How to convert RealmResults object to RealmList?

27
votes

I have a RealmResults <Student> object. I want to convert it to RealmList <Student> object. any suggestions?

10
androidrealm

10 Answers

22
votes
RealmList <Student> results = new RealmList<Student>();

results.addAll(realmResultList.subList(0, realmResultList.size()));
13
votes

Please try and let me know if this work for you.

RealmList <Student> finalList = new RealmList<Student>();

finalList.addAll(yourRealmResults.subList(0, yourRealmResults.size()));
13
votes

Since 0.87.0

  • Added Realm.copyFromRealm() for creating detached copies of Realm objects (#931).

Which allow just return list List<E extends RealmObject>

9
votes

RealmResults implements the List interface and so does the RealmList. 

RealmList <Student> results = new RealmList<Student>();
results.addAll(realmResultsList);
3
votes

In new update you can use copyFromRealm method to do so :

RealmList<Student> finalList = realm.copyFromRealm(resultsAnswers);
3
votes

RealmResults is returned if a query is expected to give a collection of objects (e.g. RealmQuery<E>.findAll()). Otherwise, single object queries will return a RealmObject.

Managed and Unmanaged Objects
RealmResults are managed objects, meaning they cannot be manipulated outside of Realm transactions and are confined in the thread that created them. Converting RealmResults into a RealmList will make the data unmanaged, as what @epicpandaforce pointed out, meaning the objects in the list are not connected to the database anymore and are basically normal Java objects which can be transferred in between threads and manipulated.

To convert RealmResults to a RealmList:

RealmResults<User> results = realm.where(User.class).findAll();
RealmList<Users> users = realm.copyFromRealm(results);

Changes to an unmanaged object will not in any means affect the original in the database unless a realm.copyToRealm(users), doing the opposite of copyFromRealm(), is executed after. Keep in mind that RealmLists can be managed or unmanaged, as a RealmObject from a RealmResult can have the following structure in which the RealmList in this case is a managed object: 

class User {
  int               id;
  String            name;
  RealmList<String> petNames;
}

Finally, copyFromRealm() returns a List so it's also possible to do 

ArrayList<User> users = realm.copyFromRealm(results);
2
votes

Realm has some new features check-in documentation Realm Documentation

Realm has copyfromRealm function which we can use to convert the result to list

RealmList<Student> student=realm.copyfromRealm(Realmresult);
0
votes

@JemshitIskenderov This should copy for you.

public RealmList<Student> convertResultToList(RealmResult<Student> realResultsList){
    RealmList <Student> results = new RealmList<Student>();

    for(Student student : realResultsList){
       results.add(copy(student));
    }
}

private Student copy(Student student){
    Student o = new Student();

    o.setCreated(student.getCreated());
    o.setModified(student.getModified());
    o.setDeleted(student.getDeleted());
    o.setName(student.getName());
    //List more properties here
    return o;
}
0
votes

Code:

public class RealmCollectionHelper {

     public static <C extends RealmModel> RealmList<C> mapperCollectionToRealmList(Collection<C> objects){
         if (objects == null){
             return null;
         }
         RealmList<C> realmList = new RealmList<>();
         realmList.addAll(objects);

         return realmList;
     }
}

Here my gist: https://gist.github.com/jmperezra/9b4708051eaa2686c83ebf76066071ff

0
votes

Just another way of doing it:

RealmList<YourClass> dummy = new RealmList<>();
Iterator<YourClass> it = realmResultsList.listIterator();
while (it.hasNext()) {
      dummy.add(it.next());
}