Django GenericForeignKey: accessor clash when 2 models have same related_name

Question

When I syncdb, I get many errors like this:

   transcription.transcription1: Accessor for field 'participant_content_type' clashes with related field 'ContentType.auxi
    liary_model_as_participant'. Add a related_name argument to the definition for 'participant_content_type'.
    transcription.transcription1: Reverse query name for field 'participant_content_type' clashes with related field 'Conten
    tType.auxiliary_model_as_participant'. Add a related_name argument to the definition for 'participant_content_type'.

My models already have related names:

# my base class which I intend to inherit from in many places.
# Many types of AuxiliaryModel will point at participant/match objects.:
class AuxiliaryModel(models.Model):
    participant_content_type = models.ForeignKey(ContentType,
                                                 editable=False,
                                                 related_name = 'auxiliary_model_as_participant')
    participant_object_id = models.PositiveIntegerField(editable=False)
    participant = generic.GenericForeignKey('participant_content_type',
                                            'participant_object_id',
                                            )

    match_content_type = models.ForeignKey(ContentType,
                                           editable=False,
                                           related_name = 'auxiliary_model_as_match')
    match_object_id = models.PositiveIntegerField(editable=False)
    match = generic.GenericForeignKey('match_content_type',
                                      'match_object_id',
                                      )

    class Meta:
        abstract = True


class Transcription(AuxiliaryModel):

    transcription = models.TextField(max_length=TRANSCRIPTION_MAX_LENGTH,
                                        null=True)

    class Meta:
        abstract = True

class Transcription1(Transcription):
    pass

class Transcription2(Transcription):
    pass

class Transcription3(Transcription):
    pass

The problem goes away when I comment out Transcription2 and Transcription3, so it seems like the related_names clash. Do I have to make them unique? If so, is there a way to do this without having to write boilerplate code in each child class?

Answer 1

From the Django docs https://docs.djangoproject.com/en/dev/topics/db/models/#be-careful-with-related-name :

If you are using the related_name attribute on a ForeignKey or ManyToManyField, you must always specify a unique reverse name for the field. This would normally cause a problem in abstract base classes, since the fields on this class are included into each of the child classes, with exactly the same values for the attributes (including related_name) each time.

To work around this problem, when you are using related_name in an abstract base class (only), part of the name should contain '%(app_label)s' and '%(class)s'.

In this case, I think this will work:

    participant_content_type = models.ForeignKey(ContentType,
                                             editable=False,
                                             related_name = '%(app_label)s_%(class)s_as_participant')
    match_content_type = models.ForeignKey(ContentType,
                                       editable=False,
                                       related_name = '%(app_label)s_%(class)s_model_as_match')

So, using %(app_label)_transcription2_as_participant you can access the reverse of Transcription2.participant_content_type