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From "G.L. Grobe" <>
Subject Re: WebWorkVelocityServlet
Date Thu, 11 Jul 2002 02:58:09 GMT
Ok, I understand this part now. What I don't get is how to have my action
(which is now a WebWorkVelocityServlet since I've changed the class it's
extended from) decide which view to return depending upon the query string
param coming in from the template page.

Below is my original action where I would compare the values of 'view' and
return a view mapping pending the value of view ...

public class Products extends ActionSupport implements ParameterAware {
   private Map params;
   public void setParameters(Map map) { this.params = map; }

   public String doExecute() throws Exception {

      if (view.equals("myview.a")) {
         return "selectA.success";
      else if (view.equals("myview.b")) {
         return "selectB.success";

      return "select.error";

Then I needed to capture the parameter from within the action (coming from
the velocity *.vm template) so I changed the class I extended from and now
have ...

public class Products extends WebWorkVelocityServlet implements
ParameterAware {
   private Map params;
   public void setParameters(Map map) { this.params = map; }

// since this is already in the VelocityServlet, it no longer exists in here
/*   public Template handleRequest(Context context) { ... */

   // but I no longer have the doExecute() I had above to decide which view
to return
   // based on the incoming parameter

As I understand it, I now have the handleRequest() method so that I can get
a query string parameter from the servlet now and write something like this
in the template page ...
--- *.vm file
   #if ( $reqParser.getParameter("myParam").equals("this_string") )
      ## do something

The problem is that whereas I had the execute() method from the first
ex.(extended from ActionSupport) to compare views and return a different
view pending on the value of view, I don't know how to do this (return views
pending a query string parameter in the servlet request) w/ the

So what I have is a query string coming from the template to the action, and
then I'll return a view mapping w/ query string parameters back to the
browser depending on the value of the incoming query string param.

I hope I explained it clearly. Thanks for your responses.

----- Original Message -----
From: "Bill Burton" <>
To: "Velocity Users List" <>
Sent: Wednesday, July 10, 2002 7:56 PM
Subject: Re: [off topic] WebWorkVelocityServlet

> Hello,
> Part of these questions are rather general to Velocity not too WebWork
> specific so I'll try and answer them here ...
> "G.L. Grobe" wrote:
> #snip()
> The WebWorkVelocityServlet extends VelocityServlet.  As a result it also
> exposes the HttpServletRequest object in the Velocity context as $req.  So
> there's nothing extra you need to do to access request parameters within a
> Velocity template--just call $req.getParameter("foo") or whatever methods
> you want to call.
> With code below, a NullPointerException would be thrown if myParam doesn't
> exist.
> > By using this, I understand that I can write the following in my
> > templates ...
> >
> >    #if ( $reqParser.getParameter("myParam").equals("this_string") )
> >       ## do something
> >    #end
> Instead, do this ...
>     #if ( $req.getParameter("myParam") == "this_string" )
>         ## do something
>     #end
> -Bill
> --
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