Promise.all([..]).then never resolves

Question

I have a number of individual Promises that look like this:

var performancePerMonth = new Promise(function(resolve, reject) {
  var path = some_path;
  getFromApi(path);
});

They all use this method called getFromApi() to perform a request:

function getFromApi(path, callback) {

  request({
    method: 'GET',
    url: base_uri + path,
    headers: { 'TOKEN': 'MY_ACCESS_TOKEN' }
  },

  function (error, response, body) {
    console.log('Status:', response.statusCode);
    console.log('Headers:', JSON.stringify(response.headers));
    console.log('Response:', body);
    return body;
});

Because I need to run the requests together and get an array including all results, I added all individual Promises into a Promise.all:

exports.perform = function(req, response) {
  Promise.all([performancePerMonth, performancePerPlayer,..]).then(function(results) {
    console.log('Then: ', results);
  }).catch(function(err) {
    console.log('ERROR Promise.all');
    console.log('Catch: ', err);
  })
};

The problem is, although the requests are performed fine as I can see from the logs on getFromApi() method, the array of results is never returned. The method runs but apparently never gets to the function inside .then and this:

console.log('Then: ', results);

is never reached (neither the catch function under it).

Seems as if the program runs only until all requests are performed and forgets to return results.

Answer 1

You're never resolving the promise.

var performancePerMonth = new Promise(function(resolve, reject) {
  var path = some_path;
  getFromApi(path, resolve);
});

Your getFromApi function also has a callback but it never gets run. You probably want callback(body); instead of return body;

Answer 2

function getFromApi(path, callback) accepts a callback argument so lets use that as the callback for request instead of the anonymous function you have

function getFromApi(path, callback) {
  request({
    method: 'GET',
    url: base_uri + path,
    headers: { 'TOKEN': 'MY_ACCESS_TOKEN' }
  }, callback);
}

Now lets use that anonymous function, slightly modified to call resolve/reject as required, in performancePerMonth etc

var performancePerMonth = new Promise(function(resolve, reject) {
    var path = some_path;
    getFromApi(path, function (error, response, body) {
        if (error) {
            reject(error);
        } else {
            console.log('Status:', response.statusCode);
            console.log('Headers:', JSON.stringify(response.headers));
            console.log('Response:', body);
            resolve(body);
        }
    });
});

You may want to check response.statusCode is one that indicates a successful request before blindly resolving the body too - many request API's don't consider a non 2xx status returned in the response as an error

so, you may need something like

var performancePerMonth = new Promise(function(resolve, reject) {
    var path = some_path;
    getFromApi(path, function (error, response, body) {
        if (error) {
            reject(error);
        } else {
            console.log('Status:', response.statusCode);
            console.log('Headers:', JSON.stringify(response.headers));
            console.log('Response:', body);
            if (response.statusCode >= 200 && response.statusCode < 300) {
                resolve(body);
            } else {
                reject(response.statusCode);
            }
        }
    });
});