如何从android RealTimeDatabase中获取Firebase的数据，根据regid进行更新

Question

我想从我的实时数据库服务器检索数据 这样我就可以根据我为用户保存的 reg-id（将其存储为子字符串，而不是 Auth）更新值。

到目前为止我已经这样做了

    private void updateDatatoFirebase(String regid, String doctor_name, String city,String speciality) {
    Map<String, Object> update=new HashMap<>();
    update.put("doctor",doctor_name);
    update.put("city",city);
    update.put("speciality",speciality);

    DatabaseReference dbref=FirebaseDatabase.getInstance().getReference();
    dbref.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            
            for (DataSnapshot ds : snapshot.getChildren()){
                key = snapshot.getKey();


                if(checkid.equalsIgnoreCase(regid))
                {
                    dbref.updateChildren(update);
                    Toast.makeText(need_help.this, "Data in Database updated", Toast.LENGTH_SHORT).show();
                }

                else
                    Toast.makeText(need_help.this, "No such id found", Toast.LENGTH_SHORT).show();
               
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {
           
            Toast.makeText(need_help.this, "Fail to add data " + error, Toast.LENGTH_SHORT).show();
        }
    });
}

更新但不会更新我已经保存了这样的数据

private void addDatatoFirebase(String regid, String doctor_name, String city,String speciality) {
    
    root=firebaseDatabase.getReference().child("RegId").child(regid);
    HashMap<String, String> usermap=new HashMap<>();
    usermap.put("doctor",doctor_name);
    usermap.put("city",city);
    usermap.put("speciality",speciality);
    root.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
           
            root.push().setValue(usermap);

            
            Toast.makeText(need_help.this, "Data in Database updated", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {
          
            Toast.makeText(need_help.this, "Fail to add data " + error, Toast.LENGTH_SHORT).show();
        }
    });

Answer 1

为了能够更新特定节点下的所有子节点，例如1234 ，您必须将1234作为第一个参数传递给以下方法：

private void updateDatatoFirebase(String regid, String doctor_name, String city,String speciality) {
    Map<String, Object> update=new HashMap<>();
    update.put("doctor",doctor_name);
    update.put("city",city);
    update.put("speciality",speciality);

    DatabaseReference dbref=FirebaseDatabase.getInstance().getReference();
    dbref.child("RegId").child(regid).addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            for (DataSnapshot ds : snapshot.getChildren()){
                ds.getRef().updateChildren(update).addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        if (task.isSuccessful()) {
                            Toast.makeText(need_help.this, "Data in Database updated", Toast.LENGTH_SHORT).show();
                        } else {
                            Toast.makeText(need_help.this, "Failed with an error: " + task.getException().getMessage(), Toast.LENGTH_SHORT).show();
                        }
                    }
                });
                
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {
            Toast.makeText(need_help.this, "Fail to add data " + error, Toast.LENGTH_SHORT).show();
        }
    });
}

注意事项：

• 我在根引用之后添加了两个额外的调用.child("RegId")和.child(regid)调用。
• 我已经使用ds调用getRef()然后.updateChildren(update) 。
• 我附上了一个监听器，以查看在更新1234以下的子项时是否出现问题。