CODEWITHSUNDEEP
node.jsmongodb
Viraj Patil
Viraj Patil

Reputation: 35

Module functions returning undefined in nodejs

I am trying to return a value from module function and calling that function from different file, the function executes but return undefined
below is the code:

this is the module

teacherController={}
teacherController.getClassid = (req)=>{
    Teacher.findOne({token:req.session.user})
    .then((doc)=>{
        var classid = doc.class
        console.log(classid)   // this logs the correct value
        return doc;
    }).catch((err)=>{
        if(err) throw err;
    })
}
module.exports = teacherController;


this is where i am calling the module function

student.get('/ranking',(req,res)=>{
   var classid = teacher_con.getClassid(req);
   console.log(classid);  //this logs: undefined



});


thank you!

Upvotes: 1

Views: 186

Answers (2)

Pushprajsinh Chudasama
Pushprajsinh Chudasama

Reputation: 7949

EDITED
You have to use the promise and thenable function. 

 student.get('/ranking',(req,res)=>{
    teacher_con.getClassid(req).then(res =>{
        console.log(classid);  //you will get the doc
    });
 });

In module

    teacherController.getClassid = (req)=> { //use Promise
        return new Promise((resolve, reject)=>{
            Teacher.findOne({token:req.session.user})
            .exec((err, doc)=>{
                if(err){
                    reject(err);
                }
                else{
                    resolve(doc);
                }

            })
        });
    }

Upvotes: 1

hoangdv
hoangdv

Reputation: 16147

Return a promise in getClassid function:

teacherController = {}
teacherController.getClassid = (req) => {
  return Teacher.findOne({ token: req.session.user })
    .then((doc) => {
      var classid = doc.class
      console.log(classid)   // this logs the correct value
      return doc;
    }).catch((err) => {
      if (err) throw err;
    })
}
module.exports = teacherController;

Then, use async/await at your route:

student.get('/ranking', async (req, res) => {
    var classid = await teacher_con.getClassid(req);
    console.log(classid);
});

Upvotes: 0

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