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queryset-refactor: Added a way to change the prefix of all aliases in a query.

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This fixes the last few corner cases for nested queries that had overlapping
aliases. Also tidies up a couple of internal data structures.


git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7231 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2008-03-12 14:52:12 +00:00
parent 428450b7a9
commit c8b33b824b
2 changed files with 53 additions and 37 deletions
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87
django/db/models/sql/query.py
View File

@ -44,7 +44,6 @@ class Query(object):
self.connection = connection self.connection = connection
self.alias_map = {} # Maps alias to table name self.alias_map = {} # Maps alias to table name
self.table_map = {} # Maps table names to list of aliases. self.table_map = {} # Maps table names to list of aliases.
self.join_map = {} # Maps join_tuple to list of aliases.
self.rev_join_map = {} # Reverse of join_map. self.rev_join_map = {} # Reverse of join_map.
self.quote_cache = {} self.quote_cache = {}
self.default_cols = True self.default_cols = True
@ -128,8 +127,7 @@ class Query(object):
obj.connection = self.connection obj.connection = self.connection
obj.alias_map = copy.deepcopy(self.alias_map) obj.alias_map = copy.deepcopy(self.alias_map)
obj.table_map = self.table_map.copy() obj.table_map = self.table_map.copy()
obj.join_map = copy.deepcopy(self.join_map) obj.rev_join_map = self.rev_join_map.copy()
obj.rev_join_map = copy.deepcopy(self.rev_join_map)
obj.quote_cache = {} obj.quote_cache = {}
obj.default_cols = self.default_cols obj.default_cols = self.default_cols
obj.default_ordering = self.default_ordering obj.default_ordering = self.default_ordering
@ -584,42 +582,65 @@ class Query(object):
if self.alias_map[alias][ALIAS_NULLABLE]: if self.alias_map[alias][ALIAS_NULLABLE]:
self.alias_map[alias][ALIAS_JOIN][JOIN_TYPE] = self.LOUTER self.alias_map[alias][ALIAS_JOIN][JOIN_TYPE] = self.LOUTER
def change_alias(self, old_alias, new_alias): def change_aliases(self, change_map):
""" """
Changes old_alias to new_alias, relabelling any references to it in Changes the aliases in change_map (which maps old-alias -> new-alias),
select columns and the where clause. relabelling any references to them in select columns and the where
clause.
""" """
assert new_alias not in self.alias_map assert set(change_map.keys()).intersection(set(change_map.values())) == set()
# 1. Update references in "select" and "where". # 1. Update references in "select" and "where".
change_map = {old_alias: new_alias}
self.where.relabel_aliases(change_map) self.where.relabel_aliases(change_map)
for pos, col in enumerate(self.select): for pos, col in enumerate(self.select):
if isinstance(col, (list, tuple)): if isinstance(col, (list, tuple)):
if col[0] == old_alias: self.select[pos] = (change_map.get(old_alias, old_alias), col[1])
self.select[pos] = (new_alias, col[1])
else: else:
col.relabel_aliases(change_map) col.relabel_aliases(change_map)
# 2. Rename the alias in the internal table/alias datastructures. # 2. Rename the alias in the internal table/alias datastructures.
alias_data = self.alias_map[old_alias] for old_alias, new_alias in change_map.items():
alias_data[ALIAS_JOIN][RHS_ALIAS] = new_alias alias_data = self.alias_map[old_alias]
table_aliases = self.table_map[alias_data[ALIAS_TABLE]] alias_data[ALIAS_JOIN][RHS_ALIAS] = new_alias
for pos, alias in enumerate(table_aliases): self.rev_join_map[new_alias] = self.rev_join_map[old_alias]
if alias == old_alias: del self.rev_join_map[old_alias]
