异步watefall不会调用函数

Question

So i am actually woking on a simple program with node.Js and i have an issue using async.waterfall :

• I created a function in my user model that connect the user by accessing the database, here is the code :

   exports.connection = function (login,password) { async.waterfall([ function getLogin(callback){ usersModel.findOne({ login: login }, function (err, res) { if (err){ callback(err,null); return; } if(res != null ){ // test a matching password if the user is found we compare both passwords var userReceived = res.items[0].login; callback(null,userReceived); } }); }, function getPassword(userReceived, callback){ console.log(userReceived); callback(null,'done') } ], function(err){ if (err) { console.error(err); } console.log('success'); }); } 

  Using node-inspector i figured out that the main issue(I think) is that when it enters the waterfall function it doesn't execute the callback function of findOne it literally skips this and directly jump to the getPassword function (which isn't executed too).

so if someone could help me figuring out what's the problem that would be nice since i'm on it for around two days now.

Thank you

EDIT: After adding the different missing cases of tests(which was why the callback didn't worked) I have this connection function:

exports.connection = function (login,password) {

async.waterfall([
function getLogin(callback){
    usersModel.findOne({ login: login }, function (err, res) {
      console.log('login: ',res.login);
      console.log('erreur: ',err);
      if (err){
        callback(err,null);
        return;
      }
      if(!res)
      {
        console.log('getLogin - returned empty res');
        callback('empty res');
      }
      if(res != null ){
        //  test a matching password if the user is found we compare both passwords
        var userReceived = res;
        callback(null,userReceived);
      }
    });
},
function getPassword(userReceived, callback){

    console.log('login received :',userReceived.login);
    var Ulogin = userReceived.login;
    var Upassword = userReceived.password;
 // function that compare the received password with the encrypted 
 //one
    bcrypt.compare(password, Upassword, function(err, isMatch) {
        if (err) {
          console.log(err);
          callback(err,null);
          return;
        }
        else if (isMatch) {
          console.log('Match', isMatch);
          callback(null,isMatch);
        }
        else {
          console.log('the password dont match', isMatch);
          callback('pwd error',null);
        }
    });
},
], function(err){
  if (err) {
    console.error('unexpected error while connecting', err);
    return false;
  }
    console.log('connected successfully');
    return true;
});
}

And in my main file server.js i'm doing currently doing :

var connect = users.connection(login,password);
//the goal is to use the connect variable to know if the connection
//failed or not but it's 'undefined'
if(connect){
       res.send('youyou connecté');
 }
 else {
       res.send('youyou problem');
 }

this absolutely don't work so i tried to use Q library but I have an error saying

"TypeError: Cannot read property 'apply' of undefined at Promise.apply"

here is the code using Q:

  app.post('/signup', function (req, res) {
  var login = req.body.login;
   var password = req.body.password;
   Q.fcall(users.connection(login,password))
   .then(function (connect) {
     if(connect){
       res.send('connected');
     }
     else {
       res.send('problem');
     }
   })
   .catch(function (error) {
       throw error;
   })
   .done();
});

but i am a little bit astonished i thought that by using async.waterfall() i told the function to wait until it received all the callbacks return so i don't understand why the connect variable is 'undefined'?

Answer 1

What I don't understand is - what was the flow exactly? did 'usersModel.findOne' get called?

What I see that is missing here in the getLogin function is a callback in the case that both the 'if' statement return false. in this case you'll get stuck in the first function and you won't advance to 'getPassword' function.

If this still doesn't work, please try executing the following code and report what was printed:

exports.connection = function (login,password) {
async.waterfall([
function getLogin(callback){
      usersModel.findOne({ login: login }, function (err, res) {
        if (err){
          console.log('getLogin - error has occured');
          callback(err,null);
          return;
        }
        if(!res)
        {
          console.log('getLogin - returned empty res');
           callback('empty res');
        }

        console.log('getLogin - result seems OK');

        //  test a matching password if the user is found we compare both passwords
        var userReceived = res.items[0].login;
        callback(null,userReceived);
        }
      });
},
function getPassword(userReceived, callback){
       console.log('getPassword');
      console.log(userReceived);
      callback(null,'done')
    }
], function(err){
  if (err) {
    console.error(err);
  }
    console.log('success');
});
}