3.9. Generating Dynamic Select List Options
Problem
You want to dynamically change the options displayed in a
select element based on a change in another field
in the same form, without having to render the set of options in
client-side JavaScript.
Tip
This problem isn't about avoiding JavaScript altogether; instead, it shows how to call a Struts action from a client-side JavaScript event listener.
Solution
Use an onchange or onclick
JavaScript listener to call a JavaScript function that submits the
form to a Struts Action. In the
Action, perform the necessary business logic to
construct a new collection for the select options,
and forward control back to the original JSP page. Example 3-11 shows a JSP page that submits the form to an
Action when the user clicks a radio button. The
value of the radio button is passed to the Action
as a request parameter.
Example 3-11. Submitting a form using JavaScript
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %> <%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %> <html> <head> <title>Struts - JavaScript Example</title> <script language="JavaScript"> function getOptions(control) { form = control.form; form.action = "SetOptions.do?someProp="; form.action += control.value; form.submit( ); } </script> </head> <body> <html:form action="ProcessMyForm"> <html:radio property="someProp1" value="val1" onclick="getOptions(this);"/> Value 1<br/> <html:radio property="language" ...Get Jakarta Struts Cookbook now with the O’Reilly learning platform.
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