Realm Exception 'value' is not a valid managed object

Question

I'm setting a property on a realm object with another realm object which is a different class, however I'm getting the error: 'value' is not avalid managed object.

realmObject.setAnotherRealmObject(classInstance.returnAnotherRealmObjectWithValues())

The class instance receives anotherRealmObject constructor and returns it through the method with values from widgets:

public ClassInstance(AnotherRealmObject anotherRealmObject){
  mAnotherRealmObject = anotherRealmObject;
}

public AnotherRealmObject returnAnotherRealmObjectWithValues(){
       mAnotherRealmObject.setId(RandomUtil.randomNumbersAndLetters(5));
       mAnotherRealmObject.setName(etName.getText().toString());

       return mAnotherRealmObject;
}

I'm creating the new Another Realm Object the right way (I think):

mAnotherRealmObject = mRealmInstance.createObject(AnotherRealmObject.class);

Is it because I'm returning anotherRealmObject wherein it is already modified because of the passing reference?

Answer 1

Upon researching there is a method on realm objects to check if it is valid:

realmObject.isValid();

There are two ways I know how to instantiate a realmObject:

RealmObject realmObj = new RealObject(); //Invalid
RealmObject realmObj = realmInstance().createObject(RealmClass.class); //Valid

I was using parceler to pass realmObjects around. Passing a realmObject through parceler and unwrapping it and assigning it to a realmObject variable would make it invalid:

RealmObject realmObj = Parcels.unwrap(data.getParcelableExtra("realmObject"));

Solution 1 - Pass the unique identifer, then query the realm object:

int uniqueId = Parcels.unwrap(data.getParcelableExtra("uniqueId"));

Solution 2 - Pass the values, retrieve it, create a realmObject through a realmInstance and assign the values.

//Retrieve values
String value1 = Parcels.unwrap(data.getParcelableExtra("value1"));
String value2 = Parcels.unwrap(data.getParcelableExtra("value2"));

//Create realmObject 'properly'
RealmObject realmObj = realmInstance().createObject(RealmClass.class);

//Assign retrieved values
realmObj.setValue1(value1);
realmObj.setValue2(value2);

This way you won't get an invalid realm object.

Answer 2

All managed RealmObjects and RealmResults belong to a specific Realm instance. After the corresponding Realm instance gets closed, the RealmObject becomes invalid.

Like below case:

Realm realm = Realm.getInstance(context);
realm.beginTransaction();
MyObject obj = realm.createObject(MyObject.class);
realm.commitTransaction();
realm.close();

realm = Realm.getInstance(context);
realm.beginTransaction();
MyObject obj2 = realm.where(MyObject2.class).findFirst();
obj2.setObj1(obj); // Throws exception, because of the obj's Realm instance is closed. It is invalid now.
realm.commitTransaction();

You may get some ideas about control the Realm's instance life cycle through this doc