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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
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commit 6dd2b5468fa275d53aa60fdcaff8c28bdc5e9c25 1 parent 3b64871
@malcolmt malcolmt authored
View
21 django/db/models/sql/query.py
@@ -1104,19 +1104,7 @@ def add_filter(self, filter_expr, connector=AND, negate=False, trim=False,
# 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 @@ def add_filter(self, filter_expr, connector=AND, negate=False, trim=False,
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 @@ def add_filter(self, filter_expr, connector=AND, negate=False, trim=False,
# 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)
View
12 django/db/models/sql/subqueries.py
@@ -49,7 +49,7 @@ def delete_batch_related(self, pk_list):
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 @@ def delete_batch_related(self, pk_list):
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 @@ def delete_batch(self, pk_list):
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 @@ def clear_related(self, related_field, pk_list):
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')]
View
71 django/db/models/sql/where.py
@@ -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 @@ def as_sql(self, node=None, qn=None):
(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
View
31 django/utils/tree.py
@@ -29,6 +29,22 @@ def __init__(self, children=None, connector=None, negated=False):
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 @@ def add(self, node, conn_type):
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 @@ def negate(self):
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 @@ def start_subtree(self, conn_type):
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 @@ def end_subtree(self):
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
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