  # Nullable ForeignKey
  class NullableForeignKeySource(RESTFrameworkModel):
      name = models.CharField(max_length=100)
      target = models.ForeignKey(ForeignKeyTarget, null=True, blank=True,
                                 related_name='nullable_sources')
  
  
  # OneToOne
  class OneToOneTarget(RESTFrameworkModel):
      name = models.CharField(max_length=100)
 
</s> remove     target = models.ForeignKey(ForeignKeyTarget, related_name='sources')
 </s> add     target = models.ForeignKey(ForeignKeyTarget, related_name='sources',
                               verbose_name='Target object')
                               related_name='nullable_sources',
                               verbose_name='Optional target object')
  # Nullable ForeignKey
  class NullableForeignKeySource(RESTFrameworkModel):
      name = models.CharField(max_length=100)
      target = models.ForeignKey(ForeignKeyTarget, null=True, blank=True,
                               related_name='nullable_sources',
                               verbose_name='Optional target object')
  
  
  # OneToOne
  class OneToOneTarget(RESTFrameworkModel):
      name = models.CharField(max_length=100)
keep keep keep keep replace keep keep keep keep keep
 Metadata for related fields -- added test case. 
rest_framework/tests/models.py