#27001: Regression in query counts using RadioSelect with ModelChoiceField
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Reporter: AlexHill | Owner: nobody
Type: Uncategorized | Status: new
Component: Forms | Version: 1.10
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by AlexHill):
Created a pull request with a fix.
`ChoiceFieldRenderer` doesn't have `__iter__` defined, so Python iterates
over it by calling `__getitem__` with an increasing index until an
exception is raised. `ChoiceFieldRenderer.__getitem__` calls `list` on
itself, which turns iteration into an n^2 operation. When the choices are
backed by a queryset as in ModelChoiceField, that means lots of redundant
database queries.
Fixed by adding an `__iter__` method to `ChoiceFieldRenderer` and changing
`__getitem__` to use it, so that indexing still works.
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Ticket URL: <https://code.djangoproject.com/ticket/27001#comment:3>
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