# Copyright 2019 Google LLC

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# https://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Holds information about a specific migration."""

from typing import Callable, Optional

from spanner_orm.admin import update

def no_update_callable() -> update.MigrationUpdate:

return update.NoUpdate()

class Migration:

"""Holds information about a specific migration."""

def __init__(

self,

migration_id: str,

prev_migration_id: Optional[str],

upgrade: Optional[Callable[[], update.MigrationUpdate]] = None,

downgrade: Optional[Callable[[], update.MigrationUpdate]] = None,

):

self._id = migration_id

self._prev = prev_migration_id

self._upgrade = upgrade or no_update_callable

self._downgrade = downgrade or no_update_callable

@property

def migration_id(self) -> str:

return self._id

@property

def prev_migration_id(self) -> Optional[str]:

return self._prev

@property

def upgrade(self) -> Optional[Callable[[], update.MigrationUpdate]]:

return self._upgrade

@property

def downgrade(self) -> Optional[Callable[[], update.MigrationUpdate]]:

return self._downgrade