Styjun

In the app there is a realm database that has both initial data and data added by the user. The data added by the user should stay on the device even after the updates. The initial data is added through the class

public class RealmInitialData implements Realm.Transaction 

 @Override
 public void execute(Realm realm)
 //initial data
 Items item = new Items();
 item.setName("Fragrance");
 item.setTimestamp(System.currentTimeMillis());
 realm.insertOrUpdate(item);
 
 @Override
 public int hashCode() 
 return RealmInitialData.class.hashCode();
 

 @Override
 public boolean equals(Object obj) 
 return obj != null && obj instanceof RealmInitialData;
 

The configuration (situated in a class which extends Application class) looks like this:

RealmConfiguration realmConfig = new RealmConfiguration.Builder()
 .name("tasky.realm")
 .schemaVersion(2)
 .migration(new Migration())
 .initialData(new RealmInitialData())
 .build();

If I change/add something in the RealmInitialData for update, the data on the user application doesn't change. How can I both change the initial data (add or rewrite sth) and make no changes to the user's data?

You have to implement RealmMigration and pass it to RealmConfiguration.Builder().migration().
Something like this:

public class RealmMigrationAgent implements RealmMigration

 @Override
 public void migrate(DynamicRealm realm, long oldVersion, long newVersion) 
 RealmSchema schema = realm.getSchema();

 if (oldVersion == 0) 
 schema.get("InventDisableObject").addField("Reason", int.class);
 oldVersion++;
 

 if (oldVersion == 1) 
 if (!schema.get("ActionObject").hasField("Annual"))
 schema.get("ActionObject").addField("Annual", boolean.class);
 oldVersion++;
 
 if (oldVersion == 2) 
 if (!schema.get("ActionObject").hasField("Hash"))
 schema.get("ActionObject").addField("Hash", String.class);
 if (!schema.get("ActionObject").hasField("Manual"))
 schema.get("ActionObject").addField("Manual", boolean.class);
 oldVersion++;
 
 if (oldVersion == 3) 
 if (!schema.get("OutletObject").hasField("Code"))
 schema.get("OutletObject").addField("Code", String.class);
 oldVersion++;
 
 

Incrementally adding scheme updates for every new scheme version.
I can see you have some class Migration for migration reason - can you provide the code of it?

I have the same problem and i find the way.For example,if your new version is 7,try to use SharedRealm.getInstance(config).getSchemaVersion() to get the old version 6 before Realm.setDefaultConfiguration(config),then you can update old realm data after setDefaultConfiguration which old version < 7.May this can help you:

RealmConfiguration config = new RealmConfiguration.Builder()
 .schemaVersion(7)
 .migration(new RealmMigration() 
 @Override
 public void migrate(DynamicRealm realm, long oldVersion, long newVersion) 
 RealmSchema schema = realm.getSchema();
 if(oldVersion == 6) 
 schema.get("ImageRealm")
 .addField("isSelected", Boolean.class, FieldAttribute.REQUIRED)
 .addField("isLow", Boolean.class, FieldAttribute.REQUIRED);
 oldVersion++;
 
 
 ).build();

 SharedRealm sharedRealm = SharedRealm.getInstance(config);
 long oldVersion = sharedRealm.getSchemaVersion();

 Realm.setDefaultConfiguration(config);
 long newVersion = Realm.getDefaultInstance().getVersion();

 // 如果有历史记录，更新状态
 if (oldVersion < 7) 
 Realm.getDefaultInstance().executeTransaction(new Realm.Transaction() 
 @Override
 public void execute(Realm realm) 
 RealmResults<DocRealmBean> allData = realm.where(DocRealmBean.class).findAll();
 for (DocRealmBean bean : allData) 
 bean.state = "0";
 
 
 );