Question

我创建了一个扩展RealmObject的类，每当我尝试运行该类时，我都会得到runTime异常，如下所示：

06-09 00：58：16.333 30719-30719 / com.khaalijeb.inkdrops E / AndroidRuntime：致命异常：主要过程：com.khaalijeb.inkdrops，PID：30719 io.realm.exceptions.RealmMigrationNeededException：由于以下错误，需要迁移： - Class＆＃39; transactionacknowledgedata＆＃39;已被添加。 at io.realm.internal.OsSharedRealm.nativeGetSharedRealm（Native Method）在io.realm.internal.OsSharedRealm。（OsSharedRealm.java:171） at io.realm.internal.OsSharedRealm.getInstance（OsSharedRealm.java:241）在io.realm.BaseRealm。（BaseRealm.java:136）在io.realm.BaseRealm。（BaseRealm.java:105）在io.realm.Realm。（Realm.java:164） at io.realm.Realm.createInstance（Realm.java:435）在io.realm.RealmCache.doCreateRealmOrGetFromCache（RealmCache.java:342）在io.realm.RealmCache.createRealmOrGetFromCache（RealmCache.java:282）在io.realm.Realm.getDefaultInstance（Realm.java:343）在com.khaalijeb.inkdrops.Fragment.NewPendingFragment.onCreate（NewPendingFragment.java:147）在android.support.v4.app.Fragment.performCreate（Fragment.java:2236）在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1285）在android.support.v4.app.FragmentTransition.addToFirstInLastOut（FragmentTransition.java:1085）在android.support.v4.app.FragmentTransition.calculateFragments（FragmentTransition.java:976）在android.support.v4.app.FragmentTransition.startTransitions（FragmentTransition.java:95）在android.support.v4.app.FragmentManagerImpl.executeOpsTogether（FragmentManager.java:2198）在android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps（FragmentManager.java:2155）在android.support.v4.app.FragmentManagerImpl.execSingleAction（FragmentManager.java:2034）在android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss（BackStackRecord.java:626）在android.support.v4.app.FragmentPagerAdapter.finishUpdate（FragmentPagerAdapter.java:143）在android.support.v4.view.ViewPager.populate（ViewPager.java:1268）在android.support.v4.view.ViewPager.populate（ViewPager.java:1116）在android.support.v4.view.ViewPager.onMeasure（ViewPager.java:1642）在android.view.View.measure（View.java:23167）在android.widget.RelativeLayout.measureChildHorizontal（RelativeLayout.java:715）在android.widget.RelativeLayout.onMeasure（RelativeLayout.java:461）在android.view.View.measure（View.java:23167）在android.widget.RelativeLayout.measureChildHorizontal（RelativeLayout.java:715）在android.widget.RelativeLayout.onMeasure（RelativeLayout.java:461）在android.view.View.measure（View.java:23167）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6749）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在android.view.View.measure（View.java:23167）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6749）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在android.support.v7.widget.ContentFrameLayout.onMeasure（ContentFrameLayout.java:139）在android.view.View.measure（View.java:23167）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6749）在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1535）在android.widget.LinearLayout.measureVertical（LinearLayout.java:825）在android.widget.LinearLayout.onMeasure（LinearLayout.java:704）在android.view.View.measure（View.java:23167）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6749）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在android.view.View.measure（View.java:23167）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6749）在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1535）在android.widget.LinearLayout.measureVertical（LinearLayout.java:825）在android.widget.LinearLayout.onMeasure（LinearLayout.java:704）在android.view.View.measure（View.java:23167）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6749）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在com.android.internal.policy.DecorView.onMeasure（DecorView.java:716） 06-09 00：58：16.334 30719-30719 / com.khaalijeb.inkdrops E / AndroidRuntime：在android.view.View.measure（View.java:23167）在android.view.ViewRootImpl.performMeasure（ViewRootImpl.java:2693）在android.view.ViewRootImpl.measureHierarchy（ViewRootImpl.java:1559）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1830）在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1447）在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:7130）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:935）在android.view.Choreographer.doCallbacks（Choreographer.java:747）在android.view.Choreographer.doFrame（Choreographer.java:682）在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:921）在android.os.Handler.handleCallback（Handler.java:873）在android.os.Handler.dispatchMessage（Handler.java:99）在android.os.Looper.loop（Looper.java:193）在android.app.ActivityThread.main（ActivityThread.java:6642） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:493）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:858）

我不知道为什么我会收到此错误。那里的任何人都面临这个问题吗？

Answer 1

请记住，在SQLite中你想添加一个表，所以你必须这样做：

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    int currentVersion = oldVersion;
    if(currentVersion == 1) {
        db.execSql("CREATE TABLE Blah(personId int, name varchar(255))");
        currentVersion++;
    }
    ...
}

等等？

Well Realm不是SQLite，但它仍然需要您修改架构以添加新的模型类并应用所需的架构更改。

因此，您需要定义一个迁移（see this whole section about it in the docs）来处理从X到Y的架构版本更改。

所以你创建了一个迁移：

public class Migration implements RealmMigration {

    @Override
    public void migrate(final DynamicRealm realm, long oldVersion, long newVersion) {
        ...
    }

    @Override
    public int hashCode() { return Migration.class.hashCode(); }

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

Bump架构版本并指定迁移到RealmConfiguration

Realm.setDefaultConfiguration(new RealmConfiguration.Builder()
                                    .schemaVersion(currentVersion+1) // probably a constant somewhere
                                    .migration(new Migration())
                                    .build());

您实际上需要使用添加新添加的类的DynamicRealm API编写迁移。

@Override
public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
    RealmSchema schema = realm.getSchema();
    if(oldVersion == 0) {
        RealmObjectSchema transactionacknowledgedata = 
                               schema.create("transactionacknowledgedata");
        transactionacknowledgedata.addField("name", String.class);
        oldVersion++;
    }
}

好吧，或者你设置new RealmConfiguration.Builder().deleteIfMigrationNeeded().build()，只要模型发生变化，你就会删除（并重新创建）Realm。

我在创建新的Realm类时遇到迁移错误？

1 个答案: