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From: Eric Lentz <ericlentz@outfastsource.com>
Date: Mon, 3 Dec 2012 12:05:03 -0500
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Subject: Re: Extending base class and accessing implementation's fields in
 Struts 2
To: Struts Users Mailing List <user@struts.apache.org>
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I'm almost there. I didn't suspect that it would work that way with the
iterator. Should have tried it first! Thanks Dave.

On the way back, such as in a post, if BaseObject is an interface or
abstract, as I'm hoping for it to be, then Struts tries to instantiate the
BaseObject type, which it can't, so it throws:

[com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler] Could
not create and/or set value back on to object
java.lang.InstantiationException
at
sun.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(InstantiationExceptionConstructorAccessorImpl.java:30)
 at java.lang.reflect.Constructor.newInstance(Constructor.java:501)
at java.lang.Class.newInstance0(Class.java:350)
 at java.lang.Class.newInstance(Class.java:303)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:130)
 at
com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler.createObject(InstantiatingNullHandler.java:159)
at
com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler.nullPropertyValue(InstantiatingNullHandler.java:137)
 at
com.opensymphony.xwork2.ognl.OgnlNullHandlerWrapper.nullPropertyValue(OgnlNullHandlerWrapper.java:21)
at ognl.ASTProperty.getValueBody(ASTProperty.java:118)
...etc.

Any ideas on solving that?

- Eric

On Mon, Dec 3, 2012 at 11:19 AM, Eric Lentz <ericlentz@outfastsource.com>wrote:

> I have
> List<BaseObject> foo
>
> The list is of type BaseObjectImpl
>
> BaseObject has fields:
> String a
> String b
>
> BaseObjectImpl has fields:
> String c
> String d
>
> Now I'm in a JSP and want to iterate foo (using <s:iterator>), accessing
> fields c and d (inside iterator using <s:property>, for example). How? As
> far as Struts knows I'm dealing with BaseObject. Is there a way for me to
> cast to BaseObjectImpl without creating a StrutsTypeConverter for every
> object I'm extending? In my use case, there will be several and the
> temptation is to just define the list with the implementation which foils
> reusability patterns (e.g., List<BaseObjectImpl>).
>
> Likewise, what to do when posting back to a field like this:
> BaseObject bar  (which has BaseObjectImpl as its implementation) e.g.,
> <s:textfield name="bar.c" />
>
>
> Is there a totally different approach that would be better or is
> StrutsTypeConverter the only good answer?
>
> - Eric
>
>

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