You may have an existing JSP (or Struts, Spring MVC, etc.) application that you want to migrate to Tapestry. It's quite common to do this in stages, moving some functionality into Tapestry and leaving other parts, initially, in the other system.

How do I may a form on a JSP submit into Tapestry?

Tapestry's Form component does a lot of work while an HTML form is rendering to store all the information needed to handle the form submission in a later request; this is all very specific to Tapestry and the particular construction of your pages and forms; it can't be reproduced from a JSP.

Fortunately, that isn't necessary: you can have a standard HTML Form submit to a Tapestry page, you just don't get to use all of Tapestry's built in conversion and validation logic.

All you need to know is how Tapestry converts page class names to page names (that appear in the URL). It's basically a matter of stripping off the root-package.pages prefix from the fully qualified class name. So, for example, if you are building a login screen as a JSP, you might want to have a Tapestry page to receive the user name and password. Let's assume the Tapestry page class is com.example.myapp.pages.LoginForm; the page name will be loginform ¹ , and the URL will be /loginform.

<form method="post" action="/loginform">

  <input type="text" value="userName"/>
  <br/>
  <input type="password" value="password"/>
  <br/>
  <input type="submit" value="Login"/>

</form>

On the Tapestry side, we can expect that the LoginForm page will be activated; this means that its activate event handler will be invoked. We can leverage this, and Tapestry's RequestParameter annotation:

public class LoginForm
{
  void onActivate(@RequestParameter("userName") String userName, @RequestParameter("password") String password)
  {
     // Validate and store credentials, etc.
  }
}

The RequestParameter annotation extracts the named query parameter from the request, coerces its type from String to the parameter type (here, also String) and passes it into the method.

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1. Tapestry is case insensitive, so LoginForm would work just as well. ↩