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TABLE_TYPE = object()
VIEW_TYPE = object()
class NameMissingException(Exception):
pass
def drop_views(manager, views):
"""
Drops the specified views from the database
If a specified view does not exist in the database, this method fails
without modification
@param manager the migration manager
@param views the views to drop
"""
check_exists(manager, views, VIEW_TYPE)
for view in views:
manager.execute('DROP VIEW `%s`' % view)
def rename(manager, mapping):
"""
Renames specified tables in the database
Use this to rename a specified set of tables in a database. If a source in
the mapping does not exist, this method fails without modification.
@param manager the migration manager
@param mapping a dictionary of orig_name => new_name. Any table not matching
an entry in this dictionary will not be renamed
"""
check_exists(manager, (table for table, _ in mapping.iteritems()),
TABLE_TYPE)
for orig_name, new_name in mapping.iteritems():
manager.execute('RENAME TABLE `%s` TO `%s`' % (orig_name, new_name))
def move_tables(manager, src_manager, tables):
"""
Moves the specified tables from another database
If a table does not exist in the source database, this method fails without
modification
@param manager the migration manager
@param src_manager a migration manager that handles the source database
@param tables a list of tables to move
"""
check_exists(src_manager, tables, TABLE_TYPE)
for table in tables:
manager.execute('RENAME TABLE `%(db)s`.`%(table)s` TO `%(table)s`'
% dict(db=src_manager.get_db_name(), table=table))
def drop_database(manager):
"""
Drops the database that the specified manager controls
@param manager the migration manager
"""
manager.execute('DROP DATABASE `%s`' % manager.get_db_name())
def check_exists(manager, names, type):
"""
Checks if the tables or views exists.
Raise an Exception if any of the names do not exist
@param manager the migration manager
@param names the table/view names
@param type one of 'TABLE' or 'VIEW'
"""
if type == TABLE_TYPE:
info_table = 'TABLES'
elif type == VIEW_TYPE:
info_table = 'VIEWS'
else:
raise Exception("type parameter must be either TABLE_TYPE or VIEW_TYPE")
query = ('SELECT table_name FROM information_schema.%s '
'WHERE table_schema = %%s' % info_table)
rows = manager.execute(query, manager.get_db_name())
existing_names = [row[0] for row in rows]
for name in names:
if name not in existing_names:
raise NameMissingException(
'%s missing from database, stopping' % name)
def check_index_exists(manager, table_name, index_name):
"""
Checks if a particular index exists on the table
@param manager the migration manager
@param table_name the table to check
@param index_name the index to check
"""
query = ('SELECT 1 FROM information_schema.statistics '
'WHERE table_schema = %s AND table_name = %s AND index_name = %s')
rows = manager.execute(query, manager.get_db_name(), table_name, index_name)
return bool(rows)
DJANGO_AUTH_TABLES = ('auth_group', 'auth_group_permissions', 'auth_permission')
def auth_tables_exist(manager):
try:
check_exists(manager, DJANGO_AUTH_TABLES, TABLE_TYPE)
return True
except NameMissingException:
return False