Accessing parent model instance from modelform of admin inline

Question

I\'m using a TabularInline in Django\'s admin, configured to show one extra blank form.

class MyChildInline(admin.TabularInline):
    model = MyChildModel
           


        

Answer 1

Expanding on ilvar's answer a bit, If the form field of interest is constructed from a model field, you can use the following construction to apply custom behavior to it:

class MyChildInline(admin.TabularInline):
    model = MyChildModel
    extra = 1
    def get_formset(self, request, parent=None, **kwargs):
        def formfield_callback(db_field):
            """
            Constructor of the formfield given the model field.
            """
            formfield = self.formfield_for_dbfield(db_field, request=request)
            if db_field.name == 'my_choice_field' and parent is not None:
                formfield.choices = parent.get_choices()
            return formfield
        return super(MyChildInline, self).get_formset(
            request, obj=obj, formfield_callback=formfield_callback, **kwargs)
        return result