Validation based on view attributes

Question

JDeveloper 11.1.1.x
What is the best practice to create validations based on a view attribute from a view object that is of a level higher in the hierarchy?
For example:
     * Use the departments and employees tables from the hr schema.
     * Create an EO for only the employees table, so not for the department table
     * Create VO's for both tables. You should create the Viewlink manually between both views.
     * In the query for the department, add a calculated field in the query.
     For example : availableSalary : 100000 - (select sum(salary) from employees where department_id = Departments.DEPARTMENT_ID) availableSalary
     * I would like to add a validation on the salary field of the employee EO, that says that the new value shouldn't be bigger then the availableSalary field
     Be aware : that when changing an existing salary, only the difference between the old and new salary should be taken into account
     (This removes the "Compare with View Object Attribute" possibility :-()
     * I also want to use some fields from the departments view in my error message on the salary field of the employees EO.
How can we best tackle these requirements ?
Thank you in advance.
Filip Huysmans.

Answer 1

Filip,
I think you are trying to avoid the lesser cost of a Department Entity by an extremely expensive way to get to the comparison done. Firstly, you wire a view instance with an entity, which is strange as there is no association between the entity and the View Object. So all you would have is to access a method in the AM Impl method that looks up the VO and returns the current row's information you need. This AM method can be referenced from the entity object using groovy to perform the comparison (you see that even this is kind of awkward as it connects the entity to the AM, producing a tight coupling that makes any of your code reviewers shake heads in disbelieve). Assuming the update of the VO updates the entity (Departments EO you don't have), you could follow an association using Groovy to perform the validation (which I think sounds easier to do (though by the small cost of creating an EO)
Btw.:
if you have a ViewLink defined then the transient attribute can be easier calculated using Groovy
10000 - DetailTargeName.sum('Salary');
I would think its less expensive then running a SQL query for each department Id
Frank