is_registered_user is a method of Subject, not a field, thus it can't be used for filtering.
In the admin of a Django model, filter fields must be database fields, or some extra work is needed using BooleanFieldListFilter or SimpleListFilter from django.contrib.admin.filters.
is_registered_useris a method ofSubject, not a field, thus it can't be used for filtering.In the admin of a Django model, filter fields must be database fields, or some extra work is needed using
BooleanFieldListFilterorSimpleListFilterfromdjango.contrib.admin.filters.