Update specific Values using Firebase for Android

Question

I have a Firebase data created as follows

tasks
-K1NRz9l5PU_0R8ltgXz
   Description: "test1"
   Status: "PENDING"
 -K1NRz9l5PU_0CFDtgXz
   Description: "test2"
   Status: "PENDING"

I need to update the 2nd object's status from PENDING to COMPLETED. I am using the updateChildren method but it is added a new node to the tasks child.

How do I update the status of the 2nd node without creating a new node?

Here is my code as of now,

//on a button click listener

  {

    Firebase m_objFireBaseRef = new Firebase(AppConstants.FIREBASE_URL);        
    final Firebase objRef = m_objFireBaseRef.child("tasks");    
    Map<String,Object> taskMap = new HashMap<String,Object>();
    taskMap.put("Status", "COMPLETED");
    objRef.updateChildren(taskMap); //should I use setValue()...?

 });

Answer 1

You're not specifying the task id of the task that you want to update.

String taskId = "-K1NRz9l5PU_0CFDtgXz";

Firebase m_objFireBaseRef = new Firebase(AppConstants.FIREBASE_URL);        
Firebase objRef = m_objFireBaseRef.child("tasks");
Firebase taskRef = objRef.child(taskId);
Map<String,Object> taskMap = new HashMap<String,Object>();
taskMap.put("Status", "COMPLETED");
taskRef.updateChildren(taskMap);

Alternatively, you can just call setValue() on the property you want to update

String taskId = "-K1NRz9l5PU_0CFDtgXz";

Firebase m_objFireBaseRef = new Firebase(AppConstants.FIREBASE_URL);        
Firebase objRef = m_objFireBaseRef.child("tasks");
Firebase taskRef = objRef.child(taskId);
Firebase statusRef = taskRef.child("Status");
statusRef.setValue("COMPLETED");

Or:

Firebase m_objFireBaseRef = new Firebase(AppConstants.FIREBASE_URL);        
Firebase objRef = m_objFireBaseRef.child("tasks");
objRef.child(taskId).child("Status").setValue("COMPLETED");

Update

Not sure what "I need to track the ID based on the status" means. But if you want to synchronize all tasks that are in status Pending, you'd do:

Firebase m_objFireBaseRef = new Firebase(AppConstants.FIREBASE_URL);        
Firebase objRef = m_objFireBaseRef.child("tasks");
Query pendingTasks = objRef.orderByChild("Status").equalTo("PENDING");
pendingTasks.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot tasksSnapshot) {
        for (DataSnapshot snapshot: tasksSnapshot.getChildren()) {
            snapshot.getRef().child("Status").setValue("COMPLETED");
        }
    }
    @Override
    public void onCancelled(FirebaseError firebaseError) {
        System.out.println("The read failed: " + firebaseError.getMessage());
    }
});

Answer 2

You can use code below to update

HashMap<String, Object> result = new HashMap<>();
        result.put("Description", "Your Description comes here");

FirebaseDatabase.getInstance().getReference().child("tasks").child("-K1NRz9l5PU_0R8ltgXz").updateChildren(result);

It will update a specific child