问Flex : LCDS服务在第二次执行时返回null Asynctoken

EN

 var token:AsyncToken = services.requestService.commit(new Array(model.currentRequestDetail));
 responder = new AsyncResponder(resultHandler, faultHandler, token);
 if ( token ) token.addResponder(responder);

[Managed]
[RemoteClass(alias="be.fgov.mobilit.td.lcds.vo.RequestDetail")]
public class RequestDetail {

    public var id:Number;
    public var request:Request;
    public var task:Task;

    /**
     * Constructor
     */
    public function RequestDetail() {
    }
}

var requestDetailService:DataService = new DataService("requestDetail");
requestDetailService.autoCommit = false;

resultHandler(result:Object, token:Object = null)
faultHandler(result:Object, token:Object = null)

package be.fgov.mobilit.td.lcds.assemblers;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import be.fgov.mobilit.td.lcds.vo.RequestDetail;
import flex.data.ChangeObject;
import flex.data.assemblers.AbstractAssembler;

public class RequestAssembler extends AbstractAssembler {

public RequestAssembler() {
    // TODO Auto-generated constructor stub
}

public RequestDetail getRequest(Map<String, Object> identity) {
    return ServiceUtility.getLcdsService().getRequestDetail(identity);
}

public List<ChangeObject> syncRequest(List<ChangeObject> changes) {
    Iterator<ChangeObject> iterator = changes.iterator();
    ChangeObject co;
    while (iterator.hasNext()) {
        co = (ChangeObject) iterator.next();
        if (co.isUpdate()) {
            co = doUpdate(co);
        }
    }
    return changes;
}

private ChangeObject doUpdate(ChangeObject co) {
    RequestDetail requestDetail = (RequestDetail) co.getNewVersion();
       co.setNewVersion(ServiceUtility.getLcdsService().updateRequestDetail(requestDetail));
    return co;
}
}

<destination id="request">
    <properties>
<source>be.fgov.mobilit.td.lcds.assemblers.RequestAssembler</source>

        <scope>application</scope>

        <metadata>
            <identity property="id" />
            <identity property="task" />
        </metadata>

        <server>
            <get-method>
                <name>getRequest</name>
            </get-method>
            <sync-method>
                <name>syncRequest</name>
            </sync-method>
        </server>
    </properties>
</destination>

package be.fgov.mobilit.services {
import mx.data.DataService;
import mx.messaging.Consumer;
import mx.messaging.events.MessageEvent;
import mx.rpc.http.HTTPService;

public class LiveCycleServices {

    public var requestService:DataService;

    public function LiveCycleServices() {           

        requestService  = new DataService("request");
        requestService.autoCommit = false;
    }


    /**
     * @param   MessageEvent    The event object that is dispatched by the Flex framework
     * @return  void
     * 
     * This message captures the server push messages that need to trigger an update
     * of the task list, since this is specific for every client and cannot be 
     * determined on the server side, coming from LiveCycle.
     */
    private function messageHandler(event:MessageEvent):void {
        taskListService.refresh();          
    }
}
}

var token:AsyncToken = services.requestService.commit(new   Array(model.currentRequestDetail));
var responder:AsyncResponder = new AsyncResponder(resultHandler, faultHandler, token);
if ( token ) token.addResponder(responder);