Question

我想创建一个获取用户信息的函数。当我从函数返回数据时，它返回undefined。当我在函数内部console.log时，它返回所有用户数据。怎么了？

代码：

function user() {
    var uid = socket.request.headers.cookie.uid;
    var pwd = socket.request.headers.cookie.pass;
    if (uid != undefined && pwd != undefined) {
        models.user.findOne({
            '_id': uid,
            'password': pwd
        }, function (err, user) {
            console.log(user);
            return (user) ? user : false;
        });
    } else {
        return false;
    }
}

console.log(user());

Answer 1

你需要一个回调，这是初学者的基本问题

function user(callback) { // receives a callback
    var uid = socket.request.headers.cookie.uid;
    var pwd = socket.request.headers.cookie.pass;
    if (uid != undefined && pwd != undefined) {
        models.user.findOne({
            '_id': uid,
            'password': pwd
        }, callback); // pass callback to mongoose
    } else {
        return callback(new Error("No uid")); // pass callback when no uid
    }
}

user(function(err, userData) { // now you invoke fn to user function
                               // err is err from database or from new Error("No uid")
                               // userData is database User
    if (err) 
        return console.log(err);
    console.log(userData);
    // userData should be used here
    // for example. send this User by socket
    // socket.emit('databaseUser', userData);
});

socket io，mongoose函数返回undefined

1 个答案: