[ContentObservable] Added loadCursor and registerContentObserver

[henrytao-me]

Hi all, I think it's quite interesting and useful to have these two methods when you want to handle cursor outside loaderManager lifecycle. I will write more test cases then.

Current code

public void loadCursorInBackground(Context context, Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder, final AsyncCallback<Cursor> callback) {
    start(callback);
    execute(new Runnable() {
      @Override
      public void run() {
        try {
          Cursor cursor = mContext.getContentResolver().query(uri, projection, selection, selectionArgs, sortOrder);
          success(callback, cursor);
        } catch (Exception e) {
          failure(callback, e);
        }
      }
    });
}

Rx code

ContentObservable.loadCursor(getActivity(), uri, projection, selection, selectionArgs, sortOrder)
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(cursor -> onCursorLoaded(cursor))

Current code

ContentResolver contentResolver = activity.getContentResolver();
contentResolver.registerContentObserver(ChatMessageProvider.CONTENT_URI, false, mChatRoomContentObserver);

Rx code

ContentObservable.registerContentObserver(getActivity(), ChatMessageProvider.CONTENT_URI, false)
          .subscribeOn(Schedulers.io())
          .subscribe(selfChange -> loadChatRoomInBackground())

[lykhonis]

This ties to ContentResolver specifically, but we can have SQLiteDatabase and other potential Cursor providers. What about this way: #180 ?

[JakeWharton]

As part of #172 this functionality has been removed from future releases. SqlBrite is about to have a 0.2 (probably today) and has functionality like this.

[Rainer-Lang]

@JakeWharton Should we all use SqlBrite? Is this the way to get functionality for ContentObservable back? What do you suggest?

[mttkay]

We’re also in the process of open sourcing a storage API that has natural
mappings to Rx (and comes with an Rx wrapper). It doesn’t use
ContentProvider though if that’s what you’re looking for.

On Fri, Aug 28, 2015 at 4:46 PM, Rainer-Lang notifications@github.com
wrote:

@JakeWharton https://github.com/JakeWharton Should we all use SqlBrite?
Is this the way to get functionality for ContentObservable back? What do
you suggest?

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[erickok]

There are many solutions already available, with more or less features and more or less Rx foxus, such as SqlBrite, RxCupboard, StorIO. Also looking forward to see mtkay's solution. But typically NOT as part of RxAndroid.

[Rainer-Lang]

@mttkay Could you give me some informations?
@erickok Thanks. I know the 3 libs - and maybe I'm using StorIO. But it's lot of work to migrate from an orm-lib....

[artem-zinnatullin]

BTW, if somebody has questions about StorIO — feel free to ask me (or file a question on SO) .

Main difference from SQLBrite and RxCupboard — all operations (Put, Get, Delete) can be executed as Observable, so you don't need to do manual multithreading. + Builders, Immutability and so on.

[Rainer-Lang]

I decided to use StorIO.