nested iterate with ArrayList

[MK Lee]

I'm not familiar with Struts, please forgive me if I'm asking stupid question.

My struts-config:

<form-bean name="orderForm" type="org.apache.struts.action.DynaActionForm">
<form-property name="action" type="java.lang.String"/>
<form-property name="step" type="java.lang.String"/>
<form-property name="value" type="java.util.HashMap"/>
<form-property name="orderDetails" type="java.util.ArrayList"/>
</form-bean>

My jsp:

<nested:iterate property="orderDetails">
<nested:text property="itemId"/>
<nested:text property="qty"/>
</nested:iterate>

the jsp can successfully generate the corresponding page with correct data in the html:

<input type="text" name="orderDetails[0].itemId" value="5704822833">
<input type="text" name="orderDetails[0].qty" value="1">
<input type="text" name="orderDetails[1].itemId" value="5704832539">
<input type="text" name="orderDetails[1].qty" value="1">
<input type="text" name="orderDetails[2].itemId" value="5704843607">
<input type="text" name="orderDetails[2].qty" value="1">

However, when I try to submit this page to the action class, before reaching the action class, it generates:

javax.servlet.ServletException: BeanUtils.populate
at org.apache.struts.util.RequestUtils.populate(RequestUtils.java:1254)
at org.apache.struts.action.RequestProcessor.processPopulate(RequestProcessor.java:821)
...
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.RangeCheck(ArrayList.java:507)
at java.util.ArrayList.get(ArrayList.java:324)
at org.apache.struts.action.DynaActionForm.get(DynaActionForm.java:298)
at org.apache.commons.beanutils.PropertyUtils.getIndexedProperty(PropertyUtils.java:474)
at org.apache.commons.beanutils.PropertyUtils.getIndexedProperty(PropertyUtils.java:428)
at org.apache.commons.beanutils.PropertyUtils.getNestedProperty(PropertyUtils.java:770)
at org.apache.commons.beanutils.PropertyUtils.getProperty(PropertyUtils.java:801)
at org.apache.commons.beanutils.BeanUtils.setProperty(BeanUtils.java:881)
at org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:808)
...

Why is that? How can I solve it?

[Marc Peabody]

You'll either have to change some code (most DynaUsers prefer not to) or put the form in session scope.

What is happening:
1) I assume their is an Action to populate the ActionForm with orderDetails before going to the jsp because you show that it prepopulates correctly.
2) When you submit the jsp, orderDetails[0].itemId is calling:
getOrderDetails("0").setItemId() but fails because the orderDetails' values are not in the ActionForm (a new ActionForm is created for the submission because it is declared as request scope and, well, this is a different request from the user).
3) At this point it looks for the index of 0 in the orderDetails ArrayList but finds that the list is empty (size=0) and throws and IndexException

If you're not afraid of getting your hands dirty you can come up with a way to put the ArrayList back into the new ActionForm. The reset() method might be a good place to do this.

[MK Lee]

hahaa...
i used the simplest trick: modify the form scope to session
and it works fine
Thx a lot
^3^