How to use CALLER_IS_SYNCADAPTER properly

Question

somehow I don\'t understand the working concept of the query parameter CALLER_IS_SYNCADAPTER. Its default value is false, if set, the DIRTY flag is not automatically set. So

Answer 1

Here is from Javadoc:

/** * An optional insert, update or delete URI parameter that allows the caller * to specify that it is a sync adapter. The default value is false. If true * the dirty flag is not automatically set and the "syncToNetwork" parameter * is set to false when calling * {@link ContentResolver#notifyChange(android.net.Uri, android.database.ContentObserver, boolean)}. */

.

The invocation of resolver.delete(...), does not immediately delete a raw contacts row. Instead, it sets the DELETED flag on the raw contact and removes the raw contact from its aggregate contact. The sync adapter then deletes the raw contact from the server and finalizes phone-side deletion by calling resolver.delete(...) again and passing the CALLER_IS_SYNCADAPTER query parameter.

Answer 2

CALLER_IS_SYNCADAPTER doesn't necessarily affect what's stored in the database row, it depends on the command performed. It shouldn't have an effect on queries. Do not use it from a user application on the device.

Now... Why does it exist?

It is provided to help with notifyChange() / ContentObservers / ContentResolver / Syncadapter integration. There are two use cases for changing a row in the database.

1. Local user edits from an application.
2. Changes come from the network (via SyncAdapter)

Either change requires the UI to update, if it's onscreen. Therefore ContentResolver.notifyChange(Uri uri, ContentObserver observer, boolean syncToNetwork) gets called. This updates ContentObservers and tells them to go fetch the newest data from the ContentProvider DB. That last parameter in the call is your clue.

ContentResolver itself is a ContentObserver. When it sees the database change, it considers starting up your SyncAdapter to push the change up to the network. This is great in case 1. In case 2, it's redundant. The change came from the network, there's no reason at all to start up a sync to send the change back.

Calendar.CALLER_IS_SYNCADAPTER is a cue used within the update() performed by the SyncAdapter. When it's true, ContentProvider sets syncToNetwork as false, ensuring a redundant second sync is not performed

A second example is as veljko mentioned. The cleanest way to delete a thing from the server is to set the delete flag, and then perform a sync. When the CALLER_IS_SYNCADAPTER flag is false (user app) a call to delete() sets the flag. When the flag is true (sync is happening), a call to delete() pushes the deletion up to the server and removes the row from the local DB. There's only one delete() call, this flag allows the ContentProvider to know which task it's supposed to do.

Answer 3

You can add to your existing Uri:

myUri=calendarUri.buildUpon().appendQueryParameter(Calendar.CALLER_IS_SYNCADAPTER, "true").build();