table_aliases[pos] = new_alias table_aliases = self.table_map[alias_data[ALIAS_TABLE]]
break for pos, alias in enumerate(table_aliases):
self.alias_map[new_alias] = alias_data if alias == old_alias:
del self.alias_map[old_alias] table_aliases[pos] = new_alias
for pos, alias in enumerate(self.tables): break
if alias == old_alias: self.alias_map[new_alias] = alias_data
self.tables[pos] = new_alias del self.alias_map[old_alias]
break for pos, alias in enumerate(self.tables):
if alias == old_alias:
self.tables[pos] = new_alias
break
# 3. Update any joins that refer to the old alias. # 3. Update any joins that refer to the old alias.
for data in self.alias_map.values(): for data in self.alias_map.values():
if data[ALIAS_JOIN][LHS_ALIAS] == old_alias: alias = data[ALIAS_JOIN][LHS_ALIAS]
data[ALIAS_JOIN][LHS_ALIAS] = new_alias if alias in change_map:
data[ALIAS_JOIN][LHS_ALIAS] = change_map[alias]
def bump_prefix(self):
"""
Changes the alias prefix to the next letter in the alphabet and
relabels all the aliases. Even tables that previously had no alias will
get an alias after this call (it's mostly used for nested queries and
the outer query will already be using the non-aliased table name).
Subclasses who create their own prefix should override this method to
produce a similar result (a new prefix and relabelled aliases).
"""
assert ord(self.alias_prefix) < ord('Z')
self.alias_prefix = chr(ord(self.alias_prefix) + 1)
change_map = {}
prefix = self.alias_prefix
for pos, alias in enumerate(self.tables):
new_alias = '%s%d' % (prefix, pos)
change_map[alias] = new_alias
self.tables[pos] = new_alias
self.change_aliases(change_map)
def get_initial_alias(self): def get_initial_alias(self):
""" """
@ -681,15 +702,12 @@ class Query(object):
is_table = False is_table = False
t_ident = (lhs_table, table, lhs_col, col) t_ident = (lhs_table, table, lhs_col, col)
if not always_create: if not always_create:
aliases = self.join_map.get(t_ident) for alias, row in self.rev_join_map.items():
if aliases: if t_ident == row and alias not in exclusions:
for alias in aliases: self.ref_alias(alias)
if alias not in exclusions: if promote and self.alias_map[alias][ALIAS_NULLABLE]:
self.ref_alias(alias) self.alias_map[alias][ALIAS_JOIN][JOIN_TYPE] = self.LOUTER
if promote and self.alias_map[alias][ALIAS_NULLABLE]: return alias
self.alias_map[alias][ALIAS_JOIN][JOIN_TYPE] = \
self.LOUTER
return alias
# If we get to here (no non-excluded alias exists), we'll fall # If we get to here (no non-excluded alias exists), we'll fall
# through to creating a new alias. # through to creating a new alias.
@ -708,7 +726,6 @@ class Query(object):
join[JOIN_TYPE] = None join[JOIN_TYPE] = None
self.alias_map[alias][ALIAS_JOIN] = join self.alias_map[alias][ALIAS_JOIN] = join
self.alias_map[alias][ALIAS_NULLABLE] = nullable self.alias_map[alias][ALIAS_NULLABLE] = nullable
self.join_map.setdefault(t_ident, []).append(alias)
self.rev_join_map[alias] = t_ident self.rev_join_map[alias] = t_ident
return alias return alias

3
django/db/models/sql/subqueries.py
View File

@ -158,8 +158,7 @@ class UpdateQuery(Query):
# We need to use a sub-select in the where clause to filter on things # We need to use a sub-select in the where clause to filter on things
# from other tables. # from other tables.
query = self.clone(klass=Query) query = self.clone(klass=Query)
alias = '%s0' % self.alias_prefix query.bump_prefix()
query.change_alias(query.tables[0], alias)
self.add_fields([query.model._meta.pk.name]) self.add_fields([query.model._meta.pk.name])
# Now we adjust the current query: reset the where clause and get rid # Now we adjust the current query: reset the where clause and get rid