In Django is there a way to display choices as checkboxes?

In the admin interface and newforms there is the brilliant helper of being able to define choices. You can use code like this:

APPROVAL_CHOICES = (
    ('yes', 'Yes'),
    ('no', 'No'),
    ('cancelled', 'Cancelled'),
)

client_approved = models.CharField(choices=APPROVAL_CHOICES)

to create a drop down box in your form and force the user to choose one of those options.

I'm just wondering if there is a way to define a set of choices where multiple can be chosen using checkboxes? (Would also be nice to be able to say that the user can select a maximum number of them.) It seems like it's a feature that is probably implemented, it's just I can't seem to find it in the documentation.

In terms of the forms library, you would use the MultipleChoiceField field with a CheckboxSelectMultiple widget to do that. You could validate the number of choices which were made by writing a validation method for the field:

class MyForm(forms.Form):
    my_field = forms.MultipleChoiceField(choices=SOME_CHOICES, widget=forms.CheckboxSelectMultiple())

    def clean_my_field(self):
        if len(self.cleaned_data['my_field']) > 3:
            raise forms.ValidationError('Select no more than 3.')
        return self.cleaned_data['my_field']

To get this in the admin application, you'd need to customise a ModelForm and override the form used in the appropriate ModelAdmin.

@JonnyBuchanan gave the right answer.

But if you need this in the django admin for many models, and you're (like me) too lazy to customize a ModelForm and ovverride the right methods inside the ModelAdmin class, you can use this approach:

http://www.abidibo.net/blog/2013/04/10/convert-select-multiple-widget-checkboxes-django-admin-form/