1 TABLE_TYPE = object() 2 VIEW_TYPE = object() 3 4 5 class NameMissingException(Exception): 6 pass 7 8 9 def drop_views(manager, views): 10 """ 11 Drops the specified views from the database 12 13 If a specified view does not exist in the database, this method fails 14 without modification 15 16 @param manager the migration manager 17 @param views the views to drop 18 """ 19 check_exists(manager, views, VIEW_TYPE) 20 for view in views: 21 manager.execute('DROP VIEW `%s`' % view) 22 23 24 def rename(manager, mapping): 25 """ 26 Renames specified tables in the database 27 28 Use this to rename a specified set of tables in a database. If a source in 29 the mapping does not exist, this method fails without modification. 30 31 @param manager the migration manager 32 @param mapping a dictionary of orig_name => new_name. Any table not matching 33 an entry in this dictionary will not be renamed 34 """ 35 check_exists(manager, (table for table, _ in mapping.iteritems()), 36 TABLE_TYPE) 37 for orig_name, new_name in mapping.iteritems(): 38 manager.execute('RENAME TABLE `%s` TO `%s`' % (orig_name, new_name)) 39 40 41 def move_tables(manager, src_manager, tables): 42 """ 43 Moves the specified tables from another database 44 45 If a table does not exist in the source database, this method fails without 46 modification 47 48 @param manager the migration manager 49 @param src_manager a migration manager that handles the source database 50 @param tables a list of tables to move 51 """ 52 check_exists(src_manager, tables, TABLE_TYPE) 53 for table in tables: 54 manager.execute('RENAME TABLE `%(db)s`.`%(table)s` TO `%(table)s`' 55 % dict(db=src_manager.get_db_name(), table=table)) 56 57 58 def drop_database(manager): 59 """ 60 Drops the database that the specified manager controls 61 62 @param manager the migration manager 63 """ 64 manager.execute('DROP DATABASE `%s`' % manager.get_db_name()) 65 66 67 def check_exists(manager, names, type): 68 """ 69 Checks if the tables or views exists. 70 71 Raise an Exception if any of the names do not exist 72 73 @param manager the migration manager 74 @param names the table/view names 75 @param type one of 'TABLE' or 'VIEW' 76 """ 77 if type == TABLE_TYPE: 78 info_table = 'TABLES' 79 elif type == VIEW_TYPE: 80 info_table = 'VIEWS' 81 else: 82 raise Exception("type parameter must be either TABLE_TYPE or VIEW_TYPE") 83 84 query = ('SELECT table_name FROM information_schema.%s ' 85 'WHERE table_schema = %%s' % info_table) 86 rows = manager.execute(query, manager.get_db_name()) 87 existing_names = [row[0] for row in rows] 88 89 for name in names: 90 if name not in existing_names: 91 raise NameMissingException( 92 '%s missing from database, stopping' % name) 93 94 95 def check_index_exists(manager, table_name, index_name): 96 """ 97 Checks if a particular index exists on the table 98 99 @param manager the migration manager 100 @param table_name the table to check 101 @param index_name the index to check 102 """ 103 query = ('SELECT 1 FROM information_schema.statistics ' 104 'WHERE table_schema = %s AND table_name = %s AND index_name = %s') 105 rows = manager.execute(query, manager.get_db_name(), table_name, index_name) 106 return bool(rows) 107 108 109 DJANGO_AUTH_TABLES = ('auth_group', 'auth_group_permissions', 'auth_permission') 110 111 def auth_tables_exist(manager): 112 try: 113 check_exists(manager, DJANGO_AUTH_TABLES, TABLE_TYPE) 114 return True 115 except NameMissingException: 116 return False 117