相关疑难解决方法(0)

当我尝试创建数据库模式迁移时,我遇到了这个奇怪的错误.你能帮我弄清楚出了什么问题吗？

$ python app.py db upgrade
[skipped]
sqlalchemy.exc.ArgumentError: Mapper Mapper|EssayStateAssociations|essay_associations could not assemble any primary key columns for mapped table 'essay_associations'

我的模特:

class EssayStateAssociations(db.Model):
    __tablename__ = 'essay_associations'

    application_essay_id = db.Column(
        db.Integer,
        db.ForeignKey("application_essay.id"),
        primary_key=True),
    theme_essay_id = db.Column(
        db.Integer,
        db.ForeignKey("theme_essay.id"),
        primary_key=True),
    state = db.Column(db.String, default="pending")

为了了解有关python的更多信息,我制作了以下简单脚本:

#!/usr/bin/env python
# coding=utf-8
# -*- Mode: python; c-basic-offset: 4 -*-

from sqlalchemy import *
from sqlalchemy.orm import sessionmaker
from sqlalchemy.orm import mapper

db=create_engine('postgresql://somepassword:someuser@127.0.0.1/hello')
db.echo = False
metadata = MetaData(db)

people=Table('people',metadata,autoload=True)

class People(object):
    pass

people_mapper=mapper(People,people)

db_session=sessionmaker()
db_session.configure(bind=db)

lewis_hamilton=People()
lewis_hamilton.name='Lewis'
lewis_hamilton.surname='Hamilton'
lewis_hamilton.age=44

db_session.save(lewis_hamilton)
db_session.flush()

我使用下表将"Lewis Hamilton"插入(直接来自psql):

                                 Table "public.people"
 Column  |         Type          |                      Modifiers                      
---------+-----------------------+-----------------------------------------------------
 id      | integer               | not null default nextval('people_id_seq'::regclass)
 name    | character varying(60) | 
 surname | character varying(60) | 
 age     | smallint              | 

但是当我运行脚本时,我收到以下错误:

sqlalchemy.exc.ArgumentError:Mapper Mapper | …