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| author | Moayad Mardini <moayad.m@gmail.com> | 2014-06-12 20:43:30 +0300 |
|---|---|---|
| committer | Tim Graham <timograham@gmail.com> | 2014-06-12 16:41:49 -0400 |
| commit | 2d425116e2f26ab546c380784df1de79562009a7 (patch) | |
| tree | adf706ec5cab2725fbcd15999c2a993c096aaca9 | |
| parent | 386166970c506b5f7b70f63bfb86d1ea64a980cf (diff) | |
Fixed #22349 -- Added a note clarifying `RawQuerySet` has no `__len__`.
Thanks cdestigter for the report.
| -rw-r--r-- | AUTHORS | 1 | ||||
| -rw-r--r-- | docs/topics/db/sql.txt | 14 |
2 files changed, 14 insertions, 1 deletions
@@ -422,6 +422,7 @@ answer newbie questions, and generally made Django that much better: Javier Mansilla <javimansilla@gmail.com> masonsimon+django@gmail.com Manuzhai + Moayad Mardini <moayad.m@gmail.com> Petr Marhoun <petr.marhoun@gmail.com> Petar Marić <http://www.petarmaric.com/> Nuno Mariz <nmariz@gmail.com> diff --git a/docs/topics/db/sql.txt b/docs/topics/db/sql.txt index 4a1b361f11..131e1d50db 100644 --- a/docs/topics/db/sql.txt +++ b/docs/topics/db/sql.txt @@ -33,7 +33,8 @@ return model instances: This method takes a raw SQL query, executes it, and returns a ``django.db.models.query.RawQuerySet`` instance. This ``RawQuerySet`` instance -can be iterated over just like a normal QuerySet to provide object instances. +can be iterated over just like a normal +:class:`~django.db.models.query.QuerySet` to provide object instances. This is best illustrated with an example. Suppose you have the following model:: @@ -84,6 +85,17 @@ options that make it very powerful. both rows will match. To prevent this, perform the correct typecasting before using the value in a query. +.. warning:: + + While a ``RawQuerySet`` instance can be iterated over like a normal + :class:`~django.db.models.query.QuerySet`, ``RawQuerySet`` doesn't + implement all methods you can use with ``QuerySet``. For example, + ``__bool__()`` and ``__len__()`` are not defined in ``RawQuerySet``, and + thus all ``RawQuerySet`` instances are considered ``True``. The reason + these methods are not implemented in ``RawQuerySet`` is that implementing + them without internal caching would be a performance drawback and adding + such caching would be backward incompatible. + Mapping query fields to model fields ------------------------------------ |