feat: wip: write pseudo cache example using .concat

Kaushik Gopal · Kaushik Gopal · commit 736b1ac26755 · 2015-04-22T22:51:19.000-07:00
diff --git a/README.md b/README.md
@@ -72,7 +72,7 @@ Have a look at the accompanying blog posts for details on this demo:
 2. [DebouncedBuffer used for the fancier variant of the demo](http://nerds.weddingpartyapp.com/tech/2014/12/24/secret-bonus-part-debouncedbuffer-used-in-rxbus-example/)
 3. [share/publish/refcount](http://nerds.weddingpartyapp.com/tech/2014/12/24/rxjava-share-publish-refcount-and-all-that-jazz/)
 
-### Form validation using combineLatest
+### Form validation - using [`.combineLatest`](http://reactivex.io/documentation/operators/combinelatest.html)
 
 Thanks to Dan Lew for giving me this idea in the [fragmented podcast - episode #5](http://fragmentedpodcast.com/episodes/4/) (around the 4:30 mark).
 
@@ -85,12 +85,17 @@ Note that the `Func3` function that checks for validity, kicks in only after ALL
 The value of this technique becomes more apparent when you have more number of input fields in a form. Handling it otherwise with a bunch of booleans makes the code cluttered and kind of difficult to follow. But using `.combineLatest` all that logic is concentrated in a nice compact block of code (I still use booleans but that was to make the example more readable).
 
 
+### Retrieve data first from a (pseudo) cache, then a network call - using [`.concat`](http://reactivex.io/documentation/operators/concat.html)
+
+Using concat, you can retrieve information from an observable first (presumably this one is fast like retrieveing from a disk cache) and show preliminary data to a user. Subsequently, when the longer running 2nd observable is complete (say a network call), you can update the results on the interface using the latest information.
+
+For the purposes of illustration i use an in-memory `List` (not an actual disk cache), but shoot out a real network call to the github api so it gives you a feel of how this can really be applied in production apps.
+
+
 ## Work in Progress:
 
 Examples that I would like to have here, but haven't found the time yet to flush out.
 
-### First retrieve from cached data, if no cache found make a network call if you can't find your data (concat) (wip)
-[Courtesy: gist](https://gist.github.com/adelnizamutdinov/7483969)
 
 ### Pagination (wip)
 
diff --git a/app/src/main/java/com/morihacky/android/rxjava/MainActivity.java b/app/src/main/java/com/morihacky/android/rxjava/MainActivity.java
@@ -20,7 +20,8 @@ protected void onCreate(Bundle savedInstanceState) {
 
     getSupportFragmentManager().beginTransaction()
         .addToBackStack(this.toString())
-        .replace(R.id.activity_main, new MainFragment(), this.toString())
+        //.replace(R.id.activity_main, new MainFragment(), this.toString())
+        .replace(R.id.activity_main, new PseudoCacheConcatFragment(), this.toString())
         .commit();
   }
 
diff --git a/app/src/main/java/com/morihacky/android/rxjava/PseudoCacheConcatFragment.java b/app/src/main/java/com/morihacky/android/rxjava/PseudoCacheConcatFragment.java
@@ -0,0 +1,34 @@
+package com.morihacky.android.rxjava;
+
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import butterknife.ButterKnife;
+import com.morihacky.android.rxjava.app.R;
+import rx.Subscription;
+
+public class PseudoCacheConcatFragment
+    extends Fragment {
+
+  private Subscription _subscription = null;
+
+  @Override
+  public View onCreateView(LayoutInflater inflater,
+                           @Nullable ViewGroup container,
+                           @Nullable Bundle savedInstanceState) {
+    View layout = inflater.inflate(R.layout.fragment_form_validation_comb_latest, container, false);
+    ButterKnife.inject(this, layout);
+    return layout;
+  }
+
+  @Override
+  public void onPause() {
+    super.onPause();
+    if (_subscription != null) {
+      _subscription.unsubscribe();
+    }
+  }
+}
diff --git a/app/src/main/res/layout/fragment_pseudo_cache_concat.xml b/app/src/main/res/layout/fragment_pseudo_cache_concat.xml
@@ -0,0 +1,7 @@
+<LinearLayout
+    android:orientation="vertical"
+    android:layout_height="match_parent"
+    android:layout_width="match_parent"
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    >
+</LinearLayout>

Original file line number	Diff line number	Diff line change
`@@ -20,7 +20,8 @@ protected void onCreate(Bundle savedInstanceState) {`
`20`	`20`
`21`	`21`	`getSupportFragmentManager().beginTransaction()`
`22`	`22`	`.addToBackStack(this.toString())`
`23`		`- .replace(R.id.activity_main, new MainFragment(), this.toString())`
	`23`	`+ //.replace(R.id.activity_main, new MainFragment(), this.toString())`
	`24`	`+ .replace(R.id.activity_main, new PseudoCacheConcatFragment(), this.toString())`
`24`	`25`	`.commit();`
`25`	`26`	`}`
`26`	`27`