领域添加两个表而不会丢失任何数据

Question

我想添加两个表而不丢失旧表中的任何数据。所以我创建了表 “情感”

public class Emotion extends RealmObject {
    private String uuid;
    private String name;

和情感价值

public class EmotionValue extends RealmObject {

    private String uuid;
    private String emotionId;
    private String name;

我的RealmMigrations 有这个代码

public class RealmMigrations implements RealmMigration {

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

...

    if(oldVersion == 5) {
                schema.create("Emotion")
                        .addField("uuid", String.class)
                        .addField("name", String.class);

                schema.create("EmotionValue")
                        .addField("uuid", String.class)
                        .addField("emotionId", String.class)
                        .addField("name", String.class);

                oldVersion++;
            }

我的App 有

public class App extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        Realm.init(getApplicationContext());
        RealmConfiguration config = getRealmConfig("superdatabase");
        Realm.setDefaultConfiguration(config);

        Stetho.initialize(
                Stetho.newInitializerBuilder(this)
                        .enableDumpapp(Stetho.defaultDumperPluginsProvider(this))
                        .enableWebKitInspector(RealmInspectorModulesProvider.builder(this).build())
                        .build());
    }

    public static RealmConfiguration getRealmConfig(String name) {
        return new RealmConfiguration.Builder()
                .name(name)
                .schemaVersion(5)
                .migration(new RealmMigrations())
                .build();
    }
}

当我运行应用程序时出现错误：

  Caused by: io.realm.exceptions.RealmMigrationNeededException: Migration is required due to the following errors:
    - Class 'Emotion' has been added.
    - Class 'EmotionValue' has been added.
        at io.realm.internal.OsSharedRealm.nativeGetSharedRealm(Native Method)
        at io.realm.internal.OsSharedRealm.<init>(OsSharedRealm.java:171)
        at io.realm.internal.OsSharedRealm.getInstance(OsSharedRealm.java:241)
        at io.realm.BaseRealm.<init>(BaseRealm.java:135)
        at io.realm.BaseRealm.<init>(BaseRealm.java:103)
        at io.realm.Realm.<init>(Realm.java:163)
        at io.realm.Realm.createInstance(Realm.java:499)
        at io.realm.RealmCache.doCreateRealmOrGetFromCache(RealmCache.java:341)
        at io.realm.RealmCache.createRealmOrGetFromCache(RealmCache.java:284)
        at io.realm.Realm.getInstance(Realm.java:428)
        at com.timecontrolapp.models.App.onCreate(App.java:17)
        at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1012)
        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4553)

在 com.timecontrolapp.models.App.onCreate(App.java:17) 有这一行 Realm.setDefaultConfiguration(config);。我的问题是，如何在不丢失旧数据库中的任何数据的情况下将一些表添加到现有数据库中？

Answer 1

所以你只需要升级 schemaVersion() ，在你的情况下是 6 而不是 5。