Added section on creating a model class

Author: puf

README.md

@@ -31,9 +31,75 @@ After the project is synchronized, we're ready to start using Firebase functiona
 
 ### Creating a model class
 
+In your app, create a class that represents the data from Firebase that you want to show in the ListView.
 
+So say we have these chat messages in our Firebase database:
+
+![Chat messages in dashboard](doc-images/5-chat-messages-in-dashboard.png "Chat messages in dashboard")
+
+We can represent a chat message with this Java class:
+
+    public class ChatMessage {
+        String message;
+        String name;
+
+        public ChatMessage() {
+        }
+
+        public ChatMessage(String name, String message) {
+            this.message = message;
+            this.name = name;
+        }
+
+        public String getMessage() {
+            return message;
+        }
+
+        public String getName() {
+            return name;
+        }
+    }
+
+A few things to note here:
+
+ * the field have the exact same name as the properties in Firebase. This allows Firebase to automatically map the properties to these fields.
+ * there is a default (parameterless constructor) that is necessary for Firebase to be able to create a new instance of this class
+ * there is a convenience constructor that takes the member fields, so that we easily create a fully initialized `ChatMessage` in our app
+ * the `getMessage` and `getName` methods are so-called getters and follow a JavaBean pattern
+
+A little-known feature of Firebase for Android is that you can pass an instance of this `ChatMessage` class to `setValue()`:
+
+    Firebase ref = new Firebase("https://nanochat.firebaseio.com/");
+    ChatMessage msg = new ChatMessage("puf", "Hello FirebaseUI world!");
+    ref.push().setValue(msg);
+
+The Firebase Android client will read the values from the `msg` and write them into the properties of the new child in the database.
+
+Conversely, we can read a `ChatMessage` straight from a `DataSnapshot` in our event handlers:
+
+    ref.limitToLast(5).addValueEventListener(new ValueEventListener() {
+        @Override
+        public void onDataChange(DataSnapshot snapshot) {
+            for (DataSnapshot msgSnapshot: snapshot.getChildren()) {
+                ChatMessage msg = msgSnapshot.getValue(ChatMessage.class);
+                Log.i("Chat", chat.getName()+": "+chat.getMessage());
+            }
+        }
+        @Override
+        public void onCancelled(FirebaseError firebaseError) {
+            Log.e("Chat", "The read failed: " + firebaseError.getMessage());
+        }
+    });
+
+In the above snippet we have a query for the last 5 chat messages. Whenever those change (i.e. when an new message is added)
+we get the `ChatMessage` objects from the `DataSnapshot` with `getValue(ChatMessage.class)`. The Firebase Android client will
+then read the properties that it got from the database and map them to the fields of our `ChatMessage` class.
+
+But when we build our app using the `FirebaseListAdapter`, we often won't need to register our own EventListener. The
+`FirebaseListAdapter` takes care of that for us.
 
 ### Subclassing the FirebaseListAdapter
 
 
+
 ## Contributing to the library

library/src/main/java/com/firebase/ui/FirebaseRecyclerViewAdapter.java

@@ -5,6 +5,7 @@
 
 import com.firebase.client.ChildEventListener;
 import com.firebase.client.DataSnapshot;
+import com.firebase.client.Firebase;
 import com.firebase.client.FirebaseError;
 import com.firebase.client.Query;
 
@@ -36,7 +37,6 @@ public FirebaseRecyclerViewAdapter(Query ref, Class<T> modelClass) {
         mModelClass = modelClass;
         mSnapshots = new FirebaseArray(ref);
 
-        // TODO: implement separate notifications for added, removed, changed and moved
         mSnapshots.setOnChangedListener(new FirebaseArray.OnChangedListener() {
             @Override
             public void onChanged(EventType type, int index, int oldIndex) {
@@ -74,6 +74,8 @@ public T getItem(int position) {
         return mSnapshots.getItem(position).getValue(mModelClass);
     }
 
+    public Firebase getRef(int position) { return mSnapshots.getItem(position).getRef(); }
+
     @Override
     public long getItemId(int position) {
         // http://stackoverflow.com/questions/5100071/whats-the-purpose-of-item-ids-in-android-listview-adapter