base.py 文件源码

def __init__(self, name, column_name, schema=None,
                        existing_type=None,
                        existing_nullable=None,
                        existing_server_default=None):
        super(AlterColumn, self).__init__(name, schema=schema)
        self.column_name = column_name
        self.existing_type=sqltypes.to_instance(existing_type) \
                        if existing_type is not None else None
        self.existing_nullable=existing_nullable
        self.existing_server_default=existing_server_default