ManyRelatedManager.add() does not accept `bulk` kwarg as described in documentation

[Brenton Partridge]

​https://docs.djangoproject.com/en/2.0/ref/models/relations/#django.db.models.fields.related.RelatedManager.add suggests that RelatedManager.add(*objs, bulk=True) accepts the bulk kwarg regardless of the type of relationship. However, for many-to-many relationships, ​https://github.com/django/django/blob/2919a08c20d5ae48e381d6bd251d3b0d400d47d9/django/db/models/fields/related_descriptors.py#L909 does not accept any kwargs. (Master branch as of the submission of this ticket.)

This leads to errors like add() got an unexpected keyword argument ‘bulk’.

This could be fixed in documentation, since for many-to-many the inserts are going to be bulk regardless. But then RelatedManager wouldn't have a consistent interface across all types of relations. Alternately, we could just add the kwarg to the code and ignore it, and document more clearly that "all many-to-many adds are inserted in bulk, regardless of the choice of bulk kwarg." But we shouldn't just error out on a developer who attempts to follow the documentation.

Any thoughts?

[Tim Graham]

Duplicate of #29255. A sentence was recently added to the documentation that states that the bulk argument doesn't exist for many to many relations.