Problem while using Firebase cloud functions in Unity: request data always empty

Question

I'm trying to run official quickstart example of Firebase Cloud Functions for Unity engine. The parameter data (dictionary of objects) passed when calling function from unity is always empty. I tried different Firebase SDK versions, but the problem is always there. I have no idea what the problem could be, please help.

Here is the code in Unity:

void Start()
{
        StartCoroutine(AddNumbers(7, 7));
}

protected IEnumerator AddNumbers(int firstNumber, int secondNumber) {
        var functions = FirebaseFunctions.GetInstance(FirebaseApp.DefaultInstance);
        var func = functions.GetHttpsCallableFromURL("https://getnumbers-dxhi3lnaew-uc.a.run.app");
        var data = new Dictionary<string, object>();
        data["firstNumber"] = firstNumber;
        data["secondNumber"] = secondNumber;
        var task = func.CallAsync(data).ContinueWithOnMainThread((callTask) => {
            if (callTask.IsFaulted) {
                // The function unexpectedly failed.
                Debug.Log("FAILED!");
                Debug.Log(String.Format("  Error: {0}", callTask.Exception));
                return;
            }

            // The function succeeded.
            var result = (IDictionary)callTask.Result.Data;
            Debug.Log(String.Format("AddNumbers: {0}", result["operationResult"]));
        });
        yield return new WaitUntil(() => task.IsCompleted);
}

Cloud function code:

'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

// Adds two numbers to each other.
exports.getNumbers = functions.https.onCall((data) => {
  // Numbers passed from the client.
  const firstNumber = data.firstNumber;
  const secondNumber = data.secondNumber;

  // Checking that attributes are present and are numbers.
  if (Number.isFinite(firstNumber) || !Number.isFinite(secondNumber)) {
    // Throwing an HttpsError so that the client gets the error details.
    throw new functions.https.HttpsError('invalid-argument', '!The function ' +
        'must be called with two arguments "firstNumber" and "secondNumber" ' +
        'which must both be numbers.');
  }

  // returning result.
  return {
    firstNumber: firstNumber,
    secondNumber: secondNumber,
    operator: '+',
    operationResult: firstNumber + secondNumber,
  };
});

Answer 1

The argument to the Cloud Function is actually the entire request object, and the data you pass in the C# code is in a data property in there.

So:

exports.getNumbers = functions.https.onCall((request) => {
  // Numbers passed from the client.
  const firstNumber = request.data.firstNumber;
  const secondNumber = request.data.secondNumber;
  ...

Also see the Firebase documentation on callable functions, which has example showing this.