#28284: Paginator._check_object_list_is_ordered should not call __repr__ on
self.object_list
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Reporter: Tom | Owner: nobody
Type: Uncategorized | Status: new
Component: Core (Other) | Version: 1.11
Severity: Normal | 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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The `_check_object_list_is_ordered` function in Paginator currently throws
a warning if the queryset is unordered. As part of this warning the
queryset is formatted using `{!r}`, which ends up calling the `__repr__`
or `__str__` of each of the items in the QuerySet.
This causes the entire queryset to be evaluated and all rows fetched, and
if `__repr__` uses any foreign keys these are also fetched, resulting in a
lot of queries. Warnings are also silent by default, and the string is
*always* evaluated regardless of if the warning is displayed or not.
Also, the warning is conditional: Pagination *may* yield inconsistent
results. Some databases may vary, so to people who use these backends this
change just introduced something that evaluates the entire queryset every
time the Paginator is used for no particular reason.
I propose that the warning is either replaced by a hard error, or the
warning is changed to perhaps display the model name of the queryset, or
some other information that doesn't require iterating the queryset.
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Ticket URL: <https://code.djangoproject.com/ticket/28284>
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