What is DynaActionForm and how to use it ?

A specialized subclass of ActionForm that allows the creation of form beans with dynamic sets of properties (configured in configuration file), without requiring the developer to create a Java class for each type of form bean.

Using a DynaActionForm instead of a custom subclass of ActionForm is relatively straightforward.

You need to make changes in two places :

In struts-config.xml

Change your to be an org.apache.struts.action.DynaActionForm instead of some subclass of ActionForm

<form-bean name="loginForm" type="org.apache.struts.action.DynaActionForm" >

    <form-property name="userName" type="java.lang.String" />

    <form-property name="password" type="java.lang.String" />

</form-bean>

In your Action subclass that uses your form bean

• Import org.apache.struts.action.DynaActionForm
• Downcast the ActionForm parameter in execute() to a DynaActionForm
• Access the form fields with get("field") rather than getField()

Example

import org.apache.struts.action.DynaActionForm;

public class DynaActionFormExample extends Action {

public ActionForward execute(ActionMapping mapping, ActionForm form, 

    HttpServletRequest request, HttpServletResponse response) 

    throws Exception {       

      DynaActionForm loginForm = (DynaActionForm) form;

      ActionMessages errors = new ActionMessages();       

        

      if (((String) loginForm.get("userName")).equals("")) {

         errors.add("userName", 

                    new ActionMessage("error.userName.required"));

      }

      if (((String) loginForm.get("password")).equals("")) {

         errors.add("password", 

                    new ActionMessage("error.password.required"));

        }

        // other processing here

}