Android：从MediaStore.Audio.Genres.Members表中删除条目

Question

I am writing an Android music player capable of editing MP3 song genres.

The procedure I'm following is:

1. Edit the genre tag in the MP3 file itself
2. Update the SqlLite MediaStore.Audio.Genres tables to reflect the changes (I do not want to trigger a lengthy 'rescan' operation for Android to pickup the changes itself)

My research suggests I need to modify MediaStore.Audio.Genres.Members table (ie this is the table I use to fetch the genre info).

My issue is a seemingly simple delete operation is not working as expected.

Note: I do know NOT to use hardcoded URIs as shown, but this is just test code...

String uriStr = "content://media/external/audio/genres/2/members";
Uri uri = Uri.parse(uriStr);

// Query the table for the row with ID=5448
Cursor cursor = context.getContentResolver().query(uri, null, BaseColumns._ID + "=5448", null, null);
Log.v("Test", "Row count: " + cursor.getCount());
cursor.close();

// Try to delete row 5448
int rowsCount = context.getContentResolver().delete(uri, BaseColumns._ID + "=5448", null);
Log.v("Test", "Rows deleted: " + rowsCount);

// Try (again) to delete row 5448
rowsCount = mService.getContentResolver().delete(uri, BaseColumns._ID + "=?", new String[]{"5448"});
Log.v("Test", "Rows deleted: " + rowsCount);

// Query (again) the table for the row with ID=5448         
Cursor cursor1 = mService.getContentResolver().query(uri, null, BaseColumns._ID + "=5448", null, null);
Log.v("Test", "Row count: " + cursor1.getCount());
cursor1.close();

The log of the above code is...

Row count: 1
Rows deleted: 0
Rows deleted: 0
Row count: 1

Why does the above query return a valid entry, but the deletes fail???

Answer 1

It does not make sense to edit the table. The android will automatically update this with what it finds on your tagged music. Why not look at the problem from an mp3 perspective? Present the user with a list of Genres, offer a replace function and then update the tracks with the new genre,

Answer 2

也许您不需要更多，但是如果您这样做，我可以为我提供解决方案的建议：在显示流派时，只需检查每种流派具有的曲目数，如果为0，就不要显示此流派。

Answer 3

You would rather use the AUDIO_ID column and not BaseColumns._ID because it is possible that row ids are updated each time you delete a row.

Here is what I do in my own app (tested and working fine on Android 4.0.4) :

context.getContentResolver().delete(MediaStore.Audio.Genres.Members.getContentUri(
                "external", genreId), MediaStore.Audio.Genres.Members.AUDIO_ID + " = " + song.getId(), null);