How to access class instance from within the inline declaration?

Question

I think this is best understood with an example:

Pizzas and Toppings have a many to many relationship. I want to display a Pizza's toppings in a TabularInline.

class ToppingInlineAdmin(admin.TabularInline):
    model = Pizza.toppings.through
    fields = ('topping',)
    extra = 0
    if not model.topping.count():
        classes = ['collapse']

As you can see, I only want to collapse the tabular inline if there are no toppings on the pizza.

The code model.topping.count() does not work though. The error is:

AttributeError: 'ForwardManyToOneDescriptor' object has no attribute 'count'

Do you know how I can accomplish if no toppings on the pizza, collapse the tabular inline?

Thank you.

Iain Shelvington · Accepted Answer · 2016-11-16 17:32:53Z

1

Firstly, model should be Toppings.

class ToppingInlineAdmin(admin.TabularInline):
    model = Toppings

To conditionally set classes on your InlineModelAdmin you need to override a method that takes the object, django does not provide a method specifically for this functionality but I have overridden get_formset as an example

def get_formset(self, request, obj=None, **kwargs):
    if not obj or not obj.toppings.count():
        self.classes = ['collapse']
    return super(ToppingInlineAdmin, self).get_formset(request, obj=obj, **kwargs)

edited Nov 16, 2016 at 17:32

answered Nov 16, 2016 at 17:26

Iain Shelvington

32.5k3 gold badges36 silver badges55 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Tom Brock Over a year ago

Thank you very much for the explanation. I appreciate it.

Collectives™ on Stack Overflow

How to access class instance from within the inline declaration?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related