Conditional validation - When field changed

Question

APEX 4.2.1
Simple wizard-generated DML form on a table. Hidden numeric primary key (PK), displayed multi-column unique key (UK1,UK2); standard table design.
Combination of conditional readonly and editable page items. NOT EXISTS validation to replace ORA-0001 with a friendlier error message. Validation should fire only when key fields (UK1 or UK2) are changed. Changes to other fields on the record should be allowed.
But APEX server side conditions don't track item level changes. For instance, we can't say "Fire this validation only when P1_X or P1_Y are changed"
How would this sort of thing be done? By adding OnChange dynamic actions on all the page items of interest to set a hidden page item, save that to session state and refer to it in the validation's Condition?
Is this the right way to approach this?
Thanks

Answer 1

VANJ wrote:
APEX 4.2.1
Simple wizard-generated DML form on a table. Hidden numeric primary key (PK), displayed multi-column unique key (UK1,UK2); standard table design.
Combination of conditional readonly and editable page items. NOT EXISTS validation to replace ORA-0001 with a friendlier error message. Validation should fire only when key fields (UK1 or UK2) are changed. Changes to other fields on the record should be allowed.
But APEX server side conditions don't track item level changes. For instance, we can't say "Fire this validation only when P1_X or P1_Y are changed"
How would this sort of thing be done? By adding OnChange dynamic actions on all the page items of interest to set a hidden page item, save that to session state and refer to it in the validation's Condition?
Is this the right way to approach this?Not in 4.2 in my opinion. Drop the validation, let the DML process raise the ORA-00001 exception, and use the new error handling features to provide a user-friendly message.