Java(TM) Boutique - Advanced Forms Handling in Struts 1.1

Tutorials : Advanced Forms Handling in Struts 1.1 :

To begin with, you'll notice that where Struts uses the attribute name "property", HTML uses "name". This is a bit confusing since Struts also has an attribute called "name", which is used to give the name of the bean whose "property" maps the control. The default for the "name" attribute is the name of the form's corresponding bean, so normally you don't need to use the "name" attribute.

Mapping and accessing the controls

Rule # 1:

The name of every control (given by the "property" attribute) must be defined in the form's bean, which may be:

1. a Java ActionForm bean defined in the form-beans section of the struts-config file, for example:

<form-bean name="detailForm"
   type="hansen.playground.DetailForm"/>

2. a "dynamic" form bean, also defined in the form-beans section of struts-config, for example:

<form-bean
   name="simpleForm"
   type="org.apache.struts.action.DynaActionForm">
     <form-property name="firstname" type="java.lang.String"/>
     <form-property name="site" type="java.lang.String[]"/>
</form-bean>

Note that a control may be mapped to an array if it contains more than one value.

Rule #2:

You may get or set the data in the controls from the execute method in the Action class:

1. ActionForm bean:

public ActionForward execute(ActionMapping mapping,
  ActionForm form,
  HttpServletRequest request,
  HttpServletResponse response) {

  DetailForm df = (DetailForm)form;
  String index  = df.getFirstName();
  String[] site = df.getSite();
  . . .
  df.setFirstName("John");
  . . .

You may of course also get or set the data in the ActionForm itself - for example in the validate method.

2. Dynamic form bean:

public ActionForward execute(ActionMapping mapping,
  ActionForm form,
  HttpServletRequest request,
  HttpServletResponse response) {
  DynaActionForm f = (DynaActionForm)form;

  String firstName = (String)f.get("firstname");
  String[] site    = (String[])f.get("site");
  . . .
  f.set("firstname", "John");
  . . .

The "interesting" controls

We'll not spend time on the simple controls "Text field", "Text area field"" and "Checkbox" (marked 1, 2, and 3 in the tables above) since they're all "single-valued", and therefore simple to handle in your classes. Instead we'll look further at the controls that have a set of options or values attached.

Set of fixed options

Let's first take care of the simple situation where the possible options of these controls are fixed. By "fixed" I mean that they won't change over time, for example "Male/Female" or "Spring/Summer/Autumn/Winter". The jsp-code example for such a control could be:

<html:radio property="sex" value="M"/>Male<br>
<html:radio property="sex" value="F"/>Female

Another example with a multi selection list:

<html:select property="food" multiple="true">
<html:option value="milk">Milk</html:option>
<html:option value="apple">Apple</html:option>
<html:option value="bread">Bread</html:option>
</html:select>

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