Changing assigned user in sql using SelectOneMenu primeface : I have been searching for similar issue but I could not find any. 
so here is the thing

I am trying to create a web application that deals with HR stuff, like employee requests (Resign, loan, vacation, etc..) 
I am using primeface and I have the following problem that I cant figure out. 

The thing is I am trying to do is :
1- When user first creates the request and assigns the user and submit the form
the next step is
2- the manager would sees the request and then change the "Person responsible for the request" to a new one using the drop menu in the datatable and I have been trying to solve this problem with no luck.
 Here is the dialog script


            <h:form id='resignf'>
                        <p:dialog id='res' header="Resign Request" widgetVar="resign" minHeight="40">

                                <p:outputLabel value="Employee name" /> 
                                <p:inputText value="#{controller.resignName}" required="true" requiredMessage="This field is required" />

                                <p:outputLabel value="Employee Number" /> 
                                <p:inputText value="#{controller.resignEmployeNum}" required="true" />

                               
                                <p:inputText value{controller.resignNationalIDNum}" required="true"  />

                                
                                <p:inputText value="#{controller.resignNotes}" required="true"  />

                                <p:outputLabel for="AssignUser" value="User" /> 

                                <p:selectOneMenu id="AssignUser"  value="#{controller.assignUser}" style="width:150px" converter="UConverter">
                                    <f:selectItems value="#{controller.usersList}"  var="user" itemLabel="#{user.username}"/>



                                </p:selectOneMenu >





                                <p:commandButton action="#{controller.createResignRequest()}" onclick="PF('resign').hide();" update="@all"/>

                            </p:panelGrid>


                        </p:dialog>


And the code is my `controller.java` file below to create the request in the table

    /* Request to resign*/
    private List<ResignationRequest> resignList;
    private ResignationRequestController rController = new ResignationRequestController();

    private String resignName;
    private String resignEmployeNum;
    private String resignNationalIDNum;
    private String ResignNotes;
    private int AutoAssignToIDNUM;

    /* end of request to resign*/

        public void createResignRequest() {

        System.out.println("createResignRequest");
        ResignationRequest newResign = new ResignationRequest();

        newResign.setName(resignName);
        newResign.setEmployeeNum(resignEmployeNum);
        newResign.setNationalID(resignNationalIDNum);
        
        newResign.setNotes(ResignNotes);

        newResign.setUserID(AssignUser);
        
        rController.create(newResign);
        resignList = rController.findResignationRequestEntities(); //retrieves all the resigns from the database

    }

Now all that is working perfectly, but when I try to change the old user with the new one here I get confused! so far what I have been thinking is I need to find the old user and then switch him, but I could not figure a way to do it using the select list. The script for for changing the "User responsible for the request" below

    
      <p:dataTable id="resignTable1" cellSeparator="true" editMode="cell" editable="true"  var="resign" value="#{controller.resignList}" paginator="true"    rows="10" rowIndexVar="index1">
                            <p:ajax id="aj" event="cellEdit" listener="#{controller.editUser(user)}" update="resignTable1"/>

                            <p:column headerText="Employee number">
                                <p:cellEditor>
                                    <f:facet name="output"> <h:outputText value="#{resign.employeeNum}" /></f:facet>
                                    <f:facet name="input"> <h:inputText value="#{resign.employeeNum}" /></f:facet>

                                </p:cellEditor>
                            </p:column>
                            <p:column headerText="name">
                                <p:cellEditor>
                                    <f:facet name="output"> <h:outputText value="#{resign.name}" /></f:facet>
                                    <f:facet name="input"> <h:inputText value="#{resign.name}" /></f:facet>

                                </p:cellEditor>
                            </p:column>



                            <p:column headerText="Request Number">
                                <p:cellEditor>
                                    <f:facet name="output"> <h:outputText value="#{resign.id}" /></f:facet>
                                    <f:facet name="input"> <h:inputText value="#{resign.id}" /></f:facet>

                                </p:cellEditor>
                            </p:column>

                            <p:column headerText="User responsible for the request">
                                <p:cellEditor>
                                    <f:facet name="output"> <h:outputText value="#{resign.userID}" /></f:facet>
                                    <f:facet name="input"> <h:inputText value="#{resign.userID}" /></f:facet>

                                </p:cellEditor>
                            </p:column>


                            <p:column headerText="Comments">
                                <p:cellEditor>
                                    <f:facet name="output"> <h:outputText value="#{resign.notes}" /></f:facet>
                                    <f:facet name="input"> <h:inputText value="#{resign.notes}" /></f:facet>

                                </p:cellEditor>
                            </p:column>


                            <p:column headerText="Send the request to the next employee">

                              
                                <p:selectOneMenu id="AssignUser"  value="#{controller.assignUser}" style="width:150px" converter="UConverter" onchange="submit();">
                                    <f:selectItems value="#{controller.usersList}"  var="user" itemLabel="#{user.username}"   actionListener="#{controller.editRequestStep(resign)}"  >

                                        

                                        </f:selectItems>





                                    </p:selectOneMenu >

In my controller file

  

        public void editRequestStep(ResignationRequest r) {
        
        System.out.println("Edit resign");
        
        try {
            System.out.println("Edit resign");
            rController.edit(r);
            
        } catch (Exception ex) {
            Logger.getLogger(Controller.class.getName()).log(Level.SEVERE, null, ex);
        }

    }


I tried to get as much as I could from the code but I have a lot of stuff that I am not sure if I should submit. I tried ajax

NOTE: I am using mySQL, apache tomcat in case if it matters.