python - Django Multiple Choice Field / Checkbox Select Multiple

Question

I have a Django application and want to display multiple choice checkboxes in a user's profile. They will then be able to select multiple items.

This is a simplified version of my models.py:

from profiles.choices import SAMPLE_CHOICES

class Profile(models.Model):
    user = models.ForeignKey(User, unique=True, verbose_name_('user'))
    choice_field = models.CharField(_('Some choices...'), choices=SAMPLE_CHOICES, max_length=50)

And my form class:

class ProfileForm(forms.ModelForm):
    choice_field = forms.MultipleChoiceField(choices=SAMPLE_CHOICES, widget=forms.CheckboxSelectMultiple)

    class Meta:
        model = Profile

And my views.py:

if request.method == "POST":
    profile_form = form_class(request.POST, instance=profile)
    if profile_form.is_valid():
        ...
        profile.save()
return render_to_response(template_name, {"profile_form": profile_form,}, context_instance=RequestContext(request))

I can see that the POST is only sending one value:

choice_field u'choice_three' 

And the local vars params is sending a list:

[u'choice_one', u'choice_two', u'choice_three']

All of the form fields display correct, but when I submit a POST, I get an error

Error binding parameter 7 - probably unsupported type.

Do I need to process the multiple choice field further in the view? Is the model field type correct? Any help or references would be greatly appreciated.

Answer 1

The profile choices need to be setup as a ManyToManyField for this to work correctly.

So... your model should be like this:

class Choices(models.Model):
  description = models.CharField(max_length=300)

class Profile(models.Model):
  user = models.ForeignKey(User, blank=True, unique=True, verbose_name='user')
  choices = models.ManyToManyField(Choices)

Then, sync the database and load up Choices with the various options you want available.

Now, the ModelForm will build itself...

class ProfileForm(forms.ModelForm):
  Meta:
    model = Profile
    exclude = ['user']

And finally, the view:

if request.method=='POST':
  form = ProfileForm(request.POST)
  if form.is_valid():
    profile = form.save(commit=False)
    profile.user = request.user
    profile.save()
else:
  form = ProfileForm()

return render_to_response(template_name, {"profile_form": form}, context_instance=RequestContext(request))

It should be mentioned that you could setup a profile in a couple different ways, including inheritance. That said, this should work for you as well.

Good luck.