sqlalchemy.exc.ArgumentError: Mapper mapped class ..could not assemble any primary key columns

在sqlalchemy创建数据模型时，出现
sqlalchemy.exc.ArgumentError: Mapper mapped class 类名->表名 could not assemble any primary key columns for mapped table 表名

SAWarning: Ignoring declarative-like tuple value of attribute ‘user_id’: possibly a copy-and-paste error with a comma accidentally placed at the end of the line?
“accidentally placed at the end of the line?” % k

这两个问题都是数据模型字段之间多了一个逗号。