admin.ModelAdmin.formfield_for_foreignkey()

ModelAdmin.formfield_for_foreignkey(db_field, request, **kwargs)

The formfield_for_foreignkey method on a ModelAdmin allows you to override the default formfield for a foreign keys field. For example, to return a subset of objects for this foreign key field based on the user:

class MyModelAdmin(admin.ModelAdmin):
    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if db_field.name == "car":
            kwargs["queryset"] = Car.objects.filter(owner=request.user)
        return super(MyModelAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)

This uses the HttpRequest instance to filter the Car foreign key field to only display the cars owned by the User instance.