Donald put this attachment on one of his posts. It's quite helpful and I've
attached it again to this message.
Dave
>From: "John Averty" <[EMAIL PROTECTED]>
>Reply-To: "John Averty" <[EMAIL PROTECTED]>
>To: "Struts Users Mailing List"
><[EMAIL PROTECTED]>,<[EMAIL PROTECTED]>
>Subject: Re: Dynamic number of form fields
>Date: Wed, 11 Sep 2002 14:47:18 -0700
>
>I'm na new struts user, and I'm trying to get a true dynamic form to work.
>Could you give me more pointers on how to access this doc?
>
>Thanx,
>
>John
>
>----- Original Message -----
>From: "Donald Ball" <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
>Sent: Wednesday, September 11, 2002 10:34 AM
>Subject: Re: Dynamic number of form fields
>
>
>
> > The Dyna beans don't exactly give you what you're looking for. The
> > properties of a Dyna bean must be known at deployment time, do they're
>not
> > directly suited for dynamic forms (the Dyna prefix is a bit misleading).
> > What you probably want are map-backed ActionForm beans (which can be
> > vanilla or Dyna, actually, with some caveats). There is no documentation
>in
> > the user guide for them, but I've written a patch that adds some.
>Comments
> > on it are greatly welcomed.
> >
> > - donald
> >
>
>
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? patch
Index: doc/userGuide/building_controller.xml
===================================================================
RCS file:
/home/cvspublic/jakarta-struts/doc/userGuide/building_controller.xml,v
retrieving revision 1.23
diff -u -r1.23 building_controller.xml
--- doc/userGuide/building_controller.xml 27 Jul 2002 21:53:13 -0000 1.23
+++ doc/userGuide/building_controller.xml 4 Sep 2002 15:36:28 -0000
@@ -7,6 +7,7 @@
<author>Ted Husted</author>
<author>Martin Cooper</author>
<author>Ed Burns</author>
+ <author>Donald Ball</author>
<title>The Struts User's Guide - Building Controller Components</title>
</properties>
@@ -90,11 +91,92 @@
</section>
<section name="4.2.1 DynaActionForm Classes"
href="dyna_action_form_classes">
- <p>[:TODO:]</p>
+ <p>Maintaining a separate concrete ActionForm class for each form in
your struts application is time-consuming. This can be alleviated through
the use of DynaActionForm classes. Instead of creating a new ActionForm
subclass and new get/set methods for each of your bean's properties, you can
list its properties, type, and defaults in the struts configuration
file.</p>
+ <p>For example, add the following to struts-config.xml for a UserForm
bean that stores a user's given and family names:</p>
+<pre>
+<![CDATA[
+<form-bean name="UserForm" type="org.apache.struts.action.DynaActionForm">
+ <form-property name="givenName" type="java.lang.String" initial="John"/>
+ <form-property name="familyName" type="java.lang.String"
initial="Smith"/>
+</form-bean>
+]]>
+</pre>
+ <p>The list of types supported by DynaActionForm beans includes:</p>
+ <ul>
+ <li>java.lang.BigDecimal</li>
+ <li>java.lang.BigInteger</li>
+ <li>boolean and java.lang.Boolean</li>
+ <li>byte and java.lang.Byte</li>
+ <li>char and java.lang.Character</li>
+ <li>java.lang.Class</li>
+ <li>double and java.lang.Double</li>
+ <li>float and java.lang.Float</li>
+ <li>int and java.lang.Integer</li>
+ <li>long and java.lang.Long</li>
+ <li>short and java.lang.Short</li>
+ <li>java.lang.String</li>
+ <li>java.sql.Date</li>
+ <li>java.sql.Time</li>
+ <li>java.sql.Timestamp</li>
+ </ul>
+ <p>If you do not supply an initial attribute, numbers will be
initialized to 0 and objects to null.</p>
</section>
- <section name="4.2.3 Map-backed ActionForms"
href="map_action_form_classes">
- <p>[:TODO:]</p>
+ <section name="4.2.2 Map-backed ActionForms"
href="map_action_form_classes">
+ <p>The DynaActionForm classes offer the ability to create ActionForm
beans at initialization time, based on a list of properties enumerated in
the struts configuration file. However, many HTML forms are generated
dynamically at request time. Since the properties of these forms' ActionForm
beans are not all known ahead of time, we need a new approach.</p>
+ <p>Struts allows you to make one or more of your ActionForm's
properties' values a Map instead of a traditional atomic object. You can
then store the data from your form's dynamic fields in that Map. Here is an
example of a map-backed ActionForm class:</p>
+<pre>
+<![CDATA[
+public FooForm extends ActionForm {
+
+ private final Map values = new HashMap();
+
+ public void setValue(String key, Object value) {
+ values.put(key, value);
+ }
+
+ public Object getValue(String key) {
+ return values.get(key);
+ }
+
+}
+]]>
+</pre>
+ <p>In its corresponding JSP page, you can access objects stored in
the values map using a special notation: <i>mapname(keyname)</i>. The
parentheses in the bean property name indicate that the bean property named
<i>mapname</i> is indexed using Strings (probably backed by a Map) and that
struts should look for get/set methods that take a String key parameter to
find the correct sub-property value. Struts will, of course, use the
<i>keyname</i> value from the parentheses when it calls the get/set
methods.</p>
+ <p>Here is a simple example:</p>
+<pre>
+<![CDATA[
+<html:text property="value(foo)"/>
+]]>
+</pre>
+ <p>This will call the getValue() method on FooForm with a key value
of "foo" to find the property value. To create a form with dynamic field
names, you could do the following:</p>
+<pre>
+<![CDATA[
+<% for (int i=0; i<10; i++) {
+ String name = "value(foo-" + i + ")";
+ <html:text property="<%=name%>"/><br/>
+%>
+]]>
+</pre>
+ <p>Note that there is nothing special about the name <i>value</i>.
Your map-backed property could instead be named <i>property</i>,
<i>thingy</i>, or any other bean property name you prefer. You can even have
multiple map-backed properties on the same bean.</p>
+ <p>In addition to map-backed properties, you can also create
list-backed properties. You do so by creating indexed get/set methods on
your bean:</p>
+<pre>
+<![CDATA[
+public FooForm extends ActionForm {
+
+ private final List values = new ArrayList();
+
+ public void setValue(int key, Object value) {
+ values.set(key, value);
+ }
+
+ public Object getValue(int key) {
+ return values.get(key);
+ }
+}
+]]>
+</pre>
+ <p>In your JSP pages, you access individual entries in a list-backed
property by using a different special notation: <i>listname[index]</i>. The
braces in the bean property name indicate that the bean property named
<i>listname</i> is indexed (probably backed by a List), and that struts
should look for get/set methods that take an index parameter in order to
find the correct sub-property value.</p>
</section>
<section name="4.3 Action Classes" href="action_classes">
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