Call API in content provider for global search

Question

We are attempting to hook up our AndroidTV app to append results into the global search. I'm running into an issue where I cannot make an api call to get the results because the system calls my content provider on the main thread.

@Override
public Cursor query(Uri uri, String[] projection, String search, String[] selectionArgs, String searchOrder) {

    ... Logic here that calls the API using RxJava / Retrofit

    return cursor;
}


<searchable xmlns:android="http://schemas.android.com/apk/res/android"
android:label="@string/foo"
android:searchSettingsDescription="@string/foo_results"
android:includeInGlobalSearch="true"
android:searchSuggestAuthority="com.foo.search.provider"
android:searchSuggestIntentAction="android.intent.action.VIEW" />

<provider
   android:authorities="com.foo.search.provider"
   android:name=".search.GlobalSearchProvider"
   android:exported="true"/>

When i do a global search i can see that the ContentProvider#query is called. If i attempt to do an api call on the current thread i get an networkonmainthreadexception.

I have attempted to notifty the cursor that data has changed via but had no success either.

getContext().getContentResolver().notifyChange(Uri.parse("content://com.foo.test"), null);
...
cursor.setNotificationUri(getContext().getContentResolver(), Uri.parse("content://com.foo.test"));

Is there anyway i can force the O.S to call the content provider on a seperate thread or at least notify the search that the cursor has new content?

Thank You

Answer 1

One of the solutions can be to set the content provider process

android:process:":androidtv"

and set the ThreadPolicy to LAX just before making network call

ThreadPolicy tp = ThreadPolicy.LAX;
StrictMode.setThreadPolicy(tp);

By running contentprovider in a different process, even if the query runs on main thread, it will not affect your UI operations

Answer 2

I've also struggled with this as I didn't find the currently accepted answer of blocking the UI acceptable.

However, according to Marc Bächinger from the Google TV team, this is only a problem with the emulator. In more recent builds (such as those in the currently available hardware) the search providers are called in a background thread, which avoid the problem altogether.

I've been able to test it on the Nexus Player and can confirm it works properly.

Source: https://plus.google.com/+DanielCachapa/posts/dbNMoyoRGEi

Answer 3

EDITED ANSWER

I've experienced this issue myself and I had to rely on the accepted answer's proposed solution. However, I've noticed that there is a noticeable lag when typing in the 'Global search' box. This lag is:

1. Caused by the application, since its removal makes the lag disappear
2. Most likely due to a synchronous wait on the queried applications - since our app does two network requests, the query() method takes time to complete, resulting in this lag

I found out that the separate process (:androidtv) is not necessary. By setting the ThreadPolicy.LAX configuration, the network request will still execute without throwing a NetworkOnMainThreadException.

I still don't understand why the lag is there.

---

ORIGINAL ANSWER

I don't believe that the accepted answer, while it certainly works, is the right way do it.

Once the query() method is called, you should spawn a new thread/task/job to perform a network call (therefore, avoiding the NetworkOnMainThreadException), which will update the adapter once it obtains the desired data.

There are different ways of doing this. You can either use a callback or an event bus (e.g., Otto). This is the method that I call to update the adapter:

public void updateSearchResult(ArrayList<Data> result) {
    mListRowAdapter.clear();
    mListRowAdapter.addAll(0, result);
    HeaderItem header = new HeaderItem(0, "Search results", null);
    mRowsAdapter.add(new ListRow(header, mListRowAdapter));
}

Answer 4

In order to solve for displaying the result in the global search using API in query method what I basically did is introduce a delay between fetching of api result and querying the db for results to return a cursor.

You can do this via

private Cursor getSuggestions(final String query) {
    Cursor cursor;
    cursor = getCursor(query);
    if (cursor==null || cursor.getCount() == 0) {
    //apiCall
      try {
        Thread.sleep(X millis);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
      cursor = getCursor(query);
    }
    return cursor;
  }

Will keep on looking to see if, we can get some kind of hook to reattach without using a delay.

Answer 5

Because I wasn't really familiar with the Android thread. For anyone who has the same problem as me. The main point is that the query() method in content provider is not running on the UI thread.

Instead of using the asynchronous function to do HTTP requests and then update the cursor, please simply use the synchronous function to do HTTP requests and then return the cursor with the data you want.