如何将数组从一个函数传递到另一个函数作为Cloud Function中的引用

Question

I have one function getUsers where I have one array jsonResponse . I am passing that array to computeData function. I want computeData function should be able to add items in jsonResponse array itself.

But below code is not adding in same array, as it always return empty array in response.send function.

index.js

exports.getUsers = functions.https.onRequest((request, response) => {
  var x = [];

  var xLocation,
    yLocation = [],
    jsonResponse = [];

  // print algorithm name
  console.log(request.query.algo);

  let geoFire = new GeoFire(db.ref("/users/" + request.query.userId));

  geoFire.get("location").then(function(location) {
    xLocation = location;
  });

  db
    .ref("/users/" + request.query.userId)
    .once("value")
    .then(function(snapshot) {
      var jsonObject = snapshot.val();
      var basicProfileJsonObject = jsonObject.basicProfile;
      for (var key in basicProfileJsonObject) {
        if (utils.isNumber(basicProfileJsonObject[key])) {
          x.push(basicProfileJsonObject[key]);
        }
      }
      db.ref("/users/").once("value").then(function(snapshot) {
        var y = [];
        snapshot.forEach(function(item) {
          var user = item.val();
          let userId = user.basicProfile.userId;
          if (userId !== request.query.userId) {
            if (xLocation == null) {
              computeData(x, user, request.query.algo, jsonResponse);
            } else {
              let geoFire = new GeoFire(db.ref("/users/" + userId));
              geoFire.get("location").then(function(location) {
                if (location === null) {
                  console.log(
                    "Provided key is not in GeoFire, will ignore profile"
                  );
                  computeData(x, user, request.query.algo, jsonResponse);
                } else {
                  console.log("Provided key has a location of " + location);
                  var distance = GeoFire.distance(xLocation, location); // in km
                  console.log("Distance: " + distance);

                  if (distance < 15) {
                    computeData(x, user, request.query.algo, jsonResponse);
                  }
                }
              });
            }
          }
        });
        response.send(jsonResponse);
      });
    });
});

function computeData(x, user, algo, jsonResponse) {
  var similarityCount,
    y = [];

  var basicProfileJsonObject = user.basicProfile;
  for (var key in basicProfileJsonObject) {
    if (utils.isNumber(basicProfileJsonObject[key])) {
      y.push(basicProfileJsonObject[key]);
    }
  }

  if (algo === "cosine") {
    // compute cosine value
    similarityCount = cosineUtils.cosineSimilarity(x, y);
  } else if (algo == "euclidean") {
    // compute euclidean distance value
    similarityCount = 1 / (1 + euclidean(x, y));
  } else if (algo === "pearson-correlation") {
    // compute pearson correlation coefficents
    similarityCount = pcorr.pearsonCorrelation(x, y);
  }
  console.log(x);
  console.log(y);
  console.log(similarityCount);
  jsonResponse.push(user);
}

Does anyone know how to pass array as reference and add items into it in Cloud Function for Firebase ?

Answer 1

Your else statement is a promise which means your loop would have finished and called response.send(jsonResponse); by the time it gets to computeData() in your else statement.

Try something like this, it doesn't touch all your variables but the main idea is to use Promise.all with computed values as resolved -

exports.getUsers = functions.https.onRequest((request, response) => {
  // blah blah
  var y = []; // store promises that resolves your computed value
  snapshot.forEach(function(item) {
    // blah blah
    if (xLocation == null) {
      y.push(Promise.resolve(computeData());
    } else {
      y.push(computeAnotherData(userId));
    }
  });

  Promise.all(y)
    .then(values => {
      response.send(values);
    });
});

function computeAnotherData(userId) {
  let geoFire = new GeoFire(db.ref("/users/" + userId));
  return geoFire.get("location").then(function(location) {
    return computeData();
  });
}

Hope it makes sense.