#20625: Custom Chainable QuerySets
-------------------------------------+-------------------------------------
Reporter: danols | Owner: danols
Type: New feature | Status: assigned
Component: Database layer | Version: master
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: QuerySet, | Needs documentation: 0
models.Manager, chainable | Patch needs improvement: 0
Has patch: 1 | UI/UX: 0
Needs tests: 0 |
Easy pickings: 0 |
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Changes (by lukeplant):
* stage: Unreviewed => Accepted
Comment:
I'm accepting the ticket in principle - we need a solution to this
problem, evidenced by the number of solutions/complaints out there:
https://github.com/zacharyvoase/django-qmethod
http://stackoverflow.com/questions/4576622/in-django-can-you-add-a-method-
to-querysets
http://djangosnippets.org/snippets/562/
http://djangosnippets.org/snippets/734/
http://djangosnippets.org/snippets/2114/
http://djangosnippets.org/snippets/2117/
And I don't think having multiple solutions to this problem helps people -
it just adds more-than-one-way-to-do-it.
However, I'm not at the moment accepting the approach given in the ticket
(neither am I rejecting it). We need to consider the pros/cons of the
different methods in the existing solutions above.
For the solution in the PR above, I'd say the major disadvantage is that
you have methods on the Manager which are not being used as Manager
methods, but callables that could be attached to either Managers or
!QuerySets. This means surprises w.r.t to `self` (as documented in the
example), and it would be easy to think it is working (because it works
without chaining), or to have nasty surprises if you call methods that
exist on !QuerySet but have been overridden on the Manager subclass.
--
Ticket URL: <https://code.djangoproject.com/ticket/20625#comment:4>
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