes.

What I would like is for each record of Baz to be rendered as a set of radio buttons representing the possible choices for value—along with a “N/A” choice—so that if A,B, or C is selected then the relationship to Baz is implied. But by default there doesn’t seem to be a nice way of doing this with completely re-implementing RadioSelect or implementing a completely new widget, but I would like to follow the path of least resistance.

Hopefully I am making things clear.

Answer 1

My solution was to create SuperForm which allows subforms. The total solution is not quite generic for everyone but I did my best here to take what I was using and make it a bit more general.

Here is models.py:

from django.db import models

class Enemy(models.Model):
    name = models.CharField(max_length=200)
    def __unicode__(self):
        return self.name

class Hero(models.Model):
    name = models.CharField(max_length=200)
    enemy = models.ManyToManyField(Enemy, through='Relationship', blank=False, null=False)
    def __unicode__(self):
        return self.name

class Relationship(models.Model):
    hero = models.ForeignKey(Hero)
    enemy = models.ForeignKey(Enemy)
    ENEMY_TYPE_CHOICES = (
        ('G', 'Good'),
        ('B', 'Bad'),
        ('U', 'Ugly'),
        )
    enemy_type = models.CharField(max_length=1, choices=ENEMY_TYPE_CHOICES)

    def __unicode__(self):
        return u"{0} {1} {2}".format(self.hero, self.strength, self.relationship)

Here is what is in my forms.py:

from models import *
from django import forms
from django.forms.formsets import formset_factory, BaseFormSet
from django.forms.models import inlineformset_factory, BaseModelFormSet
from django.utils.safestring import mark_safe


class SuperForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        self.formsets = []
        super(SuperForm, self).__init__(*args, **kwargs)

    @property
    def is_bound(self):
        return self._is_bound or \
            any([subformset.is_bound for subformset in self.formsets])

    @is_bound.setter
    def is_bound(self, value):
        self._is_bound = value

    def has_changed(self):
        return bool(self.changed_data) or \
            any([subformset.has_changed() for subformset in self.formsets])

    def update_empty_permitted(self, subformset):
        empty_permitted = not self.has_changed()
        for subformset in self.formsets:
            for form in subformset:
                form.empty_permitted = empty_permitted

    def is_valid(self):
        subforms_valid = True
        for subformset in self.formsets:
            self.update_empty_permitted(subformset)
            sfserrors = [err for err in subformset.errors if err]
            if bool(sfserrors):
                subforms_valid = False

        return subforms_valid and super(SuperForm, self).is_valid()

class RelationshipForm(forms.ModelForm):
    enemy = forms.ModelChoiceField(queryset=Enemy.objects.all(),
                                   widget=forms.HiddenInput(),
                                   required=True)
    enemy_type = forms.ChoiceField(label="", widget=forms.RadioSelect,
                                 choices=Relationship.ENEMY_TYPE_CHOICES,
                                 required=True)
    def name(self):
        pk = self['enemy'].value()
        return self.fields['enemy'].queryset.get(pk=pk)

    class Meta:
        model = Relationship
        exclude = ('hero', 'enemy_type',)


RelationshipFormSet = formset_factory(RelationshipForm, extra=0, can_delete=False)

class HeroForm(SuperForm):
    def __init__(self, *args, **kwargs):
        super(HeroForm, self).__init__(*args, **kwargs)

        initial=[dict(enemy=enemy.pk) for enemy in Enemy.objects.all()]
        self.relationship_formset = RelationshipFormSet(initial=initial, prefix=self.prefix, data=kwargs.get('data'))
        self.formsets.append(self.relationship_formset)

    class Meta:
        model = Hero
        exclude = ('enemy',)

HeroFormSet = formset_factory(HeroForm, extra=1, can_delete=False)

Here is the views.py:

from django.views.generic import TemplateView
from django.views.generic.edit import FormMixin
from forms import *

class HeroView(FormMixin, TemplateView):
    template_name = "formfun/hero.html"
    form_class = HeroFormSet

    def get_context_data(self, **kwargs):
        context = super(HeroView, self).get_context_data(**kwargs)
        context['formset'] = HeroFormSet()
        return context

    def form_valid(self, form):
        return render_to_response({'form':form, 'valid': True})

    def form_invalid(self, form):
        return render_to_response({'form':form, 'valid': False})

And here is the template as I render it:

{% extends "base.html" %}
{% block title %}form fun{% endblock %}

{% block content %}
<form>
  {% for form in formset %}
  {{ form.as_p }}
  {% for subform in form.relationship_formset %}
  <label for="id_{{ subform.html_name }}_0" class="label50">{{ subform.name }}</label>
  {{ subform.as_p }}
  {% endfor %}
  {% endfor %}
</form>
{% endblock content %}