Test current database revision is at head(s)

A recipe to determine if a database schema is up to date in terms of applying Alembic migrations. May be useful for test or installation suites to determine if the target database is up to date. Makes use of the MigrationContext.get_current_heads() as well as ScriptDirectory.get_heads() methods so that it accommodates for a branched revision tree:

在应用 Alembic 迁移方面确定数据库模式是否是最新的配方。 可能有助于测试或安装套件确定目标数据库是否是最新的。 使用 MigrationContext.get_current_heads() 和 ScriptDirectory.get_heads() 方法，以便它适应分支的修订树：

from alembic import config, script
from alembic.runtime import migration
from sqlalchemy import engine


def check_current_head(alembic_cfg, connectable):
    # type: (config.Config, engine.Engine) -> bool
    directory = script.ScriptDirectory.from_config(alembic_cfg)
    with connectable.begin() as connection:
        context = migration.MigrationContext.configure(connection)
        return set(context.get_current_heads()) == set(directory.get_heads())

e = engine.create_engine("mysql://scott:tiger@localhost/test", echo=True)
cfg = config.Config("alembic.ini")
print(check_current_head(cfg, e))

同样参考:

• MigrationContext.get_current_heads()
• ScriptDirectory.get_heads()