Firebase functions.https.onCall works but returns null

Question

I have the following firebase cloud function written in node.js that I call from my Android app

exports.findNearestBranch = functions.https.onCall((data, context) => { 
  var latitutde = data.lat;
  var longitude = data.long;

  var ret;

  return getLocationObject(latitutde,longitude)
    .then(function(result){
      var fromObject=result;
      console.log('CONTEXT CLIENT '+latitutde+' LONG '+longitude);

      calculateNearestBranch(fromObject)
        .then(function(result){
          console.log("TO APP "+JSON.stringify(result));
          ret=result;
        })
        .catch(function(error){

        });
    })
    .catch(function(error){

    });
});

The function works fine but I get null when trying to get results in Android with the following method

private Task<String> inputCurrentLocation(String[] geoLocations) { 
  Map<String, Object> data = new HashMap<>();
  data.put( "lat", geoLocations[0] );
  data.put( "long", geoLocations[1] );

  return mFunctions
    .getHttpsCallable( "findNearestBranch" )
    .call( data )
    .continueWith( new Continuation<HttpsCallableResult, String>() {
      @Override
      public String then(@NonNull Task<HttpsCallableResult> task) throws Exception {
        String result = (String) task.getResult().getData();
        return result;
      }
    } ).addOnCompleteListener( new OnCompleteListener<String>() {
      @Override
      public void onComplete(@NonNull Task<String> task) {
        String result = task.getResult();
        System.out.println("RESULT FROM NODE "+result+" SUCCESS"+task.isSuccessful());
      }
    } );
}

I have wasted countless hours online trying to find what is wrong with no success. Someone please point where my problem is.

Answer 1

You're not returning anything in your https callable.

Try adding a return to the calculateNearestBranch function and have that function return the result variable.

Also you should put some logging into the catch statements so your callable won't fail silently.

exports.findNearestBranch = functions.https.onCall((data, context) => { 
  var latitutde = data.lat;
  var longitude = data.long;

  return getLocationObject(latitutde,longitude)
    .then(function(result){
      var fromObject=result;
      console.log('CONTEXT CLIENT '+latitutde+' LONG '+longitude);

      // Added `return`
      return calculateNearestBranch(fromObject)
        .then(function(result){
          console.log("TO APP "+JSON.stringify(result));

          // Returned `result`
          return result;
        })
        .catch(function(error){

        });
    })
    .catch(function(error){

    });
});