Django multiple checkbox form with raw quesyset

I have two model:

class items(models.Model):
    type = models.CharField()
    model = models.CharField()

class cart(models.Model):
    client = models.ForeignKey(client, on_delete=models.CASCADE)
    type = models.CharField()

What I want to do is to create a form that show all the items' type not already into the cart for a client. I need a multiple checkbox (and possibly an header checkbox for "select all")

I made this form manually but there is a way to make it using django form?

I tried with this code but I'm not sure that this is the best solution. How can I add a "select all" checkbox?

form.py

class AddItemsForm(Form):
    def __init__(self, *args, **kwargs):
        self.client_id = kwargs.pop('client_id')
        super(AddItemsForm, self).__init__(*args, **kwargs)
        pl = items.objects.raw("SELECT * FROM app_items WHERE type NOT IN (SELECT type FROM app_cart WHERE client_id = %s)" % self.client_id)
        b = []
        for p in pl:
            b.append([p.type, p.type])

        self.fields["choices"] = MultipleChoiceField(
            choices = b,
            widget  = CheckboxSelectMultiple,
        )
        self.fields['choices'].label = ''

view.py:

def pricelist_addcountries_form(request, client_id):  
    if request.method == 'POST':
    form = AddItemsForm(request.POST)
    if form.is_valid():
        ...
        return redirect(reverse('app:index'))
    else:
        form = AddItemsForm(client_id=client_id)

    return render(request, 'app/form.html', {'form': form})

thanks in advance!