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# GNU MediaGoblin -- federated, autonomous media hosting
# Copyright (C) 2011 MediaGoblin contributors. See AUTHORS.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
class MigrationManager(object):
"""
Migration handling tool.
Takes information about a database, lets you update the database
to the latest migrations, etc.
"""
def __init__(self, name, models, migration_registry, database):
"""
Args:
- name: identifier of this section of the database
- database: database we're going to migrate
- migration_registry: where we should find all migrations to
run
"""
self.name = name
self.models = models
self.database = database
self.migration_registry = migration_registry
self._sorted_migrations = None
# For convenience
from mediagoblin.db.sql.models import MigrationData
self.migration_model = MigrationData
self.migration_table = MigrationData.__table__
@property
def sorted_migrations(self):
"""
Sort migrations if necessary and store in self._sorted_migrations
"""
if not self._sorted_migrations:
self._sorted_migrations = sorted(
self.migration_registry.items(),
# sort on the key... the migration number
key=lambda migration_tuple: migration_tuple[0])
return self._sorted_migrations
def latest_migration(self):
"""
Return a migration number for the latest migration, or 0 if
there are no migrations.
"""
if self.sorted_migrations:
return self.sorted_migrations[-1][0]
else:
# If no migrations have been set, we start at 0.
return 0
def database_current_migration(self):
"""
Return the current migration in the database.
"""
# TODO
def set_current_migration(self, migration_number):
"""
Set the migration in the database to migration_number
"""
# TODO
pass
def migrations_to_run(self):
"""
Get a list of migrations to run still, if any.
Note that calling this will set your migration version to the
latest version if it isn't installed to anything yet!
"""
## TODO
# self._ensure_current_migration_record()
#
# db_current_migration = self.database_current_migration()
#
# return [
# (migration_number, migration_func)
# for migration_number, migration_func in self.sorted_migrations
# if migration_number > db_current_migration]
pass
def init_or_migrate(self):
# Find out what migration number, if any, this database data is at,
# and what the latest is.
# Is this our first time? Is there even a table entry for
# this identifier?
#
# If so:
# - create all tables
# - create record in migrations registry
# - print / inform the user
# - return 'inited'
# Run migrations, if appropriate.
# If ran migrations, return 'migrated'. Otherwise, return None.
pass
class RegisterMigration(object):
"""
Tool for registering migrations
Call like:
@RegisterMigration(33)
def update_dwarves(database):
[...]
This will register your migration with the default migration
registry. Alternately, to specify a very specific
migration_registry, you can pass in that as the second argument.
Note, the number of your migration should NEVER be 0 or less than
0. 0 is the default "no migrations" state!
"""
def __init__(self, migration_number, migration_registry):
assert migration_number > 0, "Migration number must be > 0!"
assert migration_number not in migration_registry, \
"Duplicate migration numbers detected! That's not allowed!"
self.migration_number = migration_number
self.migration_registry = migration_registry
def __call__(self, migration):
self.migration_registry[self.migration_number] = migration
return migration
def assure_migrations_table_setup(db):
"""
Make sure the migrations table is set up in the database.
"""
from mediagoblin.db.sql.models import MigrationData
if not MigrationData.__table__.exists(db):
MigrationData.metadata.create_all(
db, tables=[MigrationData.__table__])
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