#20625: Custom Chainable QuerySets
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Reporter: danols | Owner: loic84
Type: New feature | Status: assigned
Component: Database layer | Version: master
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: QuerySet, | Needs documentation: 1
models.Manager, chainable | Patch needs improvement: 1
Has patch: 1 | UI/UX: 0
Needs tests: 1 |
Easy pickings: 0 |
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Comment (by akaariai):
I have tried various versions of making Manager a subclass of QuerySet.
The most promising approach was to use a temporary class for hiding
QuerySet only functionality from the manager, and drop the temp class on
first clone. So:
1. On creation of manager, create a dynamic class and add
HideQuerySetMethods to the `__bases__` of the dynamic class. Effect is
that for example .delete() calls HideQuerySetMethods.delete(), not
QuerySet.delete().
2. On first clone, switch the class to the original class, that is drop
the HideQuerySetMethods class from `__bases__`.
I got the solution to almost working state, but it required too many
kluges. I ended up deleting the branch as there was just too many little
problems to make it work cleanly.
I have seen the idea of this ticket discussed multiple times. Every time
some solutions are offered, but the solutions always have some problematic
cases that end up stalling the development effort. I think the solution in
this ticket is clean, and makes it easy enough to add queryset methods.
So, my opinion is that we should go forward with it.
I wouldn't actually remove the proxy methods at all. Removing them doesn't
seem worth the effort, the maintenance burden of the methods is very
small. If they are going to be removed, then all must be removed in one
go. It is just weird if some of the proxy methods are still there because
Django needs the super() method to be present, but other are removed.
It seems #17270 is a duplicate, I guess that one could be closed as this
ticket seems to have more momentum at the moment.
--
Ticket URL: <https://code.djangoproject.com/ticket/20625#comment:18>
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