 To Define a Hidden Form Field
To Define a Hidden Form FieldSelect Hidden from the Display Class menu.
Click OK.
The Hidden display class corresponds to the <input type=hidden’/> HTML component. This component supports only single-valued data types because there is no way to reliably serialize and deserialize multi-valued data types.
If you have a List that you want to render it as a string, you must explicitly convert it to a String, as shown in the following example:
| <Field name=’testHiddenFieldList’ >
   <Display class=’Hidden’/ >
   <Derivation>
     <invoke name=’toString’>
       <List>
         <String>aaaa</String> <String>bbbb</String>
       </List>
     </invoke>
   </Derivation>
</Field> |