Question

在我的主要活动中，我通过在整个数据库中搜索用户ID（...created_at":"2016-11-01 14:19:07"},{"sub_items":["subOne","subTwo","subThree"...）来检查用户是否已注册到我的应用，但每次都是（即使用户ID已保存在数据库中），查询无法找到它。

user.getUid

这就是我的数据库的样子：

        mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user == null) {
                //User is signed out
                startActivity(intentlogin);
                Log.d(TAG, "onAuthStateChanged:signed_out");
                finish();
            } else {

                //User is signed in
                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
                //has user Username?
                String Userid = user.getUid();
                Query usernamequery = mRef.orderByChild("Userid").equalTo(Userid);
                usernamequery.addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot snapshot) {
                        if (snapshot.exists()) {

                            //should go here when user id in database
                            // TODO: handle the case where the data already exists
                            return;
                        }
                        else {

                            //This is where it always lands
                            // TODO: handle the case where the data does not yet exist
                            startActivity(intentusername);
                            finish();
                        }
                    }

Answer 1

请记住，即使您查询单个项目，查询也始终返回值列表。迭代这些值。

Query usernamequery = mRef.orderByChild("Userid").equalTo(Userid);
                    usernamequery.addListenerForSingleValueEvent(new ValueEventListener() {
                        @Override
                        public void onDataChange(DataSnapshot snapshot) {
                            if (snapshot != null && snapshot.getChildren != null) {

                                //Define a model class for user that contains UserId and Username
                                for(DataSnapshot child : snapshot.getChildren()) {

                                    Model model = child.getValue(Model.class);

                                    //now, get the UserId and username from the model class

                                model.getUserId();

                            }
                        }
                        else {

                            //This is where it always lands
                            // TODO: handle the case where the data does not yet exist
                            startActivity(intentusername);
                            finish();
                        }
                    }

无法找到孩子的孩子价值Firebase Android

1 个答案: