Naming Options (when empty field)

Hello everyone,

I’m having trouble with the naming options in one of my doctype. It is a doctype with an object in it(object = a house of a customer). I would like to have it a name in the naming options like:

format:{address} {number} {number_additive} {city}

The problem is with the {number_additive}, this is a field that can be empty and thus sometimes it results in something like this:

blablastreet 2 number_additive Amsterdam

instead of

blablastreet 2 Amsterdam

Ca anyone please help me solve this?

Thanks in advance,