我有一个使用以前版本的领域的实时应用程序（v0.85.1），我正在使用版本4.2.0领域的新版本，并且还有架构更改。架构更改只是添加到一个表的单个列。对于迁移，我有这个课程。
public class ImRealmMigration implements RealmMigration{
@Override
public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
RealmSchema schema = realm.getSchema();
if(oldVersion == 0){
schema.get("Layout")
.addField("orientation", String.class, FieldAttribute.REQUIRED);
oldVersion++;
}
}
}
在应用程序类中我有这个
Realm.init(this);
RealmConfiguration realmConfiguration = new RealmConfiguration.Builder()
.name("default.realm")
.schemaVersion(1)
.migration(new ImRealmMigration())
.build();
Realm.setDefaultConfiguration(realmConfiguration); // Make this Realm the default
Realm realm = Realm.getInstance(realmConfiguration);
当我去运行应用程序时，它会一直运行，直到抛出RealmMigrationNeededException的最后一行，并继续列出架构中的所有主键，说它们已被设为可选。有谁知道为什么会这样，我能做些什么来解决它？这是堆栈跟踪：
FATAL EXCEPTION: main
java.lang.RuntimeException:
Unable to start activity io.realm.exceptions.RealmMigrationNeededException:
Migration is required due to the following errors:
- Property 'Book.privateId' has been made optional.
- Property 'BookType.bookTypeId' has been made optional.
- Property 'Cart.id' has been made optional.
- Property 'ClipArt.url' has been made optional.
- Property 'Contact.userId' has been made optional.
- Property 'CreditAccount.id' has been made optional.
- Property 'Layout.layoutId' has been made optional.
- Property 'LayoutClipArtItem.layoutItemId' has been made optional.
- Property 'LayoutItem.itemId' has been made optional.
- Property 'LayoutPhotoItem.layoutItemId' has been made optional.
- Property 'LayoutShapeItem.layoutItemId' has been made optional.
- Property 'LayoutTextItem.layoutItemId' has been made optional.
- Property 'OrderSession.id' has been made optional.
- Property 'PagePhoto.pagePhotoId' has been made optional.
- Property 'Photo.privateId' has been made optional.
- Property 'PhotoOrigin.identifier' has been made optional.
- Property 'PrintPack.privateId' has been made optional.
- Property 'PrintType.printTypeId' has been made optional.
- Property 'Product.productId' has been made optional.
- Property 'ProductFamilyMarketing.productFamilyType' has been made optional.
- Property 'Region.rid' has been made optional.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3151)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3261)
at android.app.ActivityThread.access$1000(ActivityThread.java:219)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1735)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6939)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
Caused by: io.realm.exceptions.RealmMigrationNeededException: Migration is required due to the following errors:
- Property 'Book.privateId' has been made optional.
- Property 'BookType.bookTypeId' has been made optional.
- Property 'Cart.id' has been made optional.
- Property 'ClipArt.url' has been made optional.
- Property 'Contact.userId' has been made optional.
- Property 'CreditAccount.id' has been made optional.
- Property 'Layout.layoutId' has been made optional.
- Property 'LayoutClipArtItem.layoutItemId' has been made optional.
- Property 'LayoutItem.itemId' has been made optional.
- Property 'LayoutPhotoItem.layoutItemId' has been made optional.
- Property 'LayoutShapeItem.layoutItemId' has been made optional.
- Property 'LayoutTextItem.layoutItemId' has been made optional.
- Property 'OrderSession.id' has been made optional.
- Property 'PagePhoto.pagePhotoId' has been made optional.
- Property 'Photo.privateId' has been made optional.
- Property 'PhotoOrigin.identifier' has been made optional.
- Property 'PrintPack.privateId' has been made optional.
- Property 'PrintType.printTypeId' has been made optional.
- Property 'Product.productId' has been made optional.
- Property 'ProductFamilyMarketing.productFamilyType' has been made optional.
- Property 'Region.rid' has been made optional.
at io.realm.internal.OsSharedRealm.nativeGetSharedRealm(Native Method)
at io.realm.internal.OsSharedRealm.<init>(OsSharedRealm.java:172)
at io.realm.internal.OsSharedRealm.getInstance(OsSharedRealm.java:219)
at io.realm.BaseRealm.<init>(BaseRealm.java:124)
at io.realm.BaseRealm.<init>(BaseRealm.java:93)
at io.realm.Realm.<init>(Realm.java:153)
at io.realm.Realm.createInstance(Realm.java:424)
at io.realm.RealmCache.doCreateRealmOrGetFromCache(RealmCache.java:342)
at io
答案 0 :(得分：3)
0.89.0
突破变化
对于String，Byte，Short，@PrimaryKey字段值现在可以为null 整数和长类型。应该使用迁移旧领域 RealmObjectSchema.setNullable（），或添加@Required注释 （＃2515）。
请参阅版本0.89.0的更改日志
您可以在@Required字段上添加@PrimaryKey，轻松绕过此问题。