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Redo the changes in [7773] in a better way. 

This removes some of the leaky abstraction problems (lifting WhereNode
internals into the Query class) from that commit and makes it possible for
extensions to WhereNode to have access to the field instances. It's also
backwards-compatible with pre-[7773] code, which is also better.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7835 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2008-07-04 06:42:58 +00:00
parent 3b6487130a
commit 6dd2b5468f
4 changed files with 84 additions and 51 deletions
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21
django/db/models/sql/query.py
View File

@ -1104,19 +1104,7 @@ class Query(object):
# that's harmless.
self.promote_alias(table)
# To save memory and copying time, convert the value from the Python
# object to the actual value used in the SQL query.
if field:
params = field.get_db_prep_lookup(lookup_type, value)
else:
params = Field().get_db_prep_lookup(lookup_type, value)
if isinstance(value, datetime.datetime):
annotation = datetime.datetime
else:
annotation = bool(value)
self.where.add((alias, col, field.db_type(), lookup_type, annotation,
params), connector)
self.where.add((alias, col, field, lookup_type, value), connector)
if negate:
for alias in join_list:
@ -1126,8 +1114,8 @@ class Query(object):
for alias in join_list:
if self.alias_map[alias][JOIN_TYPE] == self.LOUTER:
j_col = self.alias_map[alias][RHS_JOIN_COL]
entry = Node([(alias, j_col, None, 'isnull', True,
[True])])
entry = self.where_class()
entry.add((alias, j_col, None, 'isnull', True), AND)
entry.negate()
self.where.add(entry, AND)
break
@ -1135,7 +1123,8 @@ class Query(object):
# Leaky abstraction artifact: We have to specifically
# exclude the "foo__in=[]" case from this handling, because
# it's short-circuited in the Where class.
entry = Node([(alias, col, None, 'isnull', True, [True])])
entry = self.where_class()
entry.add((alias, col, None, 'isnull', True), AND)
entry.negate()
self.where.add(entry, AND)

12
django/db/models/sql/subqueries.py
View File

@ -49,7 +49,7 @@ class DeleteQuery(Query):
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.db_type(), 'in', True,
related.field, 'in',
pk_list[offset : offset+GET_ITERATOR_CHUNK_SIZE]),
AND)
self.do_query(related.field.m2m_db_table(), where)
@ -59,11 +59,11 @@ 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.db_type(), 'exact', True,
[ContentType.objects.get_for_model(cls).id]), AND)
w1.add((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.db_type(), 'in', True,
where.add((None, f.m2m_column_name(), f, 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]),
AND)
if w1:
@ -81,7 +81,7 @@ 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.db_type(), 'in', True,
where.add((None, field.column, field, 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]), AND)
self.do_query(self.model._meta.db_table, where)
@ -204,7 +204,7 @@ 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.db_type(), 'in', True,
self.where.add((None, f.column, f, 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]),
AND)
self.values = [(related_field.column, None, '%s')]

