OGNL exceptions setting Struts2 checkbox value

Question

After adding a s:checkbox to my form, I get OGNL errors in the ParamsInterceptor:

WARN  [OgnlValueStack] Error setting expression '__checkbox_filter.findRejected' with value '[Ljava.lang.String;@dc926f'
ognl.OgnlException: target is null for setProperty(null, "findRejected", [Ljava.lang.String;@dc926f)

I am aware that the extra hidden field with underscores in its name (__checkbox_filter.findRejected) was correctly added by Struts2.

I don't understand, however, why the ParametersInterceptor is trying to set this property, that was added by Struts2, on my Action (which obviously doesn't contain a '__checkbox_filter' property).

It is normal to see this OGNL error coming from with Struts2 checkboxes? How can I avoid it?

Answer 1

I've just stumble across the very same problem.

You need to place the Checkbox Interceptor BEFORE the Parameters Interceptor in your interceptor stack.

This is the case by default, so I guess that you're using a custom stack...