How to disable checkboxes in MultipleChoiceField?

Question

I use MultipleChoiceField in form. It shows me REQUIREMENTS_CHOICES list with checkboxes where user can select and add new requirements to database. Is it possible to disable checkboxes (in my case requirements) which is already in the database? Lets say I have A and C in database so I dont need them.

First value in tulpe is symbol of requirement, second value is the name of requirement.

models.py:

class Requirement(models.Model):
    code = models.UUIDField(_('Code'), primary_key=True, default=uuid.uuid4, editable=False)
    symbol = models.CharField(_('Symbol'), max_length=250)
    name = models.CharField(_('Name'), max_length=250)

forms.py:

REQUIREMENTS_CHOICES = (
        ('A', 'Name A'),
        ('B', 'Name B'),
        ('C', 'Name C'),
        ('D', 'Name D'),
)


class RequirementAddForm(forms.ModelForm):
    symbol = forms.MultipleChoiceField(required=False, widget=forms.CheckboxSelectMultiple, choices=REQUIREMENTS_CHOICES,)

    class Meta:
        model = Requirement
        fields = ('symbol',)

views.py:

def requirement_add(request):
    data = dict()
    if request.method == 'POST':
        form = RequirementAddForm(request.POST)
        if form.is_valid():
            list = dict(REQUIREMENTS_CHOICES) # {'C': 'Name C', 'A': 'Name A', 'B': 'Name B'}
            symbols = form.cleaned_data.get('symbol') # ['A', 'B', 'C']
            requirement = form.save(commit=False)
            for symbol in symbols:
                requirement.symbol = symbol
                requirement.name = list[symbol]
                requirement.save()
            data['form_is_valid'] = True
            requirements = Requirement.objects.filter()
            context = {requirement': requirement, 'requirements': requirements}
            data['html_requirement'] = render_to_string('project/requirement_list.html', context)
        else:
            data['form_is_valid'] = False
    else:
        form = RequirementAddForm()
    context = {'form': form}
    data['html_requirement_form'] = render_to_string('project/requirement_add.html', context, request=request)
    return JsonResponse(data)

Answer 1

You can manipulate your form at it's initialization:

REQUIREMENTS_CHOICES = (
        ('A', 'Name A'),
        ('B', 'Name B'),
        ('C', 'Name C'),
        ('D', 'Name D'),
)


class RequirementAddForm(forms.ModelForm):
    def __init__(self, symbols='', *args, **kwargs):
        super(RequirementAddForm, self).__init__(*args, **kwargs)

        UPDATED_CHOICES = () # empty tuple
        for choice in REQUIREMENTS_CHOICES:
            if choice[1] not in symbols:
                UPDATED_CHOICES += (choice,) # adds choice as a tuple

        self.fields['symbol'] = forms.MultipleChoiceField(
                                    required=False,
                                    widget=forms.CheckboxSelectMultiple, 
                                    choices=UPDATED_CHOICES,
                                )

    class Meta:
        model = Requirement

What happens above:

1. When you initialize your form
   (ex: form=RequirementAddForm(symbols=existing_symbols)), you can pass to the constructor, a string with the existing symbols for an item in your database.
2. The __init__ function checks which choices exist already in symbols and updates the UPDATED_CHOICES accordingly.
3. A field named symbol gets added to the form from the constructor, which have as choices the UPDATED_CHOICES.