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# mapper/util.py
# Copyright (C) 2005,2006 Michael Bayer mike_mp@zzzcomputing.com
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
import sets
import sqlalchemy.sql as sql
class CascadeOptions(object):
"""keeps track of the options sent to relation().cascade"""
def __init__(self, arg=""):
values = sets.Set([c.strip() for c in arg.split(',')])
self.delete_orphan = "delete-orphan" in values
self.delete = "delete" in values or self.delete_orphan or "all" in values
self.save_update = "save-update" in values or "all" in values
self.merge = "merge" in values or "all" in values
self.expunge = "expunge" in values or "all" in values
self.refresh_expire = "refresh-expire" in values or "all" in values
def __contains__(self, item):
return getattr(self, item.replace("-", "_"), False)
def polymorphic_union(table_map, typecolname, aliasname='p_union'):
colnames = sets.Set()
colnamemaps = {}
for key in table_map.keys():
table = table_map[key]
# mysql doesnt like selecting from a select; make it an alias of the select
if isinstance(table, sql.Select):
table = table.alias()
table_map[key] = table
m = {}
for c in table.c:
colnames.add(c.name)
m[c.name] = c
colnamemaps[table] = m
def col(name, table):
try:
return colnamemaps[table][name]
except KeyError:
return sql.null().label(name)
result = []
for type, table in table_map.iteritems():
if typecolname is not None:
result.append(sql.select([col(name, table) for name in colnames] + [sql.column("'%s'" % type).label(typecolname)], from_obj=[table]))
else:
result.append(sql.select([col(name, table) for name in colnames], from_obj=[table]))
return sql.union_all(*result).alias(aliasname)
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