title: Django shows object reference in foreign key column
body: <p>I have 2 classes defined in my models.py:</p>
  
  <pre><code>class Job(models.Model):
      job_id = models.CharField(primary_key=True, max_length=10)
      job_title = models.CharField(max_length=35)
      min_salary = models.IntegerField(blank=True, null=True)
      max_salary = models.IntegerField(blank=True, null=True)
      class Meta:
          managed = False
          db_table = 'jobs'
      def __str__(self):
          return self.job_id
  
  class Employee(models.Model):
      employee_id = models.IntegerField(primary_key=True)
      first_name = models.CharField(max_length=20, blank=True)
      last_name = models.CharField(max_length=25)
      email = models.CharField(unique=True, max_length=25)
      phone_number = models.CharField(max_length=20, blank=True)
      hire_date = models.DateField()
      job = models.ForeignKey('Job')
      salary = models.DecimalField(max_digits=8, decimal_places=2, blank=True, null=True)
      commission_pct = models.DecimalField(max_digits=2, decimal_places=2, blank=True, null=True)
      manager = models.ForeignKey('self', blank=True, null=True, related_name ='employee')
      department_id = models.IntegerField(blank=True, null=True)
      class Meta:
          managed = False
          db_table = 'employees'
          def __str__(self):
             return self.employee_id
          def __unicode__(self):
             return self.employee_id
  </code></pre>
  
  <p>The issue is with foreign keys, on Employees admin page the Job field correctly displays drop-down with all possible job_ids, but the manager field displays drop-down with all entries equal "Employee object". I suspect this is because manager is a foreign key to <code>self.employee</code>.</p>
  
  <p>How do I fix that?</p>
  
  <p>Thank you.</p>