Send p:autoComplete value as a param in JSF - jsf

Question

i have a rare situation in my page i have a "p:autoComplete" which is bind to a backing bean i can read that auto complete item form the backing bean.
but the problem is the selected value from that auto complete need to be passed as a parameter, when user pressed the button, with some other parameters. which i really don't know how to do it?
this is my page which has the autocomplete
<p:panel header="Employee sales" style="width:500px"
toggleable="true" toggleSpeed="500" closeSpeed="500">
<p:autoComplete id="user_auto_complete"
value="#{salesReportMainController.userFromAutoComplete}"
completeMethod="#{salesReportMainController.completeUser}"
var="user" itemLabel="#{user.userName}" itemValue="#{user}"
converter="#{userConverter}" forceSelection="true" />
<p:commandButton id="Search" value="Generate"
action="admin_common_barchart">
<f:param name="todaysDate"
value="#{salesReportMainController.todaysDate}" />
<f:param name="beforDate"
value="#{salesReportMainController.dateBeforOneYear}" />
<f:param name="employeeName"
value="#{salesReportMainController.userFromAutoComplete.userName}" />
</p:commandButton>
</p:panel>
and this is the backing bean that binds to that page
#ViewScoped
public class SalesReportMainController implements Serializable{
private static final long serialVersionUID = 1L;
#ManagedProperty(value = "#{userService}")
public UserService userService;
public DateTime todaysDate;
public DateTime dateBeforOneYear;
public DateTime dateBeforsixMonths;
public List<User> allUsers;
public List<User> acFilterdUsers;
public User userFromAutoComplete;
#PostConstruct
public void init(){
int oneYear = ConstantConfiguration.YearsInMonths.ONE_YEAR.getValue();
int sixMonths = ConstantConfiguration.YearsInMonths.SIX_MONTH.getValue();
todaysDate = new DateTime();
dateBeforOneYear = new DateTime(todaysDate).minusMonths(oneYear);
dateBeforsixMonths = new DateTime(todaysDate).minusMonths(sixMonths);
}
// public String buttonClick(){
// System.out.println("aaaaaaaa");
// return null;
// }
public List<User> completeUser(String query) {
allUsers = userService.getAllUsers();
acFilterdUsers = new ArrayList<User>();
for (User user : allUsers) {
if(user.getUserName().toLowerCase().startsWith(query)){
acFilterdUsers.add(user);
}
}
return acFilterdUsers;
}
public String getAutoCompleteUser() {
if (userFromAutoComplete != null) {
//i can get the value of the selected item form auto complete
}
return null;
}
//getters and setters
}
and this is the page that i want to load
<h:form id="common_chart_form" prependId="flase">
<p:growl id="growl" showDetail="true" autoUpdate="true"
sticky="false" />
<p:outputLabel id="labelvalue" value="aaaaaaaaaa"/>
<p:chart id="chart" type="bar"
model="#{commonChartController.barModel}" style="height:600px" />
<p:commandButton value="Print" type="button" icon="ui-icon-print">
<p:printer target="chart" />
</p:commandButton>
<p:commandButton value="Back" action="admin_sales_reports" />
</h:form>
and this the backing bean of the above page
#Component
#ManagedBean
#RequestScoped
public class CommonChartController implements Serializable{
private static final long serialVersionUID = 1L;
#ManagedProperty(value = "#{orderService}")
public OrderService orderService;
#ManagedProperty(value = "#{userService}")
public UserService userService;
List<MonthSales> salesList;
private BarChartModel barModel;
#PostConstruct
public void init() {
String dateTo = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("todaysDate");
String dateFrom = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("beforDate");
String employeeName = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("employeeName");
System.out.println("user Name : "+employeeName);
if(employeeName != null && !employeeName.equals("")){
User user = userService.getUserByUserName("admin");
salesList = orderService.getMonthlySalesByUserName(UserUtility.stringDateToJodaDateTime(dateFrom).toDate(), UserUtility.stringDateToJodaDateTime(dateTo).toDate(), user);
createBarModel(salesList, user);
}else {
salesList = orderService.getMonthlySales(UserUtility.stringDateToJodaDateTime(dateFrom).toDate(), UserUtility.stringDateToJodaDateTime(dateTo).toDate());
createBarModel(salesList);
}
//
// salesList = orderService.getMonthlySales(UserUtility.stringDateToJodaDateTime(dateFrom).toDate(), UserUtility.stringDateToJodaDateTime(dateTo).toDate());
// createBarModel(salesList);
}
}
i can read the "dateTo" param and "dateFrom" param. problem is "employeeName" param is alwayas null