javascript - 在模型验证中获取 this.id 返回 undefined

Question

我在字段的验证中将 this 设置为 undefined，但即使我在 Sequelize.define 的第三个参数中设置，也会发生同样的情况使用其他字段作为 documentation描述。

module.exports = function (sequelize, DataTypes) {

const User = sequelize.define(
    'User', 
    {...}, //all fields here
    {
        freezeTableName: true,
        paranoid: true,
        validate: {
            isPasswordRepeated: () => {
                console.log(this.id, this.password);
            }
        }
    }
);

}

在这段代码中，console.log 输出undefined undefined。如果我使用密码验证，对于 this.id 仍然得到 undefined，但通过参数接收密码。我一直在寻找解决方案，但这似乎是一个罕见的问题，只找到了 this abandoned issue在 GitHub 上。有没有其他方法可以获取this.id？

Sequelize 版本 4.42.0

Answer 1

您没有理解“this”的上下文。

Inside a function, the value of this depends on how the function is called.

...

Since the following code is not in strict mode, and because the value of this is not set by the call, this will default to the global object, which is window in a browser.

...

In strict mode, however, if the value of this is not set when entering an execution context, it remains as undefined.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this#Function_context