为什么我的 firestore 函数向我的应用程序返回 null？

Question

I'm trying to figure aout, why my firestore function is always returning null. Here is my firestore function:

exports.isUserOnListFunction = functions.https.onCall(async (data, context) => {
    const userID = context.auth.uid;
    const userEmail = context.auth.token.email;
    const atIndex = userEmail.indexOf('@');
    const dotIndex = userEmail.indexOf('.');
    var userName = userEmail.slice(0, dotIndex);
    var userSurname = userEmail.slice(dotIndex+1, atIndex);
    userName = capitalizeFirstLetter(userName);
    userSurname = capitalizeFirstLetter(userSurname);
    return db.collection('allowed_users')
        .where("name", "==", userName)
        .where("surname", "==", userSurname)
        .get().then(snap => {
            if (!snap.empty) {
                db.collection("users").doc(userID).update({
                    onList: true
                });
                return {onList : true};
            }
        }).catch(()=>{
            console.log("Some error!")
        })

});

and here is my android (java) function calling firestore function:

    private Task<String> isUserOnList(){
    return mFunctions
            .getHttpsCallable("isUserOnListFunction")
            .call()
            .continueWith(new Continuation<HttpsCallableResult, String>() {
                @Override
                public String then(@NonNull Task<HttpsCallableResult> task) throws Exception {
                    String result = (String) task.getResult().getData();
                    System.out.println(result);
                    return result;
                 }
            });
}

Could someone please tell me what im doing wrong?

Answer 1

According to this doc

If returned is JS object with keys and values, which I suppose it is in this situation, getData() returns Map object.

I think task.getResult().getData().toString() method should be used to convert it (instead of (String) task.getResult().getData(); )

I would expect exception thrown, but maybe you have caught it in other parts of code not posted here.

Hope this will helps you.