Commit d579e716 authored by Malcolm Tredinnick's avatar Malcolm Tredinnick
Browse files

Fixed #9997 -- Fixed use of ValuesQuerySets as rvalues in filters. 

Previous behaviour was pretty stupid. Let's never speak of it again. New
behaviour both works and is documented.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9759 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent 14b3f030

django/db/models/query.py

+14 −0
Original line number Diff line number Diff line
@@ -798,6 +798,20 @@ class ValuesQuerySet(QuerySet): 


        super(ValuesQuerySet, self)._setup_aggregate_query()



    def as_sql(self):

        """

        For ValueQuerySet (and subclasses like ValuesListQuerySet), they can

        only be used as nested queries if they're already set up to select only

        a single field (in which case, that is the field column that is

        returned). This differs from QuerySet.as_sql(), where the column to

        select is set up by Django.

        """

        if ((self._fields and len(self._fields) > 1) or

                (not self._fields and len(self.model._meta.fields) > 1)):

            raise TypeError('Cannot use a multi-field %s as a filter value.'

                    % self.__class__.__name__)

        return self._clone().query.as_nested_sql()



class ValuesListQuerySet(ValuesQuerySet):

    def iterator(self):

        self.query.trim_extra_select(self.extra_names)

docs/ref/models/querysets.txt

+16 −0
Original line number Diff line number Diff line
@@ -1136,6 +1136,7 @@ The above code fragment could also be written as follows:: 
    inner_q = Blog.objects.filter(name__contains='Cheddar').values('pk').query

    entries = Entry.objects.filter(blog__in=inner_q)





.. versionchanged:: 1.1

    In Django 1.0, only the latter piece of code is valid.
@@ -1144,6 +1145,21 @@ accesses the internal ``query`` attribute and requires a ``ValuesQuerySet``. 
If your code doesn't require compatibility with Django 1.0, use the first

form, passing in a queryset directly.



If you pass in a ``ValuesQuerySet`` or ``ValuesListQuerySet`` (the result of

calling ``values()`` or ``values_list()`` on a queryset) as the value to an

``__in`` lookup, you need to ensure you are only extracting one field in the

result. For example, this will work (filtering on the blog names)::



    inner_qs = Blog.objects.filter(name__contains='Ch').values('name')

    entries = Entry.objects.filter(blog__name__in=inner_qs)



This example will raise an exception, since the inner query is trying to

extract two field values, where only one is expected::



    # Bad code! Will raise a TypeError.

    inner_qs = Blog.objects.filter(name__contains='Ch').values('name', 'id')

    entries = Entry.objects.filter(blog__name__in=inner_qs)



.. warning::



    This ``query`` attribute should be considered an opaque internal attribute.

tests/regressiontests/queries/models.py

+16 −0
Original line number Diff line number Diff line
@@ -1022,6 +1022,22 @@ nothing). 
>>> print Annotation.objects.filter(notes__in=Note.objects.filter(note="xyzzy")).query

SELECT ...



Bug #9997 -- If a ValuesList or Values queryset is passed as an inner query, we

make sure it's only requesting a single value and use that as the thing to

select.

>>> Tag.objects.filter(name__in=Tag.objects.filter(parent=t1).values('name'))

[<Tag: t2>, <Tag: t3>]



# Multi-valued values() and values_list() querysets should raise errors.

>>> Tag.objects.filter(name__in=Tag.objects.filter(parent=t1).values('name', 'id'))

Traceback (most recent call last):

...

TypeError: Cannot use a multi-field ValuesQuerySet as a filter value.

>>> Tag.objects.filter(name__in=Tag.objects.filter(parent=t1).values_list('name', 'id'))

Traceback (most recent call last):

...

TypeError: Cannot use a multi-field ValuesListQuerySet as a filter value.



Bug #9985 -- qs.values_list(...).values(...) combinations should work.

>>> Note.objects.values_list("note", flat=True).values("id").order_by("id")

[{'id': 1}, {'id': 2}, {'id': 3}]