Uidの特定のキーを取得してクエリFirebaseに使用します。

Question

特定のノードのキーの値を使用してFirebaseクエリを作成しようとしています。特定のノードが現在サインインしているユーザーです。

現在ログインしているユーザーのノードの下にある特定のキーの値を取得し、データベースに照会するにはどうすればよいですか？

これは私のコードです：

final String user_id = firebaseAuth.getCurrentUser().getUid(); 

    databaseReference.addValueEventListener(new ValueEventListener() { 
     @Override 
     public void onDataChange(DataSnapshot dataSnapshot){ 
      halls1 = (String) dataSnapshot.child("Male").child(user_id).getValue(User.class).getHalls(); 
      halls2 = (String) dataSnapshot.child("Female").child(user_id).getValue(User.class).getHalls(); 
     } 
     @Override 
     public void onCancelled(DatabaseError databaseError){ 

     } 
    }); 


    databaseReference.addValueEventListener(new ValueEventListener() { 
     @Override 
     public void onDataChange(DataSnapshot dataSnapshot) { 
      if(dataSnapshot.child("Male").hasChild(user_id)){ 
       query = databaseReference.child("Female").orderByChild("halls").equalTo(halls1); 

      } 
      else{ 
       query = databaseReference.child("Female").orderByChild("halls").equalTo(halls2); 
      } 
     } 
     @Override 
     public void onCancelled(DatabaseError databaseError){ 

     } 
    }); 

データベース構造

{ 
    "Users" : { 
    "Female" : { 
     "WwBjblOo8maSP5PXlYviONrS3Oo2" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2Fecf2758a-5628-4297-bcb3-e8c3f138cbbd.jpeg?alt=media&token=1ca6067d-6c08-49b9-a2bf-6a8315ada067", 
     "halls" : "Kwapong", 
     "levels" : "300", 
     "username" : "merylstre" 
     }, 
     "X8c80zaY0kfT5KVoTFHbhPIEG9z2" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F51dc26a1-45e8-4897-9c2f-14caf8e79cc5.jpeg?alt=media&token=90818c1e-167e-4799-bc29-b3fe52529cd2", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "hashcodef" 
     } 
    }, 
    "Male" : { 
     "2EXejmHoMlWoKSDb5APvSt8do5e2" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F83ca18a0-63a5-477a-ab1e-b2732b3ebfa1.jpeg?alt=media&token=b8626221-a67c-48e3-b958-d373c9f63c69", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "fillman" 
     }, 
     "BW79oGosAIhdxDxYXbtHbSbC0D23" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F90b93b19-230b-4f28-b394-358d0c516c5c.jpeg?alt=media&token=0c82c272-d6fb-46e8-a6cf-581f5501de7b", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "radjames" 
     }, 
     "Mop4hbS0zne6QS3woum1udLgwqf1" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F78621a8b-7d67-413c-9e57-f378e60ba41e.jpeg?alt=media&token=3982ee0a-2a34-41b3-9250-f0884531ee86", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "radjohn" 
     }, 
     "VvnOY3k7Cwa36bJW55JiZDJRwPN2" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F1ac7080f-8db8-49a7-bb76-34b007deb839.jpeg?alt=media&token=6d100527-80d3-49b3-b0ae-617dd55e64de", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "ciryadams" 
     }, 
     "WOT11DVkoVb9owzK4qKHbvT4ODF2" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F3fda02ae-c577-4a4a-86c1-cadcaf518c97.jpeg?alt=media&token=5baf2a79-b14c-4e28-b7bb-77e55ae08e55", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "markzuck" 
     }, 
     "dbnmFoC4hnSCsXsxJgVO0Q7GYx13" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F2366c787-fb16-4049-9c7d-3d0c2a09ab9b.jpeg?alt=media&token=25bda8dd-ab24-4b9b-8299-534e49bf9ed4", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "dasdsada" 
     }, 
     "iqZfSgGNpPZ4HDtOUuHYZ1u8x273" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2Fc52cd467-05b9-4ece-8085-4cdf502839c5.jpeg?alt=media&token=4c9eb36e-4644-49ec-85eb-c2fef38ca50e", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "maameEsi" 
     }, 
     "jj9yycmDNbZwiPVTLrRyYZheM702" : { 
     "downloadUrl" : "https://firebasestorage.googleapis.com/v0/b/loginapp-8088d.appspot.com/o/userProfiles%2F5c4a34b2-bc7b-43e7-8b00-7e0bf63ff252.jpeg?alt=media&token=59a11905-a67d-48ea-9f16-10ffd3915876", 
     "halls" : "Sarbah", 
     "levels" : "100", 
     "username" : "hashcode" 
     } 
    } 
    } 
} 

Answer 1

彼らはMaleノードの下にいる場合には、ユーザを読むには：

final String user_id = firebaseAuth.getCurrentUser().getUid(); 
final DatabaseReference root = FirebaseDatabase.getInstance().getReference(); 
DatabaseReference userRef = root.child("Male").child(user_id); 

userRef.addValueEventListener(new ValueEventListener() { 
    @Override 
    public void onDataChange(DataSnapshot dataSnapshot){ 
     if (snapshot.exists()) { 
      halls1 = (String) snapshot.getValue(User.class).getHalls(); 
     } 
     else { 
      System.out.println("User "+user_id+" does not exist under /Male"); 
     } 

    } 
    @Override 
    public void onCancelled(DatabaseError databaseError){ 

    } 
});