Question

Is there a way to display a specific JSF page based on the request URL?

Let’s say I have a JSF page “details.xhtml“. The managed bean “detailsBean” has a list of objects where each object has its own ID. Now if a user requests the page “../details.xhtml?id=1“, the list should be queried for an object with ID 1 and the resulting details page of this object should be displayed.

I already wrote a converter implementation class which can convert from object to ID and vice versa, but I don’t know how to use it properly. Do I have to work through the JAX-RS specification for this to work or is there a more simple solution?

Answer 1

You can achieve this with plain JSF with the following steps

1. Capture the ID in the request to determine what object is being queried for in your DetailsBean from the request parameter. There are many ways to achieve this, one of which is adding the following annotation to your managed bean (this is currently only permitted for a @RequestScoped bean, see why here).

      @ManagedProperty(value="#{param.id}")
      int requiredObjectId;
   

   The annotation above will capture the id parameter from the request and assign it to the requiredObjectId variable.

2. Using the captured Id, setup your object in your bean in a @PostConstruct method

      @PostConstruct
      public void queryForObject(){
   
      //use the requiredObjectId variable to query and setup the object in the backing bean
   
      }
   

   The object retrieved should be assigned as an instance variable of your managed bean

3. In your view, you could then reference the queried object that has been setup in the backing bean

     <h:panelGrid columns="2">
        <h:outputText value="Title"/>
        <h:outputText value="#{detailsBean.selectedObject.title}"/>
     </h:panelGrid>
   

If your bean is in a scope broader than the request scope, you’ll need a combination of constructs to cleanly pull that request parameter before view rendering.

1. Capture the request parameter within the JSF view itself using

   <f:metadata>
    <f:viewParam name="id" value="#{detailsBean.requiredObjectId}" required="true" requiredMessage="You must provide an Object Id"/>         
   </f:metadata>
   
       **OR**
   

2. Due to the nature of JSF Lifecycle processing, doing the above alone may not make the value available for your use in time for object setup. You could use the following instead.

    <f:metadata>
       <f:event type="preRenderView" listener="#{detailsBean.setObjectId}" />         
   </f:metadata>
   

   What we’ve done here is specify a method (that captures the id) in the backing bean that must be executed before the view is rendered, ensuring that the id parameter is available as at the time you need it. Proceed with step 3, only if you’re using <f:event/> above.

3. In the backing bean, you now define the setObjectId method

     public void setObjectId(){
   
     Map<String,String> requestParams =      FacesContext.getExternalContext().getRequestParameterMap();
     requiredObjectId =  Integer.parseInt(requestParams.get("id"));
   
     }
   

Note that the above option is generally a work around/hack and not a clean solution as such