CODEWITHSUNDEEP
androidrealm
RJH
RJH

Reputation: 358

Realm Migration Issues

I have an issue with getting Realm to migrate successfully and could do with a little help having been tinkering with it for a couple of weeks now..

I have a realm db working by which I mean saving data and and returning data.

Lets say I want to add a new field "username". I update my RealmObject code to utilise the new field. In my App.java I then use:

   System.out.println("Configuring Realm...");
   RealmConfiguration config1 = new RealmConfiguration.Builder(this)
            .schemaVersion(1)
            .migration(new Migration())
            .build();
   realm = Realm.getInstance(config1);
   realm.close();

My Migration.java looks like:

public class Migration implements RealmMigration {
    @Override
    public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
        RealmSchema schema = realm.getSchema();
        RealmObjectSchema theSchema = schema.get("RealmStore");
        System.out.println("Realm version is " + oldVersion);
        if (oldVersion == 0) {
            theSchema
                    .addField("username", String.class);
            oldVersion++;
            System.out.println("Realm migrated from 0 to 1");
        }
    }
}

I run the app and the following output is given:

I/System.out: Configuring Realm...
I/System.out: Realm version is 0
I/System.out: Realm migrated from 0 to 1

All good! Except..! When you re-run the app, you now get the following error:

E/AndroidRuntime: FATAL EXCEPTION: main
E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rh.realmy/com.rh.realmy.Main}: java.lang.IllegalArgumentException: Realm on disk is newer than the one specified: v1 vs. v0

Any ideas?

Upvotes: 2

Views: 1449

Answers (2)

RJH
RJH

Reputation: 358

Kohi:

This is the code I used in the end (which works)...

In my App.java:

private Realm realm;
@Override
public void onCreate() {
    super.onCreate();

    // Setup Realm
    RealmConfiguration config1 = new RealmConfiguration.Builder(this)
            .schemaVersion(0)
            .migration(new Migration())
            .build();
    realm = Realm.getInstance(config1); // Automatically run migration if needed
    Realm.setDefaultConfiguration(config1);
    realm.close();
    }
}

In my class that uses realm:

private Realm realm;
@Override
protected void onCreate(Bundle savedInstanceState) {
// Open the default Realm for the UI thread.
    realm = Realm.getDefaultInstance();
}

Then use realm as needed

Hope this helps

Upvotes: 2

Christian Melchior
Christian Melchior

Reputation: 20126

The problem is that in other parts of the code you are calling Realm.getInstance(context).

This is equivalent to doing the following:

RealmConfiguration config = new RealmConfiguration.Builder(context).schemaVersion(0).build();
Realm realm = Realm.getInstance(config);

Which will give you the schema mismatch error you are seeing.

You can read more about default configurations here: https://realm.io/docs/java/latest/#the-default-realm

Upvotes: 3

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