Question

I have the following models:

class Profile(models.Model):
    verified = models.BooleanField(default=False)
    primary_phone = models.OneToOneField('Phone', related_name='is_primary', null=True, blank=True)

class Phone(models.Model):
    profile = models.ForeignKey(Profile)
    type = models.CharField(choices=PHONE_TYPES, max_length=16)
    number = models.CharField(max_length=32)

    @property
    def is_primary(self):
        return profile.primary_phone == self

And the following forms:

class PhoneForm(ModelForm):
    class Meta:
        from accounts.models import Phone
        model = Phone
        fields = ('type', 'number', )

which is being used in a modelformset_factory.

I’m rendering the formset like this:

<div class="span-13 last">
    {{ formset.management_form }}
    {% for form in Phones %}
        <div class="span-2">{{ form.type|add_class:'dropdown' }}</div>
        <div class="span-11 last">{{ form.number|add_class:'phone-number' }}</div>
        <div class="clearfix"></div>
    {% endfor %}
</div>

Now what I want to do is to render a radio button in the template to reflect the is_primary property of Phone model. There are two ways to determine this relationship, through Phone model itself or through Profile.primary_phone. But then I’m rendering Phone model as a formset, hence looping over its instances, so I tried to include 'is_primary' in PhoneForm fields, but it did not work since it’s a property.

Any idea how to do this?

UPDATE #1:

I have used jpic approach and tried to render primary as radio buttons:

class PhoneForm(ModelForm):
    primary = forms.BooleanField(widget=forms.RadioSelect( choices=((0, 'False'), (1, 'True')) ))

    class Meta:
        from accounts.models import Phone
        model = Phone
        fields = ('primary', 'type', 'number', )

However, it shows two radio buttons for each instance of Phone while I need it to show only one radio button per instance. I’m going to play around with it for a while and see if I can get it to show correctly.

Answer 1

Instead of:

class Profile(models.Model):
    verified = models.BooleanField(default=False)
    primary_phone = models.OneToOneField('Phone', related_name='is_primary', null=True, blank=True)

class Phone(models.Model):
    profile = models.ForeignKey(Profile)
    type = models.CharField(max_length=16)
    number = models.CharField(max_length=32)

You should have:

class Profile(models.Model):
    verified = models.BooleanField(default=False)

    def primary_phone(self):
        return self.phone_set.get(primary=True)

class Phone(models.Model):
    profile = models.ForeignKey(Profile)
    type = models.CharField(max_length=16)
    number = models.CharField(max_length=32)
    primary = models.BooleanField(default=False)

    def save(self, force_insert=False, force_update=False, using=None):
        if self.primary:
            # clear the primary attribute of other phones of the related profile
            self.profile.phone_set.update(primary=False)
        self.save(force_insert, force_update, using)

That would make your life easier.

If you cannot make this change: a Phone formset is actually a wrapper around many Phone forms. But the field you’re after allows to edit Profile.primary_phone.

So one way of doing it is to do it manually as such:

{% for form in Phones %}
    <input type="radio" name="primary_phone" checked="{% if form.instance == profile.primary_phone %}checked{% endif %}" value="{{ form.instance.pk }}" />
    <!-- snip ... ->

But the problem is that the radio won’t have a value for empty Phone forms, as the value is {{ form.instance.pk }}.

Another way of doing it is to add a checkbox to PhoneForm:

from django import forms

from accounts.models import Phone

class PhoneForm(forms.ModelForm):
    primary = forms.BooleanField(required=False, default=False)

    class Meta:
        model = Phone
        fields = ('type', 'number', )

We’re using a BooleanField here because for each Phone form, primary is to be set or not. But still, you’ll have to render it yourself:

{% for form in Phones %}
    <input type="checkbox" name="{{ form.prefix }}-primary" checked="{% if form.instance == profile.primary_phone %}checked{% endif %}" value="true" />
    <!-- snip ... ->

But then, you need javascript to ensure only one radio is checked at the time, e.g. with jQuery:

$('input[type=checkbox]').change(function() {
    $('input[type=checkbox][checked=checked]').attr('checked', '');
    $(this).attr('checked', 'checked');
});

Of course, you should update the selectors in this example above to ensure only “primary phone” checkboxes are affected.

Finally, to connect the checkbox, something like this might work:

class PhoneForm(forms.ModelForm):
    primary = forms.BooleanField(required=False)

    def __init__(self, *args, **kwargs):
        super(PhoneForm, self).__init__(*args, **kwargs)

        if self.instance.is_primary:
            self.data['primary'] = True

    def save(self, *args, **kwargs):
        super(PhoneForm, self).save(*args, **kwargs)

        if self.cleaned_data['primary']:
            self.profile.primary_phone = self
            self.profile.save()