HOWTO: command_button, action and request parameters HOWTO

Question

Starting from carDetail.jsp example:
Click of button:
<h:command_button
action="#{carstore.storeFrontLuxuryPressed}"
value="#{bundle.moreButton}" >
</h:command_button>
Method Invoked:
public String storeFrontLuxuryPressed() {
     setCurrentModelName("Luxury");
     return "carDetail";
Navigation case "carDetail" maps to:
<navigation-rule>
<from-view-id>/storeFront.jsp</from-view-id>
<navigation-case>
<description>
Any action that returns "carDetail" on storeFront.jsp should
cause navigation to carDetail.jsp
</description>
<from-outcome>carDetail</from-outcome>
<to-view-id>/carDetail.jsp</to-view-id>
</navigation-case>
</navigation-rule>
So I imagine that a forward is done to carDetail.jsp
At this point I want to daviate from the sample. I would like to pass request parameters to carDetail.jsp
like:
carDetail.jsp?mode=create&date=25-Dec-2003
I want my managed bean in carDetail.jsp to get populated from request scope. The managed bean in config looks something like this:
<managed-bean>
<description>this is for item test bean.</description>
<managed-bean-name>PageParams </managed-bean-name>
<managed-bean-class> com.a.PageParams</managed-bean-class>
<managed-bean-scope> request </managed-bean-scope>
<managed-property>
<property-name>mode</property-name>
<value>#{requestScope.mode}</value>
</managed-property>
<managed-property>
<property-name>date</property-name>
<value>#{requestScope.date}</value>
</managed-property>
</managed-bean>
How should I code the following method to pass the request parameters to the next page:
public String storeFrontLuxuryPressed() {
     setCurrentModelName("Luxury");
//Can I do anything here to help navigation system to pass additional request parameters to
//the carDetail.jsp page
     return "carDetail";
Please help as I have many pages that have command_button and control leads to other pages that take request parameters to initialize and set themselves up. And I can't understand how to make the two concepts work together?
Thanks,
Vinay

Answer 1

Thx hunangdp
your solution of using <f:parameter> is perfect #in case# <h:command_button> is not nested inside <h:data_table> , otherwise the request parameter passed will always show the value of the 1st row , not the clicked row .
consider the following :
<h:data_table var="item" value="#{shoppingCartBean.shoppingItems}" >
<h:column>
<h:command_link value="#{item.productId}" action="product" id="productAction">
<h:output_text value="#{item.productName}"/>
<f:parameter name="productId" value="#{item.productId}"/>
</h:command_link>
</h:column>
</h:data_table>
in this case using the following at the back end :
FacesContext fc = FacesContext.getCurrentInstance();
java.util.Map requestParameter = fc.getExternalContext().getRequestParameterMap();
String value = requestParameter.get("productId");
will return the value of the 1st row ..
so if, instead I consider adding an action listener which set the request attribute "productId" to the command_link value , this will work , but I have to get the value from request attribute not the request parameter ==> :
<h:data_table var="item" value="#{shoppingCartBean.shoppingItems}"
rowClasses="InnerTable">
<h:column>
<h:command_link value="#{item.productId}" action="product" id="productAction">
<h:output_text value="#{item.productName}"/>
<f:action_listener type="mybean.Listener"/-->
</h:command_link>
</h:column>
</h:data_table>
and mybean.listener ==> :
String id = (String) ((UICommand) event.getComponent()).getValue();
HttpServletRequest request = (HttpServletRequest)facesContext.getExternalContext().getRequest();
request.setAttribute("productId", id);
any comments.. ?