实时数据库 orderbyByChild(timeStamp) 不工作 (android-java)

Question

这是我的数据结构

  "Posts" : {
"-MnL-M_t4hHrcaqWecDM" : {
  "description" : "",
  "picture" : "",
  "postKey" : "-MnL-M_t4hHrcaqWecDM",
  "timeStamp" : 1635677993574,
  "title" : "",
  "userId" : "",
  "userPhoto" : ""
},
"-MnL-xtVgZAC2TIY6Whn" : {
  "description" : "",
  "picture" : "",
  "postKey" : "",
  "timeStamp" : 1635678150450,
  "title" : "",
  "userId" : "",
  "userPhoto" : ""
},

我想删除具有旧时间戳的帖子。我使用 equalTo 方法而不是 endAt 来练习。所以我使用这个代码

private void beginDelete() {
    DatabaseReference db = FirebaseDatabase.getInstance().getReference();
    Query queryByTimestamp = db.child("Posts").orderByChild("timeStamp").equalTo("1635677993574");
    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 삭제안되었습니다.",Toast.LENGTH_SHORT).show();

            }
        }
    });

所以我使用查询在 Posts -> “-MnL-M_t4hHrcaqWecDM” -> “timeStamp”中指定“timeStamp” 像那样。但我认为“-MnL-M_t4hHrcaqWecDM”会造成问题。是否可以通过“-MnL-M_t4hHrcaqWecDM”子查询找到“timeStamp”？因为我可以使用 postKey 删除 Posts.. 喜欢这里

        StorageReference picRef = FirebaseStorage.getInstance().getReferenceFromUrl(postImage);
    picRef.delete()
            .addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                    //image deleted, now delete database
                    Query fquery =FirebaseDatabase.getInstance().getReference("Posts").orderByChild("postKey").equalTo("-MDFJ23...");
                    fquery.addListenerForSingleValueEvent(new ValueEventListener() {
                        @Override
                        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                            for (DataSnapshot ds:dataSnapshot.getChildren()){
                                ds.getRef().removeValue(); // remove values from firebase where postkey matches
                            }
                            //Deleted
                            Toast.makeText(PostDetailActivity.this,"게시글이 삭제되었습니다.",Toast.LENGTH_SHORT).show();
                        }

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

                        }
                    });

                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    //failed, can't go further
                    Toast.makeText(PostDetailActivity.this,""+e.getMessage(),Toast.LENGTH_SHORT).show();
                }
            });

这是完整的代码。

ImageView imgPost,imgUserPost,imgCurrentUser;
TextView txtPostDesc,txtPostDateName,txtPostTitle;
EditText editTextComment;
Button btnAddComment;
String PostKey;
FirebaseAuth firebaseAuth;
FirebaseUser firebaseUser;
FirebaseDatabase firebaseDatabase;
RecyclerView RvComment;
CommentAdapter commentAdapter;
List<Comment> listComment;
static String COMMENT_KEY = "Comment";
InputMethodManager imm;
EditText et;
Button btnDeletePost;
String myUid;
String UId;
String postImage;
private DatabaseReference mDatabase;







@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);


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

    myUid = FirebaseAuth.getInstance().getCurrentUser().getUid();

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

    // add Comment button click listner

    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("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());
                    }
                });

            }
            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
    // firt 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() {
    DatabaseReference db = FirebaseDatabase.getInstance().getReference();
    Query queryByTimestamp = db.child("Posts").orderByChild("timeStamp").equalTo("1635677993574");
    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 삭제안되었습니다.",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;


}

}

谢谢你回答我

Answer 1

您的timeStamp属性是一个数字，不是一个字符串。

"timeStamp" : 1635677993574

所以要解决这个问题，请更改以下查询：

Query queryByTimestamp = db.child("Posts").orderByChild("timeStamp").equalTo("1635677993574");

收件人：

Query queryByTimestamp = db.child("Posts").orderByChild("timeStamp").equalTo(1635677993574);

实际搜索数字而不是字符串。看，没有双引号？

实时数据库 orderbyByChild(timeStamp) 不工作 (android-java)

Realtime database orderbyByChild(timeStamp) not working (android-java)

java

android

timestamp

firebase-realtime-database