I'm using Firebase Realtime Database for storing and retrieving data for my Android application. In my activity I retrieve all data (example: list of user data) from Firebase using a childEventListener
.
I want to show a progress bar as long as the data is not completely retrieved from the database. How do I check if all data is completely retrieved so that I can close the progress bar after the data is loaded?
To see your current Realtime Database connections and data usage, check the Usage tab in the Firebase console. You can check usage over the current billing period, the last 30 days, or the last 24 hours.
Firebase data is retrieved by either a one time call to GetValueAsync() or attaching to an event on a FirebaseDatabase reference. The event listener is called once for the initial state of the data and again anytime the data changes.
Go to firebase console click on the 3 dots on right, click on import JSON, choose the newly created JSON file and it will delete all data from the firebase database.
The limit you're referring to is the limit for the number of concurrently connected users to Firebase Realtime Database on the free Spark plan. Once you upgrade to a payment plan, your project will allow 200,000 simultaneously connected users.
There is a common way to detect when Firebase is done synchronizing the initial data on a given location. This approach makes use of one of the Firebase event guarantees:
Value events are always triggered last and are guaranteed to contain updates from any other events which occurred before that snapshot was taken.
So if you have both a ValueEventListener
and a ChildEventListener
on a given location, the ValueEventListener.onDataChange()
is guaranteed to be called after all the onChildAdded()
calls have happened. You can use this to know when the initial data loading is done:
ref.addListenerForSingleValueEvent(new ValueEventListener() { public void onDataChange(DataSnapshot dataSnapshot) { System.out.println("We're done loading the initial "+dataSnapshot.getChildrenCount()+" items"); } public void onCancelled(FirebaseError firebaseError) { } }); ref.addChildEventListener(new ChildEventListener() { public void onChildAdded(DataSnapshot dataSnapshot, String previousKey) { System.out.println("Add "+dataSnapshot.getKey()+" to UI after "+previousKey); } public void onChildChanged(DataSnapshot dataSnapshot, String s) { } public void onChildRemoved(DataSnapshot dataSnapshot) { } public void onChildMoved(DataSnapshot dataSnapshot, String s) { } public void onCancelled(FirebaseError firebaseError) { } });
In my test run this results in:
Add -K2WLjgH0es40OGWp6Ln to UI after null Add -K2YyDkM4lUotI12OnOs to UI after -K2WLjgH0es40OGWp6Ln Add -K2YyG4ScQMuRDoFogA9 to UI after -K2YyDkM4lUotI12OnOs ... Add -K4BPqs_cdj5SwARoluP to UI after -K4A0zkyITWOrxI9-2On Add -K4BaozoJDUsDP_X2sUu to UI after -K4BPqs_cdj5SwARoluP Add -K4uCQDYR0k05Xqyj6jI to UI after -K4BaozoJDUsDP_X2sUu We're done loading the initial 121 items
So you could use the onDataChanged()
event to hide the progress bar.
But one thing to keep in mind: Firebase doesn't just load data. It continuously synchronizes data from the server to all connected clients. As such, there is not really any moment where the data is completely retrieved.
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