Django admin inlines for unrelated models

This app allows you to create admin inlines for models that don't have an explicit foreign key relationship.

To use, subclass your inline from NonrelatedStackedInline and add get_form_queryset and save_new_instance methods.

• get_form_queryset(self, obj) returns all objects that should be shown in the inline formset.
• save_new_instance(self, parent, instance) given a parent object and a new child object instance should associate the child object with the parent.

For example, let's assume we have Customer and Invoice models. Invoice objects are associated with a Customer if they share the same email address.

from nonrelated_inlines.admin import NonrelatedStackedInline


class CustomerInvoiceStackedInline(NonrelatedStackedInline):
    model = Invoice
    fields = [
        'id',
        'amount'
    ]

    def get_form_queryset(self, obj):
        return self.model.objects.filter(email=obj.email)

    def save_new_instance(self, parent, instance):
        instance.email = parent.email

When viewing an Customer instance, we fetch a queryset of all Invoice instances sharing the same email address. Similarly, when saving a new Invoice instance we make sure to set its email attribute to the same value as its parent Customer.