get_readonly_fields in a TabularInline class in Django?

Question

I'm trying to use get_readonly_fields in a TabularInline class in Django:

class ItemInline(admin.TabularInline):
    model = Item
    extra = 5

    def get_readonly_fields(self, request, obj=None):
        if obj:
            return ['name']

        return self.readonly_fields

This code was taken from another StackOverflow question: Django admin site: prevent fields from being edited?

However, when it's put in a TabularInline class, the new object forms don't render properly. The goal is to make certain fields read only while still allowing data to be entered in new objects. Any ideas for a workaround or different strategy?

Answer 1

Careful - "obj" is not the inline object, it's the parent. That's arguably a bug - see for example this Django ticket