71
django/db/models/sql/where.py
View File

@ -27,7 +27,36 @@ class WhereNode(tree.Node):
"""
default = AND
def as_sql(self, node=None, qn=None):
def add(self, data, connector):
"""
Add a node to the where-tree. If the data is a list or tuple, it is
expected to be of the form (alias, col_name, field_obj, lookup_type,
value), which is then slightly munged before being stored (to avoid
storing any reference to field objects). Otherwise, the 'data' is
stored unchanged and can be anything with an 'as_sql()' method.
"""
if not isinstance(data, (list, tuple)):
super(WhereNode, self).add(data, connector)
return
alias, col, field, lookup_type, value = data
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
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)
def as_sql(self, qn=None):
"""
Returns the SQL version of the where clause and the value to be
substituted in. Returns None, None if this node is empty.
@ -36,60 +65,56 @@ class WhereNode(tree.Node):
(generally not needed except by the internal implementation for
recursion).
"""
if node is None:
node = self
if not qn:
qn = connection.ops.quote_name
if not node.children:
if not self.children:
return None, []
result = []
result_params = []
empty = True
for child in node.children:
for child in self.children:
try:
if hasattr(child, 'as_sql'):
sql, params = child.as_sql(qn=qn)
format = '(%s)'
elif isinstance(child, tree.Node):
sql, params = self.as_sql(child, qn)
if child.negated:
format = 'NOT (%s)'
elif len(child.children) == 1:
format = '%s'
else:
format = '(%s)'
else:
# A leaf node in the tree.
sql, params = self.make_atom(child, qn)
format = '%s'
except EmptyResultSet:
if node.connector == AND and not node.negated:
if self.connector == AND and not self.negated:
# We can bail out early in this particular case (only).
raise
elif node.negated:
elif self.negated:
empty = False
continue
except FullResultSet:
if self.connector == OR:
if node.negated:
if self.negated:
empty = True
break
# We match everything. No need for any constraints.
return '', []
if node.negated:
if self.negated:
empty = True
continue
empty = False
if sql:
result.append(format % sql)
result.append(sql)
result_params.extend(params)
if empty:
raise EmptyResultSet
conn = ' %s ' % node.connector
return conn.join(result), result_params
conn = ' %s ' % self.connector
sql_string = conn.join(result)
if sql_string:
if self.negated:
sql_string = 'NOT (%s)' % sql_string
elif len(self.children) != 1:
sql_string = '(%s)' % sql_string
return sql_string, result_params
def make_atom(self, child, qn):
"""
Turn a tuple (table_alias, field_name, db_type, lookup_type,
Turn a tuple (table_alias, column_name, db_type, lookup_type,
value_annot, params) into valid SQL.
Returns the string for the SQL fragment and the parameters to use for

31
django/utils/tree.py
View File

@ -29,6 +29,22 @@ class Node(object):
self.subtree_parents = []
self.negated = negated
# We need this because of django.db.models.query_utils.Q. Q. __init__() is
# problematic, but it is a natural Node subclass in all other respects.
def _new_instance(cls, children=None, connector=None, negated=False):
"""
This is called to create a new instance of this class when we need new
Nodes (or subclasses) in the internal code in this class. Normally, it
just shadows __init__(). However, subclasses with an __init__ signature
that is not an extension of Node.__init__ might need to implement this
method to allow a Node to create a new instance of them (if they have
any extra setting up to do).
"""
obj = Node(children, connector, negated)
obj.__class__ = cls
return obj
_new_instance = classmethod(_new_instance)
def __str__(self):
if self.negated:
return '(NOT (%s: %s))' % (self.connector, ', '.join([str(c) for c
@ -82,7 +98,8 @@ class Node(object):
else:
self.children.append(node)
else:
obj = Node(self.children, self.connector, self.negated)
obj = self._new_instance(self.children, self.connector,
self.negated)
self.connector = conn_type
self.children = [obj, node]
@ -96,7 +113,8 @@ class Node(object):
Interpreting the meaning of this negate is up to client code. This
method is useful for implementing "not" arrangements.
"""
self.children = [Node(self.children, self.connector, not self.negated)]
self.children = [self._new_instance(self.children, self.connector,
not self.negated)]
self.connector = self.default
def start_subtree(self, conn_type):
@ -108,12 +126,13 @@ class Node(object):
if len(self.children) == 1:
self.connector = conn_type
elif self.connector != conn_type:
self.children = [Node(self.children, self.connector, self.negated)]
self.children = [self._new_instance(self.children, self.connector,
self.negated)]
self.connector = conn_type
self.negated = False
self.subtree_parents.append(Node(self.children, self.connector,
self.negated))
self.subtree_parents.append(self.__class__(self.children,
self.connector, self.negated))
self.connector = self.default
self.negated = False
self.children = []
@ -126,7 +145,7 @@ class Node(object):
the current instances state to be the parent.
"""
obj = self.subtree_parents.pop()
node = Node(self.children, self.connector)
node = self.__class__(self.children, self.connector)
self.connector = obj.connector
self.negated = obj.negated
self.children = obj.children