Promise gets rejected even though there is no error. NodeJs

Question

So, I have a piece of code that makes use of Promises and I am using the bluebird library.

The problem is that my promise gets rejected even if there is no error. It completely skips the .then block even for a simple console.log

Here is the code that makes use of promise:

function returnMeetings(query) {
  return new Promise((reject, resolve) => {
    Meeting.find(query, (err, foundMeetings) => {
      if (err) {
           console.log("We have a error")
        reject(err);
      }
      resolve(foundMeetings);
    })
  })
}

And here is the code that makes use of that returnMeetings function

returnMeetings(query)
    .then((data) => {
    console.log("here we are")
    // while (count < stopAt) {
    //   let localData = [];
    //   if (req.params.duration === 'monthly') {
    //     let {
    //       date1,
    //       date2
    //     } = twoDates(count, count);
    //     localData = data.filter((el) => {
    //       if (el.startDate) {
    //         let localDate = new Date(el.startDate);
    //         if (localDate >= date1 && localDate <= date2) {
    //           return el;
    //         }
    //       }
    //     })
    //     if (localData) {
    //       data.push({
    //         data: localData,
    //         month: count
    //       })
    //     }
    //
    //     if (count === stopAt - 1) {
    //       myEmitter.emit('found all meetings')
    //     } else {
    //       count++;
    //     }
    //   }
    // }
  }).catch((err) => {
    res.status(500).json({
      message: err
    })
  })

As you can see in the returnMeetings function i have placed a console.log inside the if(err) block, and it never runs, from that I conclude that I didn't receive any error from the mongoose query.

Still, the code completely skips the .then block, and falls into the catch chain. I have a simple console.log inside the then block, and an interesting thing to note is that the value of err in the callback inside catch block is an array of mongodb documents.

Can someone explain, why is my code behaving in this manner?

Thanks for your help.

Answer 1

the order of resolve/reject in your Promise constructor callback is wrong ... the names of the functions are irrelevant, the first is to resolve, the second is to reject ... you are actually rejecting the promise when you call resolve

ie you could

  return new Promise((fred, wilma) => {

then to resolve the promise, you would call fred(value) and to reject you would call wilma(error)

in other words, the names you give the callback arguments is irrelevant, the position is relevant

change your code as follows:

function returnMeetings(query) {
  return new Promise((resolve, reject) => {
    Meeting.find(query, (err, foundMeetings) => {
      if (err) {
           console.log("We have a error")
        reject(err);
      }
      resolve(foundMeetings);
    })
  })
}