Why CalendarProvider doesn't allow writing ExtendedProperties?

Question

Google calendar events have extended properties that can be used to attach name/value pairs to an event.

We are implementing a collaborative calendar application that uses those extended properties to attach extra information to the event. As recommended by Google, we use the Android CalendarProvider to read and create new events. When we create a new event we need to add some extended properties to it but we just realised that the calendar provider doesn't allow writing CalendarContract.ExtendedProperties, if we try we get the following error:

Only sync adapters may write using content://com.android.calendar/extendedproperties

It seems a bit weird that these properties are read-only in the CalendarProvider because it defeats the whole purpose of them that is being able to attach some extra metadata to the event.

Does anyone know a workaround for this limitation?

Answer 1

you have to proceed as below :

• the class you use for saving events with extended propeties should extends AbstractThreadedSyncAdapter , then implements the method onPerfomSync(...)

  public void onPerformSync(Account account, Bundle extras, String authority,
      ContentProviderClient provider, SyncResult syncResult) {
  System.out.println("Sync......");
  saveEvent();//your saving events method... 
  

  }

add the method below in the same class :

    static Uri asSyncAdapter(Uri uri, String account, String accountType) {
    return uri.buildUpon()
        .appendQueryParameter(android.provider.CalendarContract.CALLER_IS_SYNCADAPTER,"true")
        .appendQueryParameter(Calendars.ACCOUNT_NAME, account)
        .appendQueryParameter(Calendars.ACCOUNT_TYPE, accountType).build();
 }

create a class that extends the Service class like below

public class SyncService extends Service {
private static final String TAG = "SyncService";

private static final Object sSyncAdapterLock = new Object();
private static EditEventHelper sSyncAdapter = null;

/**
 * Thread-safe constructor, creates static {@link SyncAdapter} instance.
 */
@Override
public void onCreate() {
    super.onCreate();
    Log.i(TAG, "Service created");
    synchronized (sSyncAdapterLock) {
        if (sSyncAdapter == null) {
            sSyncAdapter = new EditEventHelper(getApplicationContext());

        }
    }
}

@Override
/**
 * Logging-only destructor.
 */
public void onDestroy() {
    super.onDestroy();
    Log.i(TAG, "Service destroyed");
}

/**
 * Return Binder handle for IPC communication with {@link SyncAdapter}.
 *
 * <p>New sync requests will be sent directly to the SyncAdapter using this channel.
 *
 * @param intent Calling intent
 * @return Binder handle for {@link SyncAdapter}
 */
@Override
public IBinder onBind(Intent intent) {
    return sSyncAdapter.getSyncAdapterBinder();
}

}

In the res path create an xml file syncadpater.xml with the content :

<sync-adapter xmlns:android="http://schemas.android.com/apk/res/android"
          android:contentAuthority="com.android.calendar"
          android:accountType="com.android.google"
          android:userVisible="true"
          android:supportsUploading="false"
          android:allowParallelSyncs="false"
          android:isAlwaysSyncable="false"
    />

The code for used for adding an Extendedproperties to you event, will be :

ContentValues customerContentValues_1 = new ContentValues(); 
        customerContentValues_1.put(ExtendedProperties.EVENT_ID, model.mId);
        customerContentValues_1.put(ExtendedProperties.NAME, "name");
        customerContentValues_1.put(ExtendedProperties.VALUE, value);
activity.getContentResolver().insert(asSyncAdapter(ExtendedProperties.CONTENT_URI, mOwnerAccount, ACCOUNT_TYPE), customerContentValues_1);

In the AndroidManifest.xml file add these permissions :

    <uses-permission android:name="android.permission.READ_SYNC_STATS" />
<!-- Required to enable our SyncAdapter after it's created. -->
<uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS" />
<!-- Required because we're manually creating a new account. -->
<uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS" />

Then declare the Service that you've create into the manifest file associated to the syncadapter.xml file:

        <service
        android:name="com.android.calendar.iselection.event.SyncService"
        android:exported="true" >

        <!--
        This intent filter is required. It allows the system to launch our sync service
        as needed.
        -->
        <intent-filter>
            <action android:name="android.content.SyncAdapter" />
        </intent-filter>
        <!-- This points to a required XML file which describes our SyncAdapter. -->
        <meta-data
            android:name="android.content.SyncAdapter"
            android:resource="@xml/syncadapter" />
    </service>

Good luck!