Google app engine 使用Objectify保存实体时出错
这是我尝试持久化实体时出现的错误：Google app engine 使用Objectify保存实体时出错,google-app-engine,objectify,Google App Engine,Objectify,这是我尝试持久化实体时出现的错误： com.googlecode.objectify.SaveException: Error saving com.mycomp.simplify.KeyValueVersion@60991f: You cannot create a Key for an object with a null @Id. Object was com.mycomp.simplify.Key@1bf3d87 at com.googlecode.objectify.impl.
com.googlecode.objectify.SaveException: Error saving com.mycomp.simplify.KeyValueVersion@60991f: You cannot create a Key for an object with a null @Id. Object was com.mycomp.simplify.Key@1bf3d87
at com.googlecode.objectify.impl.Transmog.save(Transmog.java:102)
at com.googlecode.objectify.impl.Concret
> Blockquote
eEntityMetadata.save(ConcreteEntityMetadata.java:150)
at com.googlecode.objectify.impl.engine.WriteEngine.save(WriteEngine.java:68)
at com.googlecode.objectify.impl.cmd.SaverImpl.entities(SaverImpl.java:56)
at com.googlecode.objectify.impl.cmd.SaverImpl.entity(SaverImpl.java:33)
at com.mycomp.simplify.core.ObjectifyGenericDao.put(ObjectifyGenericDao.java:52)
at com.mycomp.simplify.SimplifyImpl.access$0(SimplifyImpl.java:1)
at com.mycomp.simplify.SimplifyImpl$1.run(SimplifyImpl.java:43)
at com.mycomp.simplify.SimplifyImpl$1.run(SimplifyImpl.java:1)
at com.googlecode.objectify.impl.cmd.ObjectifyImpl.transactOnce(ObjectifyImpl.java:255)
at com.googlecode.objectify.impl.cmd.ObjectifyImpl.transactNew(ObjectifyImpl.java:232)
at com.googlecode.objectify.impl.cmd.ObjectifyImpl.transactNew(ObjectifyImpl.java:222)
at com.googlecode.objectify.impl.cmd.ObjectifyImpl.transact(ObjectifyImpl.java:214)
at com.googlecode.objectify.util.cmd.ObjectifyWrapper.transact(ObjectifyWrapper.java:165)
at com.mycomp.simplify.SimplifyImpl.put(SimplifyImpl.java:37)
at com.mycomp.simplify.ResourceTest.testCreateFetch(ResourceTest.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.IllegalArgumentException: You cannot create a Key for an object with a null @Id. Object was com.mycomp.simplify.Key@1bf3d87
at com.googlecode.objectify.impl.translate.EntityClassTranslator.getRawKey(EntityClassTranslator.java:160)
at com.googlecode.objectify.ObjectifyFactory.getRawKey(ObjectifyFactory.java:270)
at com.googlecode.objectify.impl.translate.EntityReferenceTranslatorFactory$1.saveValue(EntityReferenceTranslatorFactory.java:39)
at com.googlecode.objectify.impl.translate.EntityReferenceTranslatorFactory$1.saveValue(EntityReferenceTranslatorFactory.java:1)
at com.googlecode.objectify.impl.translate.ValueTranslator.savePropertyValue(ValueTranslator.java:51)
at com.googlecode.objectify.impl.translate.PropertyValueNodeTranslator.saveAbstract(PropertyValueNodeTranslator.java:38)
at com.googlecode.objectify.impl.translate.AbstractTranslator.save(AbstractTranslator.java:38)
at com.googlecode.objectify.impl.TranslatableProperty.executeSave(TranslatableProperty.java:145)
at com.googlecode.objectify.impl.translate.ClassTranslator.saveMap(ClassTranslator.java:94)
at com.googlecode.objectify.impl.translate.MapNodeTranslator.saveAbstract(MapNodeTranslator.java:38)
at com.googlecode.objectify.impl.translate.AbstractTranslator.save(AbstractTranslator.java:38)
at com.googlecode.objectify.impl.Transmog.saveToNode(Transmog.java:109)
at com.googlecode.objectify.impl.Transmog.save(Transmog.java:96)
... 39 more
对于要使用Objectify持久化的每个实体，都应该有一个类型为Long、Long或带有@Id注释的String的属性。这被用作实体的键。有关详细信息，请参阅
希望有帮助 对于要使用Objectify持久化的每个实体，都应该有一个类型为Long、Long或String且带有@Id注释的属性。这被用作实体的键。有关详细信息，请参阅
希望有帮助 您的实体类中有一个实体引用，它没有id。也就是说，类似这样：
@Entity
class MyEntity {
@Id Long id;
OtherEntity other; // this thing has a null id
}
@Entity
class MyEntity {
@Id Long id;
Ref<OtherEntity> other;
public OtherEntity getOther() { return other.get(); }
public void setOther(OtherEntity value) { this.other = Ref.create(value); }
}
@实体
类实体{
@Id长Id；
参考其他；
public OtherEntity getOther（）{return other.get（）；}
public void setOther（OtherEntity值）{this.other=Ref.create（value）；}
}
此模式消除了混淆，因为当您尝试创建无效引用时，会立即出现一个明确的异常。您的实体类中有一个没有id的实体引用。也就是说，类似这样的情况：
@Entity
class MyEntity {
@Id Long id;
OtherEntity other; // this thing has a null id
}
@Entity
class MyEntity {
@Id Long id;
Ref<OtherEntity> other;
public OtherEntity getOther() { return other.get(); }
public void setOther(OtherEntity value) { this.other = Ref.create(value); }
}
@实体
类实体{
@Id长Id；
参考其他；
public OtherEntity getOther（）{return other.get（）；}
public void setOther（OtherEntity值）{this.other=Ref.create（value）；}
}
这种模式消除了混淆，因为当您尝试创建无效引用时，会立即得到一个明确的异常。我刚刚遇到了这个异常并解决了它 如果无法使用now（）方法同步自动生成一个长Id，然后尝试使用该Id，则可以获得确切的stacktrace输出 坏的
ofy().save().entity(myEntity);
Ref.create(myEntity);
ofy().save().entity(myEntity).now();
Ref.create(myEntity);
ofy().save().entity(myEntity);
Ref.create(myEntity);
ofy().save().entity(myEntity).now();
Ref.create(myEntity);
您可能遇到该异常的原因有多种。忘记设置@Id注释不是其中之一。我刚刚遇到了这个异常，并解决了它 如果无法使用now（）方法同步自动生成一个长Id，然后尝试使用该Id，则可以获得确切的stacktrace输出 坏的
ofy().save().entity(myEntity);
Ref.create(myEntity);
ofy().save().entity(myEntity).now();
Ref.create(myEntity);
ofy().save().entity(myEntity);
Ref.create(myEntity);
ofy().save().entity(myEntity).now();
Ref.create(myEntity);
您可能遇到该异常的原因有多种。忘记设置@Id注释不是其中之一。我尝试了“Ref.create（value）”，但它给出了一个错误，这就是您的意思：“Ref.create（value.getKey（），value）”吗？如果这是执行Ref.create的正确方法，那么我如何执行getKey（）：是的，使用Ref.create（key，value）。Ref.create（value）方法尚未发布，但很快就会发布。我尝试了“Ref.create（value）”，但它给出了一个错误，您的意思是：“Ref.create（value.getKey（），value）”吗？如果这是执行Ref.create的正确方法，那么如何执行getKey（）：是的，使用Ref.create（key，value）。Ref.create（value）方法尚未发布，但很快就会发布。