I want to accomplish dynamic property defs by specifying properties in a
DynaActionForm from a database value. Not only define values for the
attributes but also define the attributes themselves. Is this possible?
I define a property in EditProductsAction by using
DynaActionForm dynaFrom = new DynaActionForm();
dynaFrom.set(propertyNameFromDB, new Integer(55));
and in the JSP i try to refer to this as:
<html:text property="<%= propertyNameFromDB>" />
I get the NullPointerException whose stack trace is given below. It is
occuring inside DynaActionForm.java on the call to getDynaClass()
protected DynaProperty getDynaProperty(String name) {
DynaProperty descriptor = getDynaClass().getDynaProperty(name);
/* Here */
............
}
Can anyone help me on what I am doing wrong?
Also what is the difference in the "key" and "name" of the form property?
Which method should I use in this case?
Thanks a lot.
Exception Stack Trace:
----- Root Cause -----
java.lang.NullPointerException
at
org.apache.struts.action.DynaActionForm.getDynaProperty(DynaActionForm.java:
551)
at
org.apache.struts.action.DynaActionForm.set(DynaActionForm.java:365)
at
com.etilize.cms.web.actions.EditProductSpecsAction.execute(Unknown Source)
at
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProces
sor.java:446)
at
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:266)
at
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1292)
at
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:510)
> You can auto-initialize primitives (and things like that) by using the
> "initial" attribute on the <form-property> element. But initializing a
> property that is an object requires an *instance* of that object to be
> available. It's not appropriate for a general purpose framework to just
> go and try to create such things, and hope that it's OK.
>
> A couple of strategies to consider:
>
> * Create the form bean in a separate Action that can pre-initialize
> all of the necessary properties for you. This will often be the
> best course of action when you are creating edit forms for modifying
> existing database data.
>
> * Create a custom subclass of DynaActionForm with a reset() method
> that, among other things, instantiates your credit card object
> and stores it:
>
> put("creditCard", new my.package.CreditCard()");
>
> Struts calls the reset() method for you when *it* creates the form
> bean instance. If you create one yourself, you'll need to remember
> to call this method.
>
>
> Craig
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