The ability to check data input by users is one of the features normally required by any data entry system.
A column cannot accept a value higher than 100 - if another column has not been defined as "Custom".
This validation logic has to be implemented in a Procedure associated to the column in the "Before Write" Event, which carries out these actions:
- It obtains the Diff table related to the current operation (see What appens when a User performs a Write?)
- It reads the Diff table with the ExecuteReader activity
- If the read table has zero records, the user is not writing anything new and it stops running
- Otherwise, the operation continues
- It verifies that the values higher than 100 are on fields having the 'Custom' flag set
- Otherwise, the activity ThrowException throws an exception with an ad-hoc message (e.g., a code error, say 'ERROR-CODE-0032') for the error manager. It notifies the violation and the procedure finishes with a write abort.
The error handler, when set up properly, will be aware of any exception with an 'ERROR-CODE-' message.
Once an intentional exception has been detected, the handler will extract the code and send the user a more user-friendly message.