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Reconciling where- and having-clause behaviour. 

Extricated the code that works directly with SQL columns (standard
"where" stuff) from the the code that takes SQL fragments and combines
it with lookup types and values. The latter portion is now more
generally reusable. Any existing code that was poking at Query.having
will now break in very visible ways (no subtle miscalculations, which is
a good thing).

This patch, en passant, removes the existing "having" test, since the
new implementation requires more setting up than previously. The
aggregates support (currently in a separate codebase) has tests for this
functionality that work as a replacement for the removed test.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9700 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2009-01-05 11:47:14 +00:00
parent ff4b844cb4
commit 062a94ef45
4 changed files with 101 additions and 77 deletions
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40
django/db/models/sql/query.py
View File

@ -16,7 +16,7 @@ from django.db import connection
from django.db.models import signals
from django.db.models.fields import FieldDoesNotExist
from django.db.models.query_utils import select_related_descend
from django.db.models.sql.where import WhereNode, EverythingNode, AND, OR
from django.db.models.sql.where import WhereNode, Constraint, EverythingNode, AND, OR
from django.db.models.sql.datastructures import Count
from django.core.exceptions import FieldError
from datastructures import EmptyResultSet, Empty, MultiJoin
@ -66,7 +66,7 @@ class BaseQuery(object):
self.where = where()
self.where_class = where
self.group_by = []
self.having = []
self.having = where()
self.order_by = []
self.low_mark, self.high_mark = 0, None # Used for offset/limit
self.distinct = False
@ -172,7 +172,7 @@ class BaseQuery(object):
obj.where = deepcopy(self.where)
obj.where_class = self.where_class
obj.group_by = self.group_by[:]
obj.having = self.having[:]
obj.having = deepcopy(self.having)
obj.order_by = self.order_by[:]
obj.low_mark, obj.high_mark = self.low_mark, self.high_mark
obj.distinct = self.distinct
@ -261,7 +261,9 @@ class BaseQuery(object):
# get_from_clause() for details.
from_, f_params = self.get_from_clause()
where, w_params = self.where.as_sql(qn=self.quote_name_unless_alias)
qn = self.quote_name_unless_alias
where, w_params = self.where.as_sql(qn=qn)
having, h_params = self.having.as_sql(qn=qn)
params = []
for val in self.extra_select.itervalues():
params.extend(val[1])
@ -291,9 +293,8 @@ class BaseQuery(object):
if not ordering:
ordering = self.connection.ops.force_no_ordering()
if self.having:
having, h_params = self.get_having()
result.append('HAVING %s' % ', '.join(having))
if having:
result.append('HAVING %s' % having)
params.extend(h_params)
if ordering:
@ -577,24 +578,6 @@ class BaseQuery(object):
result.append(str(col))
return result
def get_having(self):
"""
Returns a tuple representing the SQL elements in the "having" clause.
By default, the elements of self.having have their as_sql() method
called or are returned unchanged (if they don't have an as_sql()
method).
"""
result = []
params = []
for elt in self.having:
if hasattr(elt, 'as_sql'):
sql, params = elt.as_sql()
result.append(sql)
params.extend(params)
else:
result.append(elt)
return result, params
def get_ordering(self):
"""
Returns list representing the SQL elements in the "order by" clause.
@ -1197,7 +1180,8 @@ class BaseQuery(object):
self.promote_alias_chain(join_it, join_promote)
self.promote_alias_chain(table_it, table_promote)
self.where.add((alias, col, field, lookup_type, value), connector)
self.where.add((Constraint(alias, col, field), lookup_type, value),
connector)
if negate:
self.promote_alias_chain(join_list)
@ -1207,7 +1191,7 @@ class BaseQuery(object):
if self.alias_map[alias][JOIN_TYPE] == self.LOUTER:
j_col = self.alias_map[alias][RHS_JOIN_COL]
entry = self.where_class()
entry.add((alias, j_col, None, 'isnull', True), AND)
entry.add((Constraint(alias, j_col, None), 'isnull', True), AND)
entry.negate()
self.where.add(entry, AND)
break
@ -1216,7 +1200,7 @@ class BaseQuery(object):
# exclude the "foo__in=[]" case from this handling, because
# it's short-circuited in the Where class.
entry = self.where_class()
entry.add((alias, col, None, 'isnull', True), AND)
entry.add((Constraint(alias, col, None), 'isnull', True), AND)
entry.negate()
self.where.add(entry, AND)

