Django admin foreign key drop down field list only "test object"

I have these two classes:

class Test(models.Model):
    id = models.AutoField(primary_key=True)
    user = models.ForeignKey(User)
    groups = models.ManyToManyField(Group)

class TestSubjectSet(models.Model):
    id =  models.AutoField(primary_key=True)
    test = models.ForeignKey(Test)
    subject = models.ManyToManyField(Subject)

The TestSubjectSet form test list shows only string "test object".

Can a Django model have 2 foreign keys?

First of all, anything is possible. Models can have multiple foreign keys.

How does Django foreign key work?

Introduction to Django Foreign Key. A foreign key is a process through which the fields of one table can be used in another table flexibly. So, two different tables can be easily linked by means of the foreign key. This linking of the two tables can be easily achieved by means of foreign key processes.

You have to add __unicode__(self) or __str__(self) methods in your models class.

http://docs.djangoproject.com/en/dev/ref/models/instances/?from=olddocs#django.db.models.Model.unicode