CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
TheUnreal
TheUnreal

Reputation: 24472

Android Firebase list data from keys

I have a node that stores a list of project keys for each user.

The structure of my user_projectes is:

enter image description here

I have started to play with Firebase for Android and I ended up with this:

mFirebaseDatabaseReference.child("user_projects").child(mFirebaseUser.getUid())
        .addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot snapshot) {
                for (DataSnapshot projectSnapshot: snapshot.getChildren()) {
                    Log.e("Project","Project Key found: " + projectSnapshot.getKey());
                }
            }
            @Override
            public void onCancelled(DatabaseError firebaseError) {
                Log.e("Chat", "The read failed: " + firebaseError.getDetails());
            }
        });

Currently what I got are keys for the projects.

I have another node, projects, which stores the project data. The projects data are stored in my projects/$projectKey node.

I will also have to populate the project name and photoURL inside my ListView/GridView.

How I can retrieve the project data for each project key I got and add it to my listview?

Upvotes: 1

Views: 625

Answers (3)

John O'Reilly
John O'Reilly

Reputation: 10350

Unfortunately, as @rhari mentions, you do have to make another query....what I've found useful when doing "joins' like this with firebase is to use RxJava...could have something like following for example (which you could use then in your adapter to populate ListView/RecyclerView) 

public Observable<Project> getProjects(String userId) {
    return getProjectKeys(userId).flatMap(projectKey -> getProject(projectKey));
}

Where this falls down is where you want your list to dynamically update as projects are added....in that case you'll need version of listner that has onChildAdded/onChildRemoved etc and will need then to do lookup of project from those.

Upvotes: 2

rhari
rhari

Reputation: 1367

Just query the database again

mFirebaseDatabaseReference.child("user_projects").child(mFirebaseUser.getUid())
    .addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            for (DataSnapshot projectSnapshot: snapshot.getChildren()) {
                String key = projectSnapshot.getKey();                         
                mFirebaseDatabaseReference.child("projects").child(key)
               .addListenerForSingleValueEvent(new ValueEventListener() {
                   @Override
                   public void onDataChange(DataSnapshot snapshot1) {
                       Project p = snapshot1.getValue();
                   }
               }
        }
        @Override
        public void onCancelled(DatabaseError firebaseError) {
            Log.e("Chat", "The read failed: " + firebaseError.getDetails());
        }
    });

Upvotes: 2

Oussema Aroua
Oussema Aroua

Reputation: 5339

You have to create a model for your project entity then you can use Project mProject = projectSnapshot.getValue(Project.class);

Upvotes: 0

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