Wait for Callbacks to complete before returning to the user

Question

I have a dynamic case where user will post a array of data which i need to insert into the database in different rows. How do i wait for the calls back to complete before returning success or failure to the user.

I tried using promise but it returns this

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): TypeError: Cannot read property 'Symbol(Symbol.iterator)' of undefined (node:6216) DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

My trails with promises

req.targetting.forEach(data => {
      let s = {};
      if (data.value == '' || data.value.length == 0) {
        s = 99;
      } else {
        s = data.status;
      }
      let promises =  new Promise((resolve, reject) => {
        XXX.upsertWithWhere(where clause,data, (err, data) => { // a loopback method
            if (err) {
              return reject(err);
            }
            return resolve(data);
          });
      });
      Promise.all(promises).then((err, data) => {
        if (err) {
          return callback(err);
        }
        callback(null, data);
      });
    });
  };

I thought of put promises out side but still the same error with rejection id 3

The signature for the upsert method

PersistedModel.upsertWithWhere([where], data, callback)

Answer 1

I guess something like this should be fine(I didnt test this code)

let promises = [];
req.targetting.forEach(data => {
let s = {};
if (data.value == '' || data.value.length == 0) {
  s = 99;
} else {
  s = data.status;
}
let promise =  new Promise((resolve, reject) => {
  XXX.upsertWithWhere(whereclause,data, (err, data) => { // a loopback 
  //method
  if (err) {
    return reject(err);
  }
    return resolve(data);
  });
});
promises.push(promise);
});
Promise.all(promises).then((data) => {
  return data;
})
.catch((err) => {
  return err;
});