Node.js异步回调函数不能按要求工作

Question

我想使用Knex.js和mysql在node.js中设计一个注册页面。 下面是代码：

注册页面 `

router.post('/', function(req, res, next){ 
    var fname = req.body.fname; 
    var mname = req.body.mname; 
    var lname = req.body.lname; 
    var email = req.body.email; 
    var uname = req.body.uname; 
    var pwd = req.body.password; 
    var conf_pwd = req.body.conf_password; 
    var tnc = req.body.tnc; 
    var errors = req.validationErrors(); 

    //Validation 
    req.checkBody('fname', 'The First Name is Required').notEmpty(); 
    req.checkBody('mname', 'The Middle Name is Required').notEmpty(); 
    req.checkBody('lname', 'The Last Name is Required').notEmpty(); 
    req.checkBody('uname', 'The Username is Required').notEmpty(); 
    req.checkBody('email', 'The Email is Required').notEmpty(); 

    var rand = Math.floor(Math.random()*90000) + 10000; 

    //hash The password 
    var hashpassword = crypto.createHash('sha512').update(pwd).digest('hex'); 
    var IdVal = email+uname; 
    var IdHash = crypto.createHash('sha512').update(IdVal).digest('hex'); 
    var tstamp = new Date().toString(); 
    //Add The User 
    if(errors){ 
     res.render('register', { 
      errors: errors 
     }); 
    }else{ 

     var newUser = ({ 
      Id: IdHash, 
      FirstName: fname, 
      MiddleName: mname, 
      LastName: lname, 
      Email: email, 
      UserName: uname, 
      HashPassword: hashpassword, 
      ActivationCode: rand.toString(), 
      ActivationStatus : false, 
     }); 
     User.CheckUser(uname, function(stat){ 
      console.log('Stat : ',stat); 
      if(stat == 1){ 
       res.render('register', { 
        uerrors: "The Username Already Exists" 
        }); 
      }else if(stat == 2) 
      { 
       res.render('register', { 
        uerrors: "Error Occured" 
        }); 
      } 
      else if(stat == 0){ 
       User.CreateUser(newUser, function(err){ 
        if (err){ throw err} 
        else{ 
         res.render('register', { 
          message: "Verification Email Sent Please Check Email" 
         }); 
        } 
       }); 
      } 
     }); 
    } 
}); 

所以我想要做的是检查是否存在用户名。如果没有，则创建新用户，然后显示该用户已创建。这里是user.js的

module.exports.CheckUser = function(uname, callback){ 
    knex('Clients') 
     .where({UserName: uname}) 
     .select() 
     .then(function(result){ 
      if(!result || !result[0]){ 
       console.log('User Not Found'); 
       callback(0); 
      }else{ 
       if(result[0].UserName == uname){ 
        callback(1); 
       } 
      } 
     }) 
     .catch(function (err){ 
      console.log(err); 
      callback(2); 
     }); 
} 
module.exports.CreateUser = function(newUser, callback){ 
    knex('Clients') 
     .insert(newUser) 
     .catch(function (err){ 
      callback(err); 
     }); 
} 

这里，究竟是发生在user.js的功能越来越首先执行，然后它显示的用户名已经存在的代码。但用户名刚刚创建。

这里是代码的输出，

GET /register 304 670.944 ms - - 
GET /bootstrap/css/bootstrap.min.css 304 9.677 ms - - 
GET /dist/css/AdminLTE.min.css 304 7.780 ms - - 
GET /plugins/iCheck/square/blue.css 304 7.291 ms - - 
GET /plugins/jQuery/jQuery-2.2.0.min.js 304 2.312 ms - - 
GET /bootstrap/js/bootstrap.min.js 304 2.259 ms - - 
GET /plugins/iCheck/icheck.min.js 304 2.076 ms - - 
GET /bootstrap/fonts/glyphicons-halflings-regular.woff2 304 0.468 ms - - 
GET /plugins/iCheck/square/blue.png 304 0.439 ms - - 
{ method: 'select', 
    options: {}, 
    timeout: false, 
    cancelOnTimeout: false, 
    bindings: [ 'q' ], 
    __knexQueryUid: '99707783-2767-4c37-ae4c-0bd31f98427d', 
    sql: 'select * from `Clients` where `UserName` = ?' } 
User Not Found 
Stat : 0 
{ method: 'insert', 
    options: {}, 
    timeout: false, 
    cancelOnTimeout: false, 
    bindings: 
    [ '41040', 
    false, 
    'ameya.pandya@securelayer7.net', 
    'q', 
    '2e96772232487fb3a058d58f2c310023e07e4017c94d56cc5fae4b54b44605f42a75b0b1f358991f8c6cbe9b68b64e5b2a09d0ad23fcac07ee9a9198a745e1d5', 
    '70b32fc5adc4d2fa6ad5a40d9b6bfe4acc745d0c9c71d47a8266a4d54868198acb29644dc6133fb51cd682dcf1fc72a52278a51ade397ed7f2a38f8ec809e0bf', 
    'q', 
    'q', 
    'q' ], 
    __knexQueryUid: 'dee0340f-c247-4608-a29e-da984cc13e49', 
    sql: 'insert into `Clients` (`ActivationCode`, `ActivationStatus`, `Email`, `FirstName`, `HashPassword`, `Id`, `LastName`, `MiddleName`, `UserName`) values (?, ?, ?, ?, ?, ?, ?, ?, ?)' } 
POST /register - - ms - - 
{ method: 'select', 
    options: {}, 
    timeout: false, 
    cancelOnTimeout: false, 
    bindings: [ 'q' ], 
    __knexQueryUid: 'a58fe912-3a9e-4af0-85ca-e1ba2aa9559b', 
    sql: 'select * from `Clients` where `UserName` = ?' } 
Stat : 1 
POST /register 200 105.596 ms - 3234 

Answer 1

你的输出显示用户不存在。 CheckUser打印'用户未找到'并呼叫callback(0)。 stat等于0，这就是为什么通过以下代码创建新用户的原因。

else if(stat == 0){ 
    User.CreateUser(newUser, function(err){ 
    if (err){ throw err} 
     else{ 
     res.render('register', { 
      message: "Verification Email Sent Please Check Email" 
     }); 
     } 
    }); 
}