Firebase 2

Chat bot using Firebase (Read, write and database structure)
https://www.udacity.com/course/firebase-in-a-weekend-by-google-android--ud0352

Database Security Rules:

{
 "rules": {
   "chat" : {
     "messages" : {
       ".read": "auth != null",
       ".write": "auth != null"
     }
   },
   "special_chat" : {
     "messages": {
       ".read": 
       "root.child('users').child(auth.uid).child('paid').val() === true",
       ".write": 
       "root.child('users').child(auth.uid).child('paid').val() === true"
     }
   }
 }
}

Cascading Rules

When .read and .write rule permissions are evaluate to true, this cascades to all of the rule’s children. Only truth is cascading; falseness is not cascading.

Google Codelabs
https://codelabs.developers.google.com/codelabs/firebase-android/index.html?index=..%2F..%2Findex#2

How to get child of child value from firebase in android?

https://stackoverflow.com/questions/43293935/how-to-get-child-of-child-value-from-firebase-in-android?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa


Querying Data
https://stackoverflow.com/questions/39024702/firebase-querying-data

DatabaseReference reference = FirebaseDatabase.getInstance().getReference();

    Query query = reference.child("issue").orderByChild("id").equalTo(0);
    query.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {
                // dataSnapshot is the "issue" node with all children with id 0
                for (DataSnapshot issue : dataSnapshot.getChildren()) {
                    // do something with the individual "issues"
                }
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

For more reference:

https://stackoverflow.com/questions/30564735/android-firebase-simply-get-one-child-objects-data?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa




Basic information

https://firebase.google.com/docs/database/android/start/

https://firebase.googleblog.com/2016/11/what-happens-to-database-listeners-when-security-rules-reject-an-update.html




Material to learn Firebase

https://hackr.io/tutorials/learn-firebase