Question

我想在Node.js中返回MySQL查询，但是我遇到了一些问题。

Prob1。 'var userInfo'无法从函数'Authenticate（）'

中获取值

Prob2。抛出将由'dbclient.query'捕获，而不是我能看到的代码。

希望有人可以帮助我。

app.post('/create_member_check', function(req, res) {
    var Authenticate = function () {
        SearchUser(req.body.email, function (isExist) { 
            if (isExist === true)
                throw 101;
            else if (req.body.email === undefined || req.body.email == "")
                throw 102;
            else if (req.body.password === undefined || req.body.password == "")
                throw 103;
            else if (isExist === undefined)
                throw 104;

            var user = {
                "email": req.body.email,
                "password": req.body.password
            };
            AddUser(user);
            // This line cannot return the 'user' for 'Authenticate()' caller.
            return user;
        });
    }

    try {
        var userInfo = Authenticate();
    }
    catch (err) {
        var userInfo;
        if (err == 101)
            userInfo = "[Error] This account already exists.";
        else if (err == 102)
            userInfo = "[Error] Please key in 'email'.";
        else if (err == 103)
            userInfo = "[Error] Please key in 'password'.";
        else if (err == 104)
            userInfo = "[Fatal Error] SearchUser return 'undefined'.";
    }

    res.render("login_system/create_member_check", {
        layout: false,
        pagename: "create",
        authenticate: userInfo
    });
});

SearchUser = function (email, callback) {
    dbclient.query("SELECT * FROM user WHERE email = \"" + email + "\"", function (err, results) {
        if (err || results.length <= 0)
            callback(false);
        else
            callback(true);
    });
}

Answer 1

验证方法不能同步。你应该制作异步方法。试试这个。

app.post('/create_member_check', function(req, res) {
    var Authenticate = function (req, callback) {
        SearchUser(req.body.email, function (isExist) { 
            if (isExist === true)
                return callback(101);
            else if (req.body.email === undefined || req.body.email == "")
                return callback(102);
            else if (req.body.password === undefined || req.body.password == "")
                return callback(103);
            else if (isExist === undefined)
                return callback(104);

            var user = {
                "email": req.body.email,
                "password": req.body.password
            };
            AddUser(user); //this is maybe asynchronous, again
            callback(null, user);
        });
    }

    Authenticate(req, function(err, user){
        var userInfo;
        if (err == 101)
            userInfo = "[Error] This account already exists.";
        else if (err == 102)
            userInfo = "[Error] Please key in 'email'.";
        else if (err == 103)
            userInfo = "[Error] Please key in 'password'.";
        else if (err == 104)
            userInfo = "[Fatal Error] SearchUser return 'undefined'.";

        res.render("login_system/create_member_check", {
            layout: false,
            pagename: "create",
            authenticate: userInfo
        });
    });
});

阅读此article;）

Node.js - 从MySQL查询返回值

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