Return a string from onCall firebase cloud function

Question

I'm studying firebase cloud function and trying to register a user at firebase auth using javascript and the cloud functions. What I want to do is to send the data to the cloud function, return data from the cloud function, and then use it on the web app. How can I do it? Here are both codes:

Javascript sends values, which is working well:

const sendData = firebase.functions().httpsCallable('registerUser');
    sendData({
        email: userEmail,
        password: userPassword

    });

and here, my cloud function, which is registering the user correctly.

exports.registerUser = functions.https.onCall((data, context) => {
const userEmail = data.email;
const userPassword = data.password;

    admin.auth().createUser({
        email: userEmail,
        emailVerified: false,
        password: userPassword,
        displayName: "name",
        photoURL: "...", 
        disabled: false
    })
    .then(() => {
        //want to return messages if succeed or not

      }) });

I want to send the messages from the cloud function and then get it on my javascript code. How can I do it?

Answer 1

As explained in the documentation, to "send data back to the client, return data that can be JSON encoded" and to return errors you should "throw (or return a Promise rejected with) an instance of functions.https.HttpsError".

exports.registerUser = functions.https.onCall((data, context) => {
    const userEmail = data.email;
    const userPassword = data.password;

    return admin.auth().createUser({  // See the return here
        email: userEmail,
        emailVerified: false,
        password: userPassword,
        displayName: "name",
        photoURL: "...",
        disabled: false
    })
        .then(userRecord => {
            //want to return messages if succeed or not
            return {
                result: 'success'
            };
        })
        .catch(error => {
            throw new functions.https.HttpsError('invalid-argument', 'message');
        })
});

You may use different error codes, depending on the type of error. See the doc.

---

Then, in the client, you need to do as follows:

sendData({
    email: userEmail,
    password: userPassword
}).then(function(response) {
   // Read result of the Cloud Function.
   var result = response.data.result;
   // ...
 }).catch(function(error) {
   // Getting the Error details.
   var code = error.code;
   var message = error.message;
   var details = error.details;
   // ...
 });