Fixed #10182 -- Corrected realiasing and the process of evaluating values() for queries with aggregate clauses. This means that aggregate queries can now be used as subqueries (such as in an __in clause). Thanks to omat for the report.

This involves a slight change to the interaction of annotate() and values() clauses that specify a list of columns. See the docs for details.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9888 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/aggregates.py

@@ -46,7 +46,7 @@ class Aggregate(object):
         # Validate that the backend has a fully supported, correct
         # implementation of this aggregate
         query.connection.ops.check_aggregate_support(aggregate)
-        query.aggregate_select[alias] = aggregate
+        query.aggregates[alias] = aggregate
 
 class Avg(Aggregate):
     name = 'Avg'

django/db/models/query.py

@@ -596,7 +596,7 @@ class QuerySet(object):
 
         obj = self._clone()
 
-        obj._setup_aggregate_query()
+        obj._setup_aggregate_query(kwargs.keys())
 
         # Add the aggregates to the query
         for (alias, aggregate_expr) in kwargs.items():
@@ -693,7 +693,7 @@ class QuerySet(object):
         """
         pass
 
-    def _setup_aggregate_query(self):
+    def _setup_aggregate_query(self, aggregates):
         """
         Prepare the query for computing a result that contains aggregate annotations.
         """
@@ -773,6 +773,8 @@ class ValuesQuerySet(QuerySet):
 
         self.query.select = []
         self.query.add_fields(self.field_names, False)
+        if self.aggregate_names is not None:
+            self.query.set_aggregate_mask(self.aggregate_names)
 
     def _clone(self, klass=None, setup=False, **kwargs):
         """
@@ -798,13 +800,17 @@ class ValuesQuerySet(QuerySet):
             raise TypeError("Merging '%s' classes must involve the same values in each case."
                     % self.__class__.__name__)
 
-    def _setup_aggregate_query(self):
+    def _setup_aggregate_query(self, aggregates):
         """
         Prepare the query for computing a result that contains aggregate annotations.
         """
         self.query.set_group_by()
 
-        super(ValuesQuerySet, self)._setup_aggregate_query()
+        if self.aggregate_names is not None:
+            self.aggregate_names.extend(aggregates)
+            self.query.set_aggregate_mask(self.aggregate_names)
+
+        super(ValuesQuerySet, self)._setup_aggregate_query(aggregates)
 
     def as_sql(self):
         """
@@ -824,6 +830,7 @@ class ValuesListQuerySet(ValuesQuerySet):
     def iterator(self):
         if self.extra_names is not None:
             self.query.trim_extra_select(self.extra_names)
+
         if self.flat and len(self._fields) == 1:
             for row in self.query.results_iter():
                 yield row[0]
@@ -837,6 +844,7 @@ class ValuesListQuerySet(ValuesQuerySet):
             extra_names = self.query.extra_select.keys()
             field_names = self.field_names
             aggregate_names = self.query.aggregate_select.keys()
+
             names = extra_names + field_names + aggregate_names
 
             # If a field list has been specified, use it. Otherwise, use the

django/db/models/sql/query.py

@@ -77,7 +77,9 @@ class BaseQuery(object):
         self.related_select_cols = []
 
         # SQL aggregate-related attributes
-        self.aggregate_select = SortedDict() # Maps alias -> SQL aggregate function
+        self.aggregates = SortedDict() # Maps alias -> SQL aggregate function
+        self.aggregate_select_mask = None
+        self._aggregate_select_cache = None
 
         # Arbitrary maximum limit for select_related. Prevents infinite
         # recursion. Can be changed by the depth parameter to select_related().
@@ -187,7 +189,15 @@ class BaseQuery(object):
         obj.distinct = self.distinct
         obj.select_related = self.select_related
         obj.related_select_cols = []
-        obj.aggregate_select = self.aggregate_select.copy()
+        obj.aggregates = self.aggregates.copy()
+        if self.aggregate_select_mask is None:
+            obj.aggregate_select_mask = None
+        else:
+            obj.aggregate_select_mask = self.aggregate_select_mask[:]
+        if self._aggregate_select_cache is None:
+            obj._aggregate_select_cache = None
+        else:
+            obj._aggregate_select_cache = self._aggregate_select_cache.copy()
         obj.max_depth = self.max_depth
         obj.extra_select = self.extra_select.copy()
         obj.extra_tables = self.extra_tables
@@ -940,14 +950,17 @@ class BaseQuery(object):
         """
         assert set(change_map.keys()).intersection(set(change_map.values())) == set()
 
