better document overridden model save not called on bulk update.

[bram.dejong@…]

The documentation on overriding predefined model methods should mention that bulk updates do no trigger customized save methods. I.e. if I do MyModel.objects.all().update(a=5) will not trigger MyModel.save().

The docs do already mention this in the description of update( ) but not in the description of overriding methods:
​https://docs.djangoproject.com/en/dev/topics/db/models/#overriding-predefined-model-methods

[Tomáš Ehrlich]

Improved documentation

[Anssi Kääriäinen]

The patch isn't correct - you can't use pre/post_save for update operations. In addition, bulk_create would be good to mention at the same time, too. It is a bit sad that there isn't anything you can use for .update() operations currently...

[Tomáš Ehrlich]

save(), pre_save and post_save are not called

[Tim Graham]

Minor tweaks to last patch

[Tomáš Ehrlich]

Thanks, it's there ​https://github.com/django/django/pull/422

[Tomáš Ehrlich <tomas.ehrlich@…>]

In 443999a1eeea70e4deebcf31f8f845696be62c3d:

Fixed #18996 - Docs on overriden model methods

[Tim Graham <timograham@…>]

In 5fb22329a14695419f191da8b7d0b5b22793aff0:

Merge pull request #422 from elvard/18996

Fixed #18996 - Clarified overriden model methods not called on bulk operations

[Tim Graham <timograham@…>]

In d2891d1c0751d53c10f19672ac7d232b6e5088b0:

[1.4.x] Fixed #18996 - Clarified overriden model methods not called on bulk operations

Backport of 443999a1eeea70e4deebcf31f8f845696be62c3d from master.