cascading dropdown in primefaces 3.2 not working

Question

i wish to use cascading dropdown in primefaces 3.2 but its not working. below is my xhtml code:

<p:selectOneMenu style="width: 150px" value="#{watchBean.exchange}">
                    <f:selectItem itemLabel="NSE" itemValue="nse"/>
                    <f:selectItem itemLabel="BSE" itemValue="bse"/> 
                    <p:ajax event="change" update="sym" listener="#{watchBean.wow}" />
                </p:selectOneMenu> 
            <p:selectOneMenu style="width: 150px" id="sym" value="#{watchBean.sl}" var="scrip">
                <f:selectItems  itemLabel="#{scrip.scripSymbol}" itemValue="#{scrip.scripSymbol}"/>
            </p:selectOneMenu> 

bean code:

import java.util.List;
import javax.annotation.ManagedBean;
import javax.inject.Named;
import javax.enterprise.context.RequestScoped;
import javax.faces.context.FacesContext;
import javax.faces.event.ValueChangeEvent;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.xml.ws.WebServiceRef;
import service.MasterScrip;
import service.StatelessWebService_Service;

/**
 *
 * @author root
 */
@javax.faces.bean.ManagedBean
@javax.faces.bean.RequestScoped
public class watchBean {
    @WebServiceRef(wsdlLocation = "WEB-INF/wsdl/localhost_8080/StatelessWebService/StatelessWebService.wsdl")
    private StatelessWebService_Service service;

    /** Creates a new instance of watchBean */
    public watchBean() {
    }
    String uname,scripSym,exchange;
    Integer scripID;
    List<UserTrack> ut;
List<MasterScrip> sl;
    public List<MasterScrip> getSl() {
        return sl;
    }

    public void setSl(List<MasterScrip> sl) {
        this.sl = sl;
    }


    public String getExchange() {

        return exchange;
    }

    public void setExchange(String exchange) {
        sl=getAllScripByExchange(exchange);
        setSl(sl);
        this.exchange = exchange;
    }
public void wow(ValueChangeEvent e)
{    
    sl=getAllScripByExchange((String)e.getNewValue());
   // setSl(sl);
    //FacesContext.getCurrentInstance().renderResponse();

    // sl=getAllScripByExchange(exchange);
} ....

i get the following error:

javax.el.MethodNotFoundException: Method not found: beans.watchBean@2e1b13.wow(javax.faces.event.AjaxBehaviorEvent)

i referred to How do I get PrimeFaces <p:selectOneMenu> to call valueChangeListener? and removed the listener from my code, kept only the value attribute for 1st dropdown,still it doesnt work, then it gives no error and the 2nd dropdown isnt filled dynamically. i am stuck in this, what is the cause of this error and how can it be solved?

Answer 1

1) Remove parameter from method wow(). the ajax listener takes no parameter; when the method is executed, the attribute "exchange" contains the new value.
2) the selectOneMenus should be surrounded by h:form
3) The second selectOneMenu is wrong. the value attribute of the selectOneMenu should reference the selected item of the combo; not the list of items. the var attribute goes in the f:selectItems tag. the f:selectItems tag is missing the value attribute, which references the list of items. it should look like this:

<p:selectOneMenu style="width: 150px" id="sym" value="#{watchBean.selectedItem}" >
          <f:selectItems value="#{watchBean.sl}" var="scrip"
                         itemLabel="#{scrip.scripSymbol}"
                         itemValue="#{scrip.scripSymbol}"/>
</p:selectOneMenu>