我在访问子节点时遇到问题。（firebase 实时数据库 - 增量报告）

Question

这是我的数据结构。

"Posts" : {
  "-MpVVpVIqmn0Iu78hDRp" : {
    "description" : "",
    "picture" : "",
    "postKey" : "",
    "reports" : 0,
    "timeStamp" : 1638001760487,
    "title" : "",
    "userId" : "",
    "userPhoto" : ""
  },
  "-MpVcioadtvRBRaa0n96" : {
    "description" : "",
    "picture" : "",
    "postKey" : "",
    "reports" : 0,
    "timeStamp" : 1638003830234,
    "title" : "",
    "userId" : "",
    "userPhoto" : ""
  },

我想访问“报告”部分。所以我用

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("Posts").child("reports").setValue(1);

但它会在不低于“-MpVVpVIqmn0Iu78hDRp”的帖子下方创建报告值 1。我想增加报告。但我不知道如何处理报告节点。

这是我的完整代码

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_post_detail);
    imm = (InputMethodManager)getSystemService(INPUT_METHOD_SERVICE);
    et = (EditText)findViewById(R.id.post_detail_comment);



    // let's set the statue bar to transparent


    // ini Views
    RvComment = findViewById(R.id.rv_comment);
    imgPost =findViewById(R.id.post_detail_img);
    imgUserPost = findViewById(R.id.post_detail_user_img);
    imgCurrentUser = findViewById(R.id.post_detail_currentuser_img);

    txtPostTitle = findViewById(R.id.post_detail_title);
    txtPostDesc = findViewById(R.id.post_detail_desc);
    txtPostDateName = findViewById(R.id.post_detail_date_name);

    editTextComment = findViewById(R.id.post_detail_comment);
    btnAddComment = findViewById(R.id.post_detail_add_comment_btn);
    btnDeletePost = findViewById(R.id.button_delete);
    btnnoti = findViewById(R.id.button_noti);
    btncommentnoti = findViewById(R.id.comment_noti);


    firebaseAuth = FirebaseAuth.getInstance();
    firebaseUser = firebaseAuth.getCurrentUser();
    firebaseDatabase = FirebaseDatabase.getInstance();
    // add post delete button
    mDatabase= FirebaseDatabase.getInstance().getReference();

    myUid = FirebaseAuth.getInstance().getCurrentUser().getUid();
    //게시글 신고기능
    btnnoti.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
            rootRef.child("Posts").child("reports").setValue(1);

        }
    });

    btnDeletePost.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //여기 수정 주의 UId.equals(myUid)
            if (true){
                Toast.makeText(PostDetailActivity.this,"삭제중...",Toast.LENGTH_SHORT).show();
                beginDelete();
                onBackPressed();
            }

        }
    });

    // add Comment button click listener

    btnAddComment.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            btnAddComment.setVisibility(View.INVISIBLE);
            DatabaseReference commentReference = firebaseDatabase.getReference(COMMENT_KEY).child(PostKey).push();
            String comment_content = editTextComment.getText().toString();
            String uid = firebaseUser.getUid();
            String uname = firebaseUser.getDisplayName();
            if (firebaseUser.getPhotoUrl()!=null){
                String uimg = firebaseUser.getPhotoUrl().toString();
                Comment comment = new Comment(comment_content,uid,uimg,uname);
                commentReference.setValue(comment).addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        showMessage("댓글이 등록되었습니다.");
                        editTextComment.setText("");
                        btnAddComment.setVisibility(View.VISIBLE);
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        showMessage("fail to add comment : "+e.getMessage());
                    }
                });

            }
            else{
                String usphoto =Integer.toString(R.drawable.userphoto);
                Comment comment = new Comment(comment_content,uid,usphoto,uname);
                commentReference.setValue(comment).addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        showMessage("comment added");
                        editTextComment.setText("");
                        btnAddComment.setVisibility(View.VISIBLE);
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        showMessage("fail to add comment : "+e.getMessage());
                    }
                });
            }




        }
    });


    // now we need to bind all data into those views
    // first we need to get post data
    // we need to send post detail data to this activity first ...
    // now we can get post data



    // 게시글 사진 백지 케이스
    postImage = getIntent().getExtras().getString("postImage") ;
    if(postImage!=null){
        Glide.with(this).load(postImage).into(imgPost);
    }
    else{
        Glide.with(this).load(R.drawable.whitepaper).into(imgPost);
    }


    String postTitle = getIntent().getExtras().getString("title");
    txtPostTitle.setText(postTitle);

    String userpostImage = getIntent().getExtras().getString("userPhoto");
    if (userpostImage!=null){
        Glide.with(this).load(userpostImage).into(imgUserPost);
    }
    else {
        Glide.with(this).load(R.drawable.userphoto).into(imgUserPost);
    }

    String postDescription = getIntent().getExtras().getString("description");
    txtPostDesc.setText(postDescription);