-        # 1. Update references in "select" and "where".
+        # 1. Update references in "select" (normal columns plus aliases),
+        # "group by", "where" and "having".
         self.where.relabel_aliases(change_map)
-        for pos, col in enumerate(self.select):
-            if isinstance(col, (list, tuple)):
-                old_alias = col[0]
-                self.select[pos] = (change_map.get(old_alias, old_alias), col[1])
-            else:
-                col.relabel_aliases(change_map)
+        self.having.relabel_aliases(change_map)
+        for columns in (self.select, self.aggregates.values(), self.group_by or []):
+            for pos, col in enumerate(columns):
+                if isinstance(col, (list, tuple)):
+                    old_alias = col[0]
+                    columns[pos] = (change_map.get(old_alias, old_alias), col[1])
+                else:
+                    col.relabel_aliases(change_map)
 
         # 2. Rename the alias in the internal table/alias datastructures.
         for old_alias, new_alias in change_map.iteritems():
@@ -1205,11 +1218,11 @@ class BaseQuery(object):
         opts = model._meta
         field_list = aggregate.lookup.split(LOOKUP_SEP)
         if (len(field_list) == 1 and
-            aggregate.lookup in self.aggregate_select.keys()):
+            aggregate.lookup in self.aggregates.keys()):
             # Aggregate is over an annotation
             field_name = field_list[0]
             col = field_name
-            source = self.aggregate_select[field_name]
+            source = self.aggregates[field_name]
         elif (len(field_list) > 1 or
             field_list[0] not in [i.name for i in opts.fields]):
             field, source, opts, join_list, last, _ = self.setup_joins(
@@ -1299,7 +1312,7 @@ class BaseQuery(object):
             value = SQLEvaluator(value, self)
             having_clause = value.contains_aggregate
 
-        for alias, aggregate in self.aggregate_select.items():
+        for alias, aggregate in self.aggregates.items():
             if alias == parts[0]:
                 entry = self.where_class()
                 entry.add((aggregate, lookup_type, value), AND)
@@ -1824,8 +1837,8 @@ class BaseQuery(object):
         self.group_by = []
         if self.connection.features.allows_group_by_pk:
             if len(self.select) == len(self.model._meta.fields):
-                self.group_by.append('.'.join([self.model._meta.db_table,
-                                               self.model._meta.pk.column]))
+                self.group_by.append((self.model._meta.db_table,
+                                      self.model._meta.pk.column))
                 return
 
         for sel in self.select:
@@ -1858,7 +1871,11 @@ class BaseQuery(object):
             # Distinct handling is done in Count(), so don't do it at this
             # level.
             self.distinct = False
-        self.aggregate_select = {None: count}
+
+        # Set only aggregate to be the count column.
+        # Clear out the select cache to reflect the new unmasked aggregates.
+        self.aggregates = {None: count}
+        self.set_aggregate_mask(None)
 
     def add_select_related(self, fields):
         """
@@ -1920,6 +1937,29 @@ class BaseQuery(object):
         for key in set(self.extra_select).difference(set(names)):
             del self.extra_select[key]
 
+    def set_aggregate_mask(self, names):
+        "Set the mask of aggregates that will actually be returned by the SELECT"
+        self.aggregate_select_mask = names
+        self._aggregate_select_cache = None
+
+    def _aggregate_select(self):
+        """The SortedDict of aggregate columns that are not masked, and should
+        be used in the SELECT clause.
+
+        This result is cached for optimization purposes.
+        """
+        if self._aggregate_select_cache is not None:
+            return self._aggregate_select_cache
+        elif self.aggregate_select_mask is not None:
+            self._aggregate_select_cache = SortedDict([
+                (k,v) for k,v in self.aggregates.items()
+                if k in self.aggregate_select_mask
+            ])
+            return self._aggregate_select_cache
+        else:
+            return self.aggregates
+    aggregate_select = property(_aggregate_select)
+
     def set_start(self, start):
         """
         Sets the table from which to start joining. The start position is

django/db/models/sql/where.py

@@ -213,10 +213,14 @@ class WhereNode(tree.Node):
             elif isinstance(child, tree.Node):
                 self.relabel_aliases(change_map, child)
             else:
-                elt = list(child[0])
-                if elt[0] in change_map:
-                    elt[0] = change_map[elt[0]]
-                    node.children[pos] = (tuple(elt),) + child[1:]
+                if isinstance(child[0], (list, tuple)):
+                    elt = list(child[0])
+                    if elt[0] in change_map:
+                        elt[0] = change_map[elt[0]]
+                        node.children[pos] = (tuple(elt),) + child[1:]
+                else:
+                    child[0].relabel_aliases(change_map)
+
                 # Check if the query value also requires relabelling
                 if hasattr(child[3], 'relabel_aliases'):
                     child[3].relabel_aliases(change_map)

docs/topics/db/aggregation.txt

@@ -284,9 +284,6 @@ two authors with the same name, their results will be merged into a single
 result in the output of the query; the average will be computed as the
 average over the books written by both authors.
 
