twig 1.0.4 - problem with loading blob

[ghost23]

hello,

i have a problem with loading an object from the datastore, that has a
blob. This is my class:

package com.bookletona.users;

import java.io.Serializable;
import com.google.appengine.api.datastore.Blob;
import com.vercer.engine.persist.annotation.Embed;
import com.vercer.engine.persist.annotation.Index;
import com.vercer.engine.persist.annotation.Store;

@SuppressWarnings("serial")
public class User implements Serializable, Comparable<User> {

@Store(false) private String generatedKey;

@Index private String eMail;
private String firstName;
@Index private String lastName;
@Embed private Blob image;
private String[] tags;

public User(){

}
}

Now, saving this works without problems, i can see the object via the
Datastore viewer. But when i want to load the object again,
i get an exception:

java.lang.IllegalStateException: Problem translating field private
com.google.appengine.api.datastore.Blob
com.bookletona.users.User.image
at
com.vercer.engine.persist.translator.ObjectFieldTranslator.activate(ObjectFieldTranslator.java:
111)
at com.vercer.engine.persist.standard.StrategyObjectDatastore
$2.activate(StrategyObjectDatastore.java:222)
at
com.vercer.engine.persist.translator.ObjectFieldTranslator.propertiesToTypesafe(ObjectFieldTranslator.java:
56)
at
com.vercer.engine.persist.standard.AbstractStatelessObjectDatastore.toTypesafe(AbstractStatelessObjectDatastore.java:
273)
at
com.vercer.engine.persist.standard.StrategyObjectDatastore.toTypesafe(StrategyObjectDatastore.java:
504)
at com.vercer.engine.persist.standard.StandardTypedFindCommand
$EntityToInstanceFunction.apply(StandardTypedFindCommand.java:572)
at com.vercer.engine.persist.standard.StandardTypedFindCommand
$EntityToInstanceFunction.apply(StandardTypedFindCommand.java:560)
at com.google.common.collect.Iterators$8.next(Iterators.java:697)
at
com.google.common.collect.ForwardingIterator.next(ForwardingIterator.java:
43)
at com.google.common.collect.Sets.newHashSet(Sets.java:223)
at
com.bookletona.users.server.UserAdapter.queryUsers(UserAdapter.java:
130)
at com.bookletona.users.server.UserResource.doGet(UserResource.java:
69)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:
511)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1166)
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:362)
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.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
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)
Caused by: java.lang.ClassCastException: [B cannot be cast to
[Ljava.lang.Object;
at
com.vercer.engine.persist.conversion.CollectionConverter.createCollectionInstance(CollectionConverter.java:
151)
at
com.vercer.engine.persist.conversion.CollectionConverter.convert(CollectionConverter.java:
111)
at
com.vercer.engine.persist.conversion.CombinedTypeConverter.convert(CombinedTypeConverter.java:
37)
at
com.vercer.engine.persist.conversion.DefaultTypeConverter.convert(DefaultTypeConverter.java:
56)
at
com.vercer.engine.persist.translator.ObjectFieldTranslator.activate(ObjectFieldTranslator.java:
127)
at com.vercer.engine.persist.standard.StrategyObjectDatastore
$2.activate(StrategyObjectDatastore.java:222)
at
com.vercer.engine.persist.translator.ObjectFieldTranslator.propertiesToTypesafe(ObjectFieldTranslator.java:
56)
at
com.vercer.engine.persist.translator.ListTranslator.propertiesToTypesafe(ListTranslator.java:
48)
at
com.vercer.engine.persist.translator.ObjectFieldTranslator.activate(ObjectFieldTranslator.java:
106)

[ghost23]

hello,

after trying out various things, i could solve the problem by myself.

I changed:

@Embed private Blob image;

to:

@Type(Blob.class) private Blob image;

Now it works, although i am not completely sure, why. The type of the
field is Blob,
why do i have tell twig again, that this is a Blob?!