如何在SQLAlchemyMigrate中创建方言类型的迁移脚本(HSTORE)

Question

如何创建支持方言数据类型的迁移脚本？

下面是一个模型的例子：

db = SQLAlchemy()

class Event(db.Model):
    __tablename__ = 'event'
    id = db.Column(db.Integer, primary_key=True)
    created_at = db.Column(db.DateTime, server_default=text('NOW()'), primary_key=True)
    data = db.Column(HSTORE)

错误如下：

Column('data', HSTORE), NameError: name 'HSTORE' is not defined

附言：我也在使用Flask sqlalchemy

迁移脚本：

def migrate(db):
    repo, uri = get_config(db)
    migration = repo + '/versions/%03d_migration.py' % (
        api.db_version(uri, repo) + 1)
    tmp_module = imp.new_module('old_model')
    old_model = api.create_model(uri, repo)
    exec old_model in tmp_module.__dict__
    script = api.make_update_script_for_model(uri, repo, tmp_module.meta, db.metadata)
    open(migration, "wt").write(script)
    api.upgrade(uri, repo)
    print 'New migration saved as ' + migration
    print 'Current database version: ' + str(api.db_version(uri, repo))

Answer 1

迁移脚本不知道HSTORE来自哪里。您需要从PostgreSQL方言导入它。在迁移的顶部放上：

from sqlalchemy.dialects.postgresql import HSTORE

Answer 2

您需要导入HSTORE。您可以通过以下操作将导入添加到生成的文件中：

def migrate(db):
    extra_imports = 'from sqlalchemy.dialects.postgresql import HSTOREn'  # your imports
    repo, uri = get_config(db)
    migration = repo + '/versions/%03d_migration.py' % (
        api.db_version(uri, repo) + 1)
    tmp_module = imp.new_module('old_model')
    old_model = api.create_model(uri, repo)
    exec old_model in tmp_module.__dict__
    script = extra_imports + api.make_update_script_for_model(uri, repo, tmp_module.meta, db.metadata)  # just add the imports at the top of the migration script.
    open(migration, "wt").write(script)
    api.upgrade(uri, repo)
    print 'New migration saved as ' + migration
    print 'Current database version: ' + str(api.db_version(uri, repo))