#22349: RawQuerySet doesn't implement __len__, __bool__
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Reporter: cdestigter | Owner:
Type: Bug | Status: new
Component: Database layer | Version: master
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by loic84):
Dunno if it's by design, but `RawQuerySet` and `QuerySet` operate vastly
differently as there is no such thing as an "evaluated" `RawQuerySet`:
{{{
list(queryset)
with assertNumQueries(1)
for i in range(10):
queryset[0]
list(raw_queryset)
with assertNumQueries(10)
for i in range(10):
raw_queryset[0]
}}}
This fundamental difference makes having a shared ancestor impractical.
With that in mind, I think adding `__len__` would be a nasty footgun, if
you only want the number of rows, you can write a `COUNT` SQL query, if
you want the count and the result, then you should definitely store the
result in a list to avoid a second query.
Of course we could make `RawQuerySet` maintain an internal cache akin to
`QuerySet`, but that'd have to be a ticket in its own right.
--
Ticket URL: <https://code.djangoproject.com/ticket/22349#comment:4>
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