    // set comment user image
    if (firebaseUser.getPhotoUrl()!=null){
        Glide.with(this).load(firebaseUser.getPhotoUrl()).into(imgCurrentUser);
    }
    else{
        Glide.with(this).load(R.drawable.userphoto).into(imgCurrentUser);
    }
    // get post key
    PostKey = getIntent().getExtras().getString("postKey");

    String date = timestampToString(getIntent().getExtras().getLong("postDate"));
    txtPostDateName.setText(date);
    // get post uid
    UId = getIntent().getExtras().getString("userId");



    // ini Recyclerview Comment
    iniRvComment();


}

private void beginDelete() {


    //서버 관리용 개발자 옵션
    if (myUid.equals("k1kn0JF5idhrMzuw46GarEIBgPw2")) {

        long tlong = System.currentTimeMillis(); long ttime;
        ttime = tlong - 3*24*60*60*1000;
        DatabaseReference db = FirebaseDatabase.getInstance().getReference();
        Query queryByTimestamp = db.child("Posts").orderByChild("timeStamp").endAt(ttime);
        queryByTimestamp.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DataSnapshot> task) {
                if (task.isSuccessful()) {
                    for (DataSnapshot ds : task.getResult().getChildren()) {
                        ds.getRef().removeValue();
                        Toast.makeText(PostDetailActivity.this,"게시글이 삭제되었습니다.",Toast.LENGTH_SHORT).show();
                    }
                } else {
                    Log.d("TAG", task.getException().getMessage());
                    Toast.makeText(PostDetailActivity.this,"게시글이 삭제되지않았습니다.",Toast.LENGTH_SHORT).show();

                }
            }
        });

    }
    else if (UId.equals(myUid)) {
        DatabaseReference db = FirebaseDatabase.getInstance().getReference();
        Query queryByTimestamp = db.child("Posts").orderByChild("postKey").equalTo(PostKey);
        queryByTimestamp.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DataSnapshot> task) {
                if (task.isSuccessful()) {
                    for (DataSnapshot ds : task.getResult().getChildren()) {
                        ds.getRef().removeValue();
                        Toast.makeText(PostDetailActivity.this, "게시글이 삭제되었습니다.", Toast.LENGTH_SHORT).show();
                    }
                } else {
                    Log.d("TAG", task.getException().getMessage());
                    Toast.makeText(PostDetailActivity.this, "게시글이 삭제되지않았습니다.", Toast.LENGTH_SHORT).show();

                }
            }
        });
    }
    else{
        Toast.makeText(PostDetailActivity.this,"다른 사용자의 게시글입니다.",Toast.LENGTH_SHORT).show();
    }

}

public void linearOnClick(View v) {
    imm.hideSoftInputFromWindow(et.getWindowToken(), 0);
}


private void iniRvComment() {

    RvComment.setLayoutManager(new LinearLayoutManager(this));

    DatabaseReference commentRef = firebaseDatabase.getReference(COMMENT_KEY).child(PostKey);
    commentRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            listComment = new ArrayList<>();
            for (DataSnapshot snap:dataSnapshot.getChildren()) {

                Comment comment = snap.getValue(Comment.class);
                listComment.add(comment) ;

            }

            commentAdapter = new CommentAdapter(getApplicationContext(),listComment);
            RvComment.setAdapter(commentAdapter);


        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });




}

private void showMessage(String message) {

    Toast.makeText(this,message,Toast.LENGTH_LONG).show();

}


private String timestampToString(long time) {

    Calendar calendar = Calendar.getInstance(Locale.ENGLISH);
    calendar.setTimeInMillis(time);
    String date = DateFormat.format("yyyy-MM-dd",calendar).toString();
    return date;


}

}

这是我问题的一部分

btnnoti.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
            rootRef.child("Posts").child("reports").setValue(1);

        }
    });

我也试过 orderbychild，但我认为这不是正确的代码。

Answer 1

此代码：

rootRef.child("Posts").child("reports").setValue(1);

您是在告诉数据库将 /Posts/reports 的值设置为 1，这正是它随后所做的。

如果你想增加一个节点的当前值，你可以use the atomic increment operation:

rootRef.child("Posts").child("reports").setValue(ServerValue.increment(1));

如果您想增加 Posts 下特定节点的 reports 属性，您需要知道该节点的密钥。例如：

rootRef.child("Posts/-MpVVpVIqmn0Iu78hDRp/reports").setValue(ServerValue.increment(1));

如果您不知道要增加的节点的键，但确实知道一些其他唯一（足够）标识要更新的节点的值，您可以use a query找到钥匙。

例如，要更新具有特定 postKey 的所有节点：

Query query = rootRef.child("Posts").orderByChild("postKey").equalTo("thePostKeyValue");
query.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot postSnapshot: dataSnapshot.getChildren()) {
            postSnapshot.getReference().child("reports").setValue(ServerValue.increment(1));
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        throw databaseError.toException();
    }
}

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