Problem with @Reference if referenced object is null

[GoogleCodeExporter]

If I have a object like this:

@Entity
public class Test {
@Id
private ObjectId id;

@Reference
private Test2 test2;

@Reference
private Test3 test3;

// constructor, getters, setters etc

}

And try to save a Test object, with the test2 object null (schemaless), Morphia 
throws a MappingException, because the test2 id is null.

That's very, very sad.

Thanks.

Original issue reported on code.google.com by caarlos0 on 25 Aug 2011 at 6:07

[GoogleCodeExporter]

Morphia doesn't save null for missing fields. How did this get it in there? Or 
was it during loading?

You can ignore bad refs using this (see below), but I doubt it will fix this 
problem. Please pose the full stack-trace.

@Reference(ignoreMissing=true)

Original comment by scotthernandez on 25 Aug 2011 at 7:08

[GoogleCodeExporter]

com.google.code.morphia.mapping.MappingException: Error mapping 
field:br.com.digitaldoc.eatos.server.persistencia.mongo.pojos.UsuarioPojo.prefei
tura
    at com.google.code.morphia.mapping.Mapper.toDBObject(Mapper.java:444)
    at com.google.code.morphia.mapping.Mapper.toDBObject(Mapper.java:426)
    at com.google.code.morphia.DatastoreImpl.entityToDBObj(DatastoreImpl.java:674)
    at com.google.code.morphia.DatastoreImpl.save(DatastoreImpl.java:722)
    at com.google.code.morphia.DatastoreImpl.save(DatastoreImpl.java:793)
    at com.google.code.morphia.DatastoreImpl.save(DatastoreImpl.java:787)
    at com.google.code.morphia.dao.BasicDAO.save(BasicDAO.java:109)
    at br.com.digitaldoc.eatos.server.persistencia.mongo.dao.DaoUsuario.salvar(DaoUsuario.java:41)
    at br.com.digitaldoc.eatos.server.persistencia.mongo.dao.DaoUsuario.salvar(DaoUsuario.java:1)
    at br.com.digitaldoc.eatos.server.services.UsuarioServiceImpl.salvar(UsuarioServiceImpl.java:23)
    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 com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:205)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)
Caused by: com.google.code.morphia.mapping.MappingException: @Id field cannot 
be null!
    at com.google.code.morphia.mapping.ReferenceMapper.getKey(ReferenceMapper.java:118)
    at com.google.code.morphia.mapping.ReferenceMapper.writeSingle(ReferenceMapper.java:51)
    at com.google.code.morphia.mapping.ReferenceMapper.toDBObject(ReferenceMapper.java:45)
    at com.google.code.morphia.mapping.Mapper.writeMappedField(Mapper.java:529)
    at com.google.code.morphia.mapping.Mapper.toDBObject(Mapper.java:442)
    ... 36 more

Original comment by caarlos0 on 25 Aug 2011 at 8:02

[GoogleCodeExporter]

@Reference(ignoreMissing=true) doesn't work...
I'am usign morphia 0.99, don't know if it matters...

Original comment by caarlos0 on 25 Aug 2011 at 8:04

[GoogleCodeExporter]

You need to set the @Id field for the referenced entities before you call save.

Caused by: com.google.code.morphia.mapping.MappingException: @Id field cannot 
be null!

Original comment by scotthernandez on 25 Aug 2011 at 10:30

• Changed state: Invalid

[GoogleCodeExporter]

but I don't want to save the reference, because the entire reference (Test2) is 
null. When the reference is null, morphia should just ignore it (schemeless).

I don't want to save a empty bean.

Original comment by caarlos0 on 25 Aug 2011 at 11:37

[GoogleCodeExporter]

The code seems pretty clear, if you pass in a null then you won't get this 
error (or get far enough to cause this error). The error occurs if you pass an 
entity without an @Id value. If you have a test case to show otherwise I can 
add it to the tests.

Here is the code (where a NPE will happen if entity is null): 
                        MappedClass mappedClass = mapr.getMappedClass(entity);
            Object id = mappedClass.getIdField().get(entity);
            if (id == null)
                throw new MappingException("@Id field cannot be null!");

Original comment by scotthernandez on 25 Aug 2011 at 11:53