juanes666 juanes666 -4 years ago 158
Android Question

RealmObject changeListener

I'm trying to understand notification types in Realm from the Notifications section in the official docs, and when I'm using RealmObject addChangeListener in multiple managed object all of them are called when only one object is changing.

This is my code

Person first = realm.where(Person.class).equalTo("id", 0).findFirst();

first.addChangeListener(new RealmChangeListener<Person>() {
@Override
public void onChange(Person person) {
Log.e(LOG_TAG, "First element is changing: " + person);
}
});

Person second = realm.where(Person.class).equalTo("id", 1).findFirst();

second.addChangeListener(new RealmChangeListener<Person>() {
@Override
public void onChange(Person person) {
Log.e(LOG_TAG, "Second person is changing: " + person);
}
});


When I trigger an update in any of these Person objects (for example in first) both of the listeners are being called.

This what official docs say:


Listeners can also be attached to RealmObject instances as well as RealmResults instances. This allows you to react to changes to your objects and query results.


And


Lastly, typed-based change listeners will get notified when their referenced types change.


From what I understand the seen behaviour agrees with the second definition but I need to use the first behaviour, that's, I want to be notified when the object corresponding to that listener is changed.
So, if first Person is updated, only its corresponding listener get notified, not all Person listeners.

Answer Source

Right now it is happening because our change detection is not granular enough. It will trigger change listeners for all objects of the same type, not just those that changed.

Getting the changelisteners to only notify if the exact object has changed is being tracked here https://github.com/realm/realm-java/issues/989.

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