Flask SQLAlchemy外键约束错误格式不正确

时间:2019-05-13 09:17:30

标签: python flask

我编写了以下代码:

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    first_name = db.Column(db.String(255), nullable=True)
    last_name = db.Column(db.String(255), nullable=True)
    email = db.Column(db.String(255), unique=True, nullable=False)

    password_expires_at = db.Column(db.DateTime, nullable=False)
    active = db.Column(db.Boolean, nullable=False)

    created_at = db.Column(db.DateTime, nullable=False,
        default=datetime.utcnow)
    updated_at = db.Column(db.DateTime, nullable=False,
        default=datetime.utcnow)

    session_id = db.Column(db.Integer, db.ForeignKey('session.id'),
        nullable=False)

class Session(db.Model):
    id = db.Column(db.String(255), primary_key=True)
    ip = db.Column(db.String(255), unique=True, nullable=False)
    user = db.relationship('User', backref='session')

db.create_all()

运行Flask时出现以下错误:

sqlalchemy.exc.OperationalError: (MySQLdb._exceptions.OperationalError) (1005, 'Can\'t create table `bugbot`.`user` (errno: 150 "Foreign key constraint is incorrectly formed")')
[SQL: 
CREATE TABLE user (
        id INTEGER NOT NULL AUTO_INCREMENT, 
        first_name VARCHAR(255), 
        last_name VARCHAR(255), 
        email VARCHAR(255) NOT NULL, 
        password_expires_at DATETIME NOT NULL, 
        active BOOL NOT NULL, 
        created_at DATETIME NOT NULL, 
        updated_at DATETIME NOT NULL, 
        session_id INTEGER NOT NULL, 
        PRIMARY KEY (id), 
        UNIQUE (email), 
        CHECK (active IN (0, 1)), 
        FOREIGN KEY(session_id) REFERENCES session (id)
)

]

我遵循了获得此代码的教程,所以我不知道自己在做什么错。有人可以帮我吗?

1 个答案:

答案 0 :(得分:3)

您要在(User.session_id上施加约束的列的类型为Integer,而它所引用的列(Session.id)的类型为String!这就是为什么它会失败,使两种类型都兼容,然后再次运行,它应该可以工作。