nested struts2 validation

[Stephen Ince]

Hi,
  I would like to do nested struts2 validation. I have two questions.

1) How do I specify the validation for the following field. Can some point me 
to some documenation for the expression validation.


<input type="text" name="searchResults[${i}].resource.name" ..
validation.xml

<validator type="expression">
<param name="expression">
searchResults.{#this.resource.name.length() &gt; 0}.{? #this == false }.size() 
&lt;= 0
</param>
<message key="resource.name.required" />
</validator>

2) Can specify a particular method for an action class.

e.g.

SearchAction-search!update-validation.xml
where
search -- is the action alias and
update -- is the method to execute in SearchAction

Steve