让我们重构第一个blog，将其命名为promisefunction。它可以用以下方式编写，以便它始终返回承诺。

const promiseFunction = function (req, res, next) {
// I am assuming it is a express middleware and res is passed as the function arguments.
return new Promise((resolve, reject) => {
    console.log(email, password);
    var isAuthenticated = false;
    isAuthenticated = model.authenticate(email, password)
        .then(function (result) {
            //console.log(model.authenticate(email, password));
            console.log("is Authenticated ?: ", isAuthenticated);
            if (isAuthenticated) {
                console.log(isAuthenticated);
                console.log("Success!");
                res.render('/home');
                return resolve()
            }
            else {
                console.log("ko");
                res.redirect("/");
                return resolve()
            }
        }).catch(function (error) {
            console.log(error);
            return reject(error)
        });
});
}

以上代码将始终返回承诺。更好的方法是

const promiseFunction = function (req, res, next) {
// I am assuming it is a express middleware and res is passed as the function arguments.
return model.authenticate(email, password)
    .then(function ({ isAuthenticated }) {
        //console.log(model.authenticate(email, password));
        console.log("is Authenticated ?: ", isAuthenticated);
        if (isAuthenticated) {
            console.log(isAuthenticated);
            console.log("Success!");
            res.render('/home');
        }
        else {
            console.log("ko");
            res.redirect("/");
        }
    })
}

身份验证功能是：

User.prototype.authenticate = function (email, password) {
connection = this.connection;

return new Promise(function (resolve, reject) {
    connection.query('SELECT * FROM users WHERE email = ? AND Password = ? AND is_deleted = 0', [email, password], function (error, results, fields) {
        if (error) {
            console.log("error ocurred", error);
            return reject(error);
        }
        else {
            var newResponse = Object.assign({}, response, {isAuthenticated: true})
            return resolve(newResponse);
        }
    });
});
};