-The annotation name will be added to the fields returned
-as part of the ``ValuesQuerySet``.
-
 Order of ``annotate()`` and ``values()`` clauses
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -303,12 +300,21 @@ output.
 For example, if we reverse the order of the ``values()`` and ``annotate()``
 clause from our previous example::
 
-    >>> Author.objects.annotate(average_rating=Avg('book__rating')).values('name')
+    >>> Author.objects.annotate(average_rating=Avg('book__rating')).values('name', 'average_rating')
 
 This will now yield one unique result for each author; however, only
 the author's name and the ``average_rating`` annotation will be returned
 in the output data.
 
+You should also note that ``average_rating`` has been explicitly included
+in the list of values to be returned. This is required because of the
+ordering of the ``values()`` and ``annotate()`` clause.
+
+If the ``values()`` clause precedes the ``annotate()`` clause, any annotations
+will be automatically added to the result set. However, if the ``values()``
+clause is applied after the ``annotate()`` clause, you need to explicitly
+include the aggregate column.
+
 Aggregating annotations
 -----------------------
 

tests/modeltests/aggregation/models.py

@@ -207,10 +207,9 @@ u'The Definitive Guide to Django: Web Development Done Right'
 >>> Book.objects.filter(pk=1).annotate(mean_age=Avg('authors__age')).values('pk', 'isbn', 'mean_age')
 [{'pk': 1, 'isbn': u'159059725', 'mean_age': 34.5}]
 
-# Calling it with paramters reduces the output but does not remove the
-# annotation.
+# Calling values() with parameters reduces the output
 >>> Book.objects.filter(pk=1).annotate(mean_age=Avg('authors__age')).values('name')
-[{'name': u'The Definitive Guide to Django: Web Development Done Right', 'mean_age': 34.5}]
+[{'name': u'The Definitive Guide to Django: Web Development Done Right'}]
 
 # An empty values() call before annotating has the same effect as an
 # empty values() call after annotating

tests/regressiontests/aggregation_regress/models.py

@@ -95,10 +95,18 @@ __test__ = {'API_TESTS': """
 >>> sorted(Book.objects.all().values().annotate(mean_auth_age=Avg('authors__age')).extra(select={'manufacture_cost' : 'price * .5'}).get(pk=2).items())
 [('contact_id', 3), ('id', 2), ('isbn', u'067232959'), ('manufacture_cost', ...11.545...), ('mean_auth_age', 45.0), ('name', u'Sams Teach Yourself Django in 24 Hours'), ('pages', 528), ('price', Decimal("23.09")), ('pubdate', datetime.date(2008, 3, 3)), ('publisher_id', 2), ('rating', 3.0)]
 
-# A values query that selects specific columns reduces the output
+# If the annotation precedes the values clause, it won't be included
+# unless it is explicitly named
 >>> sorted(Book.objects.all().annotate(mean_auth_age=Avg('authors__age')).extra(select={'price_per_page' : 'price / pages'}).values('name').get(pk=1).items())
+[('name', u'The Definitive Guide to Django: Web Development Done Right')]
+
+>>> sorted(Book.objects.all().annotate(mean_auth_age=Avg('authors__age')).extra(select={'price_per_page' : 'price / pages'}).values('name','mean_auth_age').get(pk=1).items())
 [('mean_auth_age', 34.5), ('name', u'The Definitive Guide to Django: Web Development Done Right')]
 
+# If an annotation isn't included in the values, it can still be used in a filter
+>>> Book.objects.annotate(n_authors=Count('authors')).values('name').filter(n_authors__gt=2)
+[{'name': u'Python Web Development with Django'}]
+
 # The annotations are added to values output if values() precedes annotate()
 >>> sorted(Book.objects.all().values('name').annotate(mean_auth_age=Avg('authors__age')).extra(select={'price_per_page' : 'price / pages'}).get(pk=1).items())
 [('mean_auth_age', 34.5), ('name', u'The Definitive Guide to Django: Web Development Done Right')]
@@ -207,6 +215,11 @@ FieldError: Cannot resolve keyword 'foo' into field. Choices are: authors, conta
 >>> Book.objects.extra(select={'pub':'publisher_id','foo':'pages'}).values('pub').annotate(Count('id')).order_by('pub')
 [{'pub': 1, 'id__count': 2}, {'pub': 2, 'id__count': 1}, {'pub': 3, 'id__count': 2}, {'pub': 4, 'id__count': 1}]
 
+# Regression for #10182 - Queries with aggregate calls are correctly realiased when used in a subquery
+>>> ids = Book.objects.filter(pages__gt=100).annotate(n_authors=Count('authors')).filter(n_authors__gt=2).order_by('n_authors')
+>>> Book.objects.filter(id__in=ids)
+[<Book: Python Web Development with Django>]
+
 # Regression for #10199 - Aggregate calls clone the original query so the original query can still be used
 >>> books = Book.objects.all()
 >>> _ = books.aggregate(Avg('authors__age'))