Validate field values on form

A nifty trick for comparing the "old" value against the "new" value using "obj.orig()" when validating a field on a form.

Example:

Change the behavior of the "Customer Group" on "CustTable" form.

Overwrite the method "validate" on the field "CustGroup" on the data source on "CustTable" form.

Original method: <xpp>

public boolean validate() {

   boolean ret;

   ret = super();

   return ret;

} </xpp>

Change method: <xpp> public boolean validate() {

   boolean ret;
   ;
   if(custTable.orig().CustGroup == '30') // Non changeable group.
   {
       info('You cannot change this Customer group');
       ret = false;
   } else {
       ret = super();
   }
   return ret;

} </xpp>

Note: I've explained the general principle for validating a field against it's old value, however there are some issues with the data source not refreshing data set when changing the value back and forth.