我似乎无法弄清楚是什么导致了下面的问题。我能够创建并保留一个 B 类型的对象，该对象具有父 A (@Parent) 并具有 C 类型的嵌入对象。当我尝试编辑该对象时，尽管出现以下错误。什么会导致这个错误？
public class A extends DatastoreObject<Long>{
@Id private Long id;
@Override
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
}
public class C extends ValueProxy{
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
public class B extends DatastoreObject<Long>{
@Id private Long id;
@Parent public Key<A> a;
public String label;
@Embedded
public C c;
@Override
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getLabel() {
return label;
}
public void setLabel(String label) {
this.label = label;
}
public A getA(){
if (a == null) {
return null;
}
try {
return new ADAO().get(a);
} catch (NotFoundException e){
return null;
}
}
public void setA(A a) {
this.a = new ADAO().key(a);
}
public void setCustomer(Key<A> a){
this.a = a;
}
public C getC(){
return c;
}
public void setC(C c){
this.c = c;
}
}
private void updateSite(String label){
BRequest bRequest = requestFactory.bRequest();
BProxy b = bRequest.edit(bToEdit); //bToEdit is set when I get the object earlier
b.setLabel("something");
siteRequest.persist(b);
siteRequest.fire(...);
}
com.google.web.bindery.requestfactory.server.RequestFactoryServlet doPost
SEVERE: Unexpected error
java.lang.IllegalArgumentException: argument type mismatch
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:104)
at com.google.web.bindery.requestfactory.server.ReflectiveServiceLayer.setProperty(ReflectiveServiceLayer.java:234)
at com.google.web.bindery.requestfactory.server.ServiceLayerDecorator.setProperty(ServiceLayerDecorator.java:193)
at com.google.web.bindery.requestfactory.server.ServiceLayerDecorator.setProperty(ServiceLayerDecorator.java:193)
at com.google.web.bindery.requestfactory.server.ServiceLayerDecorator.setProperty(ServiceLayerDecorator.java:193)
at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor$1.visitReferenceProperty(SimpleRequestProcessor.java:529)
at com.google.web.bindery.autobean.vm.impl.ProxyAutoBean.traverseProperties(ProxyAutoBean.java:324)
at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.traverse(AbstractAutoBean.java:166)
at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.accept(AbstractAutoBean.java:101)
at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.processOperationMessages(SimpleRequestProcessor.java:516)
at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:210)
at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:127)
at com.google.web.bindery.requestfactory.server.RequestFactoryServlet.doPost(RequestFactoryServlet.java:133)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at com.google.inject.servlet.ServletDefinition.doService(ServletDefinition.java:263)
at com.google.inject.servlet.ServletDefinition.service(ServletDefinition.java:178)
at com.google.inject.servlet.ManagedServletPipeline.service(ManagedServletPipeline.java:91)
at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:62)
at com.google.inject.servlet.ManagedFilterPipeline.dispatch(ManagedFilterPipeline.java:118)
at com.google.inject.servlet.GuiceFilter.doFilter(GuiceFilter.java:113)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:35)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:60)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:122)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.BackendServersFilter.doFilter(BackendServersFilter.java:97)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:78)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:363)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)