Entity Attribute Validation via XML

Question

We have an Entity object with 2 attributes. I'm trying to setup a new validation rule for attribute B that forces it to be GREATER THAN attribute A. It seems that the only way to accomplish this is by using a MethodValidator. The most obvious choice, however, would by the CompareValidator where "AttributeB" is "GreaterThan" "AttributeA", but that isn't an option. I can only setup a comparison to a "Literal Value", a "Query Result", or "View Object Attribute". The "View Object Attribute" won't work because it will compare it to the value of the first row of the view. I'm in the Entity, so I can't gaurantee that the same row's value would always be compared using this method. It seems to me that 9 times out of 10 you would want to compare 2 attributes from the same Entity row.
Am I missing something?
Erik

Answer 1

If you use a DB the natural thing to do is to define a DB constraint (in your case a unique index). This will be recognized by the framework and the constraint should be seen in the EO.
The other part is that you can't be sure if an attribute is unique as long as you do not commit (or at least post) it. only then the validation can check. I don't know if you can check not commited data from other users.
Timo