When using a write Screenlet that supports offline mode, new data written to the cache must also be synced with the server. The write Screenlets included with Liferay Screens do this for you. However, you must do this manually when using a custom write Screenlet. You should do this in the activity or fragment that uses the Screenlet–exactly where in this activity or fragment is up to you though.
To sync a write Screenlet’s data with the server manually, follow these steps:
- Retrieve the event that needs to be synced with the server. To do this, you
must first get the cache key associated with the event. Then use the key as
an argument to the
Cache.getObjectmethod. - Call the Interactor with the event. This syncs the data with the server.
For example, the following code uses the Cache.findKeys method to retrieve all
BookmarkEvent keys in the cache. The loop that follows then retrieves the
event that corresponds to each key, and syncs it to the server by calling the
Interactor:
String[] keys = Cache.findKeys(BookmarkEvent.class, groupId, userId, locale, 0,
Integer.MAX_VALUE);
for (String key : keys) {
BookmarkEvent event = Cache.getObject(BookmarkEvent.class, groupId, userId, key);
new AddBookmarkInteractor().execute(event);
}
Note that if you opted not to set a cache key in your Screenlet class, you can
pass null in place of a key.
Also note that you can use Android’s SharedPreferences APIs as an alternative
way to store and retrieve cache keys. For example, the following code stores
cache keys in shared preferences:
SharedPreferences sharedPreferences = getSharedPreferences("MY_PREFERENCES", Context.MODE_PRIVATE);
HashSet<String> values = new HashSet<>();
sharedPreferences.edit().putStringSet("keysToSync", values).apply();
You can then retrieve the keys as you would retrieve any other key-value set from shared preferences:
SharedPreferences sharedPreferences = getSharedPreferences("MY_PREFERENCES", Context.MODE_PRIVATE);
HashSet<String> keysToSync = sharedPreferences.getStringSet("keysToSync", new HashSet<>());