如何在 Firebase 实时数据库中的特定子树中推送值

Question

I am trying to upload a url with a name to a specific tree child in Firebase Database.

Code :

public void UploadData(View view){

        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        intent.setType("image/gif");
        startActivityForResult(intent,ImageBack);

protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        Folder = FirebaseStorage.getInstance().getReference().child("ImageFolder");
        AutoCompleteTextView textView = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView2);
        source2 = textView.getText().toString();

        if(requestCode == SELECT_VIDEO){
            if(resultCode == RESULT_OK){
                Uri ImageData = data.getData();

                final StorageReference Imagename = Folder.child("image" + ImageData.getLastPathSegment());

          Imagename.putFile(ImageData).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

               //         Toast.makeText(realupload.this, "Uploaded", Toast.LENGTH_SHORT).show();

                        Imagename.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                            @Override
                            public void onSuccess(Uri uri) {

                DatabaseReference imageStore = FirebaseDatabase.getInstance().getReference().child("main");
                                HashMap<String,String> hashMap = new HashMap<>();
                                hashMap.put(source2, String.valueOf(uri));

              imageStore.setValue(hashMap).addOnSuccessListener(new OnSuccessListener<Void>() {
                                    @Override
                                    public void onSuccess(Void aVoid) {
                             Toast.makeText(realupload.this, "Finally Completed", Toast.LENGTH_SHORT).show();
                                    }
                                });

                            }
                        });
                    }
                });
            }
        }
    }

The child tree "main" is the child tree that I want to add values to.

Currently when I use this, it will override my all my values in my "main" child tree in Firebase Database. How do I change this so that it doesn't override my "main" child tree, but just add another name with value under it.

Answer 1

How do I change this so that it doesn't override my "main" child tree, but just add another name with value under it.

You can use the updateChildren() method:

    Map<String, Object> childUpdates = new HashMap<>();
    childUpdates.put("food","all" );
        mDatabase.updateChildren(childUpdates);

More information here:

https://firebase.google.com/docs/database/android/read-and-write#update_specific_fields

Answer 2

simply you just need to update value. for update value use this code imageStore. updateChildren(hashMap) imageStore. updateChildren(hashMap) to update value

Or You can replace below code.

public void UploadData(View view){

        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        intent.setType("image/gif");
        startActivityForResult(intent,ImageBack);

protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        Folder = FirebaseStorage.getInstance().getReference().child("ImageFolder");
        AutoCompleteTextView textView = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView2);
        source2 = textView.getText().toString();

        if(requestCode == SELECT_VIDEO){
            if(resultCode == RESULT_OK){
                Uri ImageData = data.getData();

                final StorageReference Imagename = Folder.child("image" + ImageData.getLastPathSegment());

          Imagename.putFile(ImageData).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

               //         Toast.makeText(realupload.this, "Uploaded", Toast.LENGTH_SHORT).show();

                        Imagename.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                            @Override
                            public void onSuccess(Uri uri) {

                DatabaseReference imageStore = FirebaseDatabase.getInstance().getReference().child("main");
                                HashMap<String,String> hashMap = new HashMap<>();
                                hashMap.put(source2, String.valueOf(uri));

              imageStore. updateChildren(hashMap).addOnSuccessListener(new OnSuccessListener<Void>() {
                                    @Override
                                    public void onSuccess(Void aVoid) {
                             Toast.makeText(realupload.this, "Finally Completed", Toast.LENGTH_SHORT).show();
                                    }
                                });

                            }
                        });
                    }
                });
            }
        }
    }

for more information https://stackoverflow.com/a/41296760/9315408

Answer 3

You need to find a specif key to update.

ie imageStore.child("cinta").setValue("value")