Opened 15 years ago

Closed 11 years ago

#10657 closed Bug (fixed)

Meta option 'ordering' causes problems with nullable fields

Reported by: andrewl Owned by: nobody
Component: Database layer (models, ORM) Version: 1.0
Severity: Normal Keywords: ordering, order_by
Cc: Triage Stage: Design decision needed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no


See also ticket:10574 which basically seems to be talking about the same thing under a slightly different setup.

Specifying fields which may be null in the Meta option 'ordering' causes problems later on when retrieving model records.

See the attached Model definition and fixture for an example. Note that the Model definition appears to require one 'level' of inheritance for the problem to occur (hence the Animal-Person/Pet relationship) - the model and fixture files with the suffix 'safe' demonstrate a similar setup which does not suffer from the problem.

To reproduce the problem, set up the example application with the fixture, and try House.objects.all().count(), which will return the correct count of 2. However House.objects.all() will return only 1 House - the missing House has a null record for the 'pet' field. House.objects.all().order_by() returns both Houses.

The problem should either be fixed or (as I recognise that the underlying problem is a tad complex) the Model Meta options documentation on the 'ordering' option should include a note to the effect that 'Ordering by nullable fields, though legal, is unpredictable'.

Attachments (1) (1.4 KB) - added by andrewl 15 years ago.
Sample Model and Initial Data

Download all attachments as: .zip

Change History (7)

Changed 15 years ago by andrewl

Attachment: added

Sample Model and Initial Data

comment:1 Changed 15 years ago by Jacob

Triage Stage: UnreviewedDesign decision needed

comment:2 Changed 13 years ago by Julien Phalip

Component: Core frameworkDatabase layer (models, ORM)

comment:3 Changed 13 years ago by Seth Buntin

Severity: Normal
Type: Bug

comment:4 Changed 12 years ago by Aymeric Augustin

UI/UX: unset

Change UI/UX from NULL to False.

comment:5 Changed 12 years ago by Aymeric Augustin

Easy pickings: unset

Change Easy pickings from NULL to False.

comment:6 Changed 11 years ago by Anssi Kääriäinen

Resolution: fixed
Status: newclosed

This has been fixed a long time ago.

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