15
django/db/models/sql/subqueries.py
View File

@ -6,7 +6,7 @@ from django.core.exceptions import FieldError
from django.db.models.sql.constants import *
from django.db.models.sql.datastructures import Date
from django.db.models.sql.query import Query
from django.db.models.sql.where import AND
from django.db.models.sql.where import AND, Constraint
__all__ = ['DeleteQuery', 'UpdateQuery', 'InsertQuery', 'DateQuery',
'CountQuery']
@ -48,8 +48,9 @@ class DeleteQuery(Query):
if not isinstance(related.field, generic.GenericRelation):
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
where = self.where_class()
where.add((None, related.field.m2m_reverse_name(),
related.field, 'in',
where.add((Constraint(None,
related.field.m2m_reverse_name(), related.field),
'in',
pk_list[offset : offset+GET_ITERATOR_CHUNK_SIZE]),
AND)
self.do_query(related.field.m2m_db_table(), where)
@ -59,11 +60,11 @@ class DeleteQuery(Query):
if isinstance(f, generic.GenericRelation):
from django.contrib.contenttypes.models import ContentType
field = f.rel.to._meta.get_field(f.content_type_field_name)
w1.add((None, field.column, field, 'exact',
w1.add((Constraint(None, field.column, field), 'exact',
ContentType.objects.get_for_model(cls).id), AND)
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
where = self.where_class()
where.add((None, f.m2m_column_name(), f, 'in',
where.add((Constraint(None, f.m2m_column_name(), f), 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]),
AND)
if w1:
@ -81,7 +82,7 @@ class DeleteQuery(Query):
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
where = self.where_class()
field = self.model._meta.pk
where.add((None, field.column, field, 'in',
where.add((Constraint(None, field.column, field), 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]), AND)
self.do_query(self.model._meta.db_table, where)
@ -212,7 +213,7 @@ class UpdateQuery(Query):
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
self.where = self.where_class()
f = self.model._meta.pk
self.where.add((None, f.column, f, 'in',
self.where.add((Constraint(None, f.column, f), 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]),
AND)
self.values = [(related_field.column, None, '%s')]

