CODEWITHSUNDEEP
androidsqliteandroid-contentproviderandroid-loadermanager
dorjeduck
dorjeduck

Reputation: 7804

android - CursorLoader & SQLite without Content Provider

I know this has been discussed yet I wanted to ask about the current state of the matter. Do i have to create a ContentProvider to use CursorLoader in connection with a sqlite database?

I found

CursorLoader usage without ContentProvider

Looks exactly what I was hoping for yet as Emmby commented

So another solution is mentioned

https://github.com/commonsguy/cwac-loaderex

yet again some drawback is pointed out

Of course when using LoaderManager we want to get all the benefits for which it was introduced. So my question is if there is a way to use LoaderManager in connection with a sqlite database without having to implement a content provider yet have all the benefits of it.

Thanks

Upvotes: 54

Views: 21625

Answers (3)

rahim virani
rahim virani

Reputation: 23

how about having a boolean in shared preferences as false .. updating the content when that boolean is true.... and when any of the operations which changes the underlying database .. that boolean will be set to true and as shared preferences you a changelistener you can recieve changes live directly after the relevant methods are called

Upvotes: 0

Dev Ngo
Dev Ngo

Reputation: 21

Here is my solution, in my onCreateLoader

{
Uri u = Uri.parse("content://what_string_you_want");
return new CursorLoader(this, yourURI, projection, null, null, null) {
    private final ForceLoadContentObserver mObserver = new ForceLoadContentObserver();

    @Override
    public Cursor loadInBackground() {
        Cursor c = YOUR_DATABASE.doYourQuery(...);
        if (c != null) {
          // Ensure the cursor window is filled
           c.getCount();
           c.registerContentObserver(mObserver);
        }

        c.setNotificationUri(getContext().getContentResolver(), getUri());
        return c;
    }
};
}

After the code that will change DB, add

 getContentResolver().notifyChange(
            Uri.parse("content://same_with_first_string"), null);

Upvotes: 2

Alex Lockwood
Alex Lockwood

Reputation: 83311

The two implementations you mention in your post both offer all of the benefits of the CursorLoader except the ability to receive notifications when the underlying content changes.

I've been looking into this a lot recently and I can confidently tell you that the Android API currently does not provide a means of doing this with only a raw SQLiteDatabase (it only provides the ContentResolver#notifyChange() and Cursor#setNotificationUri() methods, which are used to notify all Cursors registered under a certain notification Uri).

That said, your options right now are to:

  1. Implement an observer yourself that is capable of receiving notifications from the SQLiteDatabase when the content changes, and is somehow able to relay these notifications to all existing Loaders in your application. I wrote a pretty extensive blog post on how to implement Loaders that might come in handy if you wish to take on this challenge. Or...

  2. Use Mark Murphy's LoaderEx library and only make database modifications using the AsyncTask operations his library provides. Note that the reason why his tasks refresh the Loader is because they call onContentChanged on the Loader immediately after the insertion/update/delete is performed, effectively telling the Loader that the content has changed and that it should refresh its data.

  3. Just use a ContentProvider with a CursorLoader and you can use the ContentResolver#notifyChange() method to notify the CursorLoader that a content change has occurred.

I'm trying to figure out a better solution, and I'll report back in the future if I ever find/implement one, but for now these will have to do.

Upvotes: 66

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