batch.py 文件源码

def alter_column(self, table_name, column_name,
                     nullable=None,
                     server_default=False,
                     name=None,
                     type_=None,
                     autoincrement=None,
                     **kw
                     ):
        existing = self.columns[column_name]
        existing_transfer = self.column_transfers[column_name]
        if name is not None and name != column_name:
            # note that we don't change '.key' - we keep referring
            # to the renamed column by its old key in _create().  neat!
            existing.name = name
            existing_transfer["name"] = name

        if type_ is not None:
            type_ = sqltypes.to_instance(type_)
            existing.type = type_
            existing_transfer["expr"] = cast(existing_transfer["expr"], type_)
        if nullable is not None:
            existing.nullable = nullable
        if server_default is not False:
            existing.server_default = server_default
        if autoincrement is not None:
            existing.autoincrement = bool(autoincrement)