110
django/db/models/sql/where.py
View File

@ -13,6 +13,13 @@ from datastructures import EmptyResultSet, FullResultSet
AND = 'AND'
OR = 'OR'
class EmptyShortCircuit(Exception):
"""
Internal exception used to indicate that a "matches nothing" node should be
added to the where-clause.
"""
pass
class WhereNode(tree.Node):
"""
Used to represent the SQL where-clause.
@ -35,36 +42,35 @@ class WhereNode(tree.Node):
storing any reference to field objects). Otherwise, the 'data' is
stored unchanged and can be anything with an 'as_sql()' method.
"""
# Because of circular imports, we need to import this here.
from django.db.models.base import ObjectDoesNotExist
if not isinstance(data, (list, tuple)):
super(WhereNode, self).add(data, connector)
return
alias, col, field, lookup_type, value = data
try:
if field:
params = field.get_db_prep_lookup(lookup_type, value)
db_type = field.db_type()
else:
# This is possible when we add a comparison to NULL sometimes
# (we don't really need to waste time looking up the associated
# field object).
params = Field().get_db_prep_lookup(lookup_type, value)
db_type = None
except ObjectDoesNotExist:
# This can happen when trying to insert a reference to a null pk.
# We break out of the normal path and indicate there's nothing to
# match.
super(WhereNode, self).add(NothingNode(), connector)
return
obj, lookup_type, value = data
if hasattr(obj, "process"):
try:
obj, params = obj.process(lookup_type, value)
except EmptyShortCircuit:
# There are situations where we want to short-circuit any
# comparisons and make sure that nothing is returned. One
# example is when checking for a NULL pk value, or the
# equivalent.
super(WhereNode, self).add(NothingNode(), connector)
return
else:
params = Field().get_db_prep_lookup(lookup_type, value)
# The "annotation" parameter is used to pass auxilliary information
# about the value(s) to the query construction. Specifically, datetime
# and empty values need special handling. Other types could be used
# here in the future (using Python types is suggested for consistency).
if isinstance(value, datetime.datetime):
annotation = datetime.datetime
else:
annotation = bool(value)
super(WhereNode, self).add((alias, col, db_type, lookup_type,
annotation, params), connector)
super(WhereNode, self).add((obj, lookup_type, annotation, params),
connector)
def as_sql(self, qn=None):
"""
@ -130,12 +136,13 @@ class WhereNode(tree.Node):
Returns the string for the SQL fragment and the parameters to use for
it.
"""
table_alias, name, db_type, lookup_type, value_annot, params = child
if table_alias:
lhs = '%s.%s' % (qn(table_alias), qn(name))
lvalue, lookup_type, value_annot, params = child
if isinstance(lvalue, tuple):
# A direct database column lookup.
field_sql = self.sql_for_columns(lvalue, qn)
else:
lhs = qn(name)
field_sql = connection.ops.field_cast_sql(db_type) % lhs
# A smart object with an as_sql() method.
field_sql = lvalue.as_sql(quote_func=qn)
if value_annot is datetime.datetime:
cast_sql = connection.ops.datetime_cast_sql()
@ -175,6 +182,19 @@ class WhereNode(tree.Node):
raise TypeError('Invalid lookup_type: %r' % lookup_type)
def sql_for_columns(self, data, qn):
"""
Returns the SQL fragment used for the left-hand side of a column
constraint (for example, the "T1.foo" portion in the clause
"WHERE ... T1.foo = 6").
"""
table_alias, name, db_type = data
if table_alias:
lhs = '%s.%s' % (qn(table_alias), qn(name))
else:
lhs = qn(name)
return connection.ops.field_cast_sql(db_type) % lhs
def relabel_aliases(self, change_map, node=None):
"""
Relabels the alias values of any children. 'change_map' is a dictionary
@ -188,8 +208,10 @@ class WhereNode(tree.Node):
elif isinstance(child, tree.Node):
self.relabel_aliases(change_map, child)
else:
if child[0] in change_map:
node.children[pos] = (change_map[child[0]],) + child[1:]
elt = list(child[0])
if elt[0] in change_map:
elt[0] = change_map[elt[0]]
node.children[pos] = (tuple(elt),) + child[1:]
class EverythingNode(object):
"""
@ -211,3 +233,33 @@ class NothingNode(object):
def relabel_aliases(self, change_map, node=None):
return
class Constraint(object):
"""
An object that can be passed to WhereNode.add() and knows how to
pre-process itself prior to including in the WhereNode.
"""
def __init__(self, alias, col, field):
self.alias, self.col, self.field = alias, col, field
def process(self, lookup_type, value):
"""
Returns a tuple of data suitable for inclusion in a WhereNode
instance.
"""
# Because of circular imports, we need to import this here.
from django.db.models.base import ObjectDoesNotExist
try:
if self.field:
params = self.field.get_db_prep_lookup(lookup_type, value)
db_type = self.field.db_type()
else:
# This branch is used at times when we add a comparison to NULL
# (we don't really want to waste time looking up the associated
# field object at the calling location).
params = Field().get_db_prep_lookup(lookup_type, value)
db_type = None
except ObjectDoesNotExist:
raise EmptyShortCircuit
return (self.alias, self.col, db_type), params

13
tests/regressiontests/queries/models.py
View File

@ -973,19 +973,6 @@ relations.
>>> len([x[2] for x in q.alias_map.values() if x[2] == q.LOUTER and q.alias_refcount[x[1]]])
1
A check to ensure we don't break the internal query construction of GROUP BY
and HAVING. These aren't supported in the public API, but the Query class knows
about them and shouldn't do bad things.
>>> qs = Tag.objects.values_list('parent_id', flat=True).order_by()
>>> qs.query.group_by = ['parent_id']
>>> qs.query.having = ['count(parent_id) > 1']
>>> expected = [t3.parent_id, t4.parent_id]
>>> expected.sort()
>>> result = list(qs)
>>> result.sort()
>>> expected == result
True
Make sure bump_prefix() (an internal Query method) doesn't (re-)break. It's
sufficient that this query runs without error.
>>> qs = Tag.objects.values_list('id', flat=True).order_by('id')