Controller Extension vs. AM Extension : Important

Question

Hi All,
Keeping in view OAF seeded Page Customization Best Practice which is more advisable in the following scenario:
(@Oracle Dev/Support guys: Please do provide arguments for/against. It would be helpful if u can point to any supporting Oracle Doc/metalink note )
Requirement: Include User Input Validation Logic in a seeded page (validate values of custom DFF entered against an existing segment combination in a custom table)
Solution Method1: Extending the region controller COSteps:
1. Capture User Input
2. Get current AM transactional object using
...//am is OAAplicationModule object
OADBTransacton txn= am.getOADBTransaction();
3. Use PreparedStatement to query the custom table
4. Include data validation logic
5. Point the region's controller to custom extended CO
Solution Method2: Create a nw ViewObject and Extend the region AM to include validation logicSteps:
1. Create VO for custom table
2. Extend AM and include validation logic
(The steps are just indicative and any other suggestions for solution is most appreciated. Also there is no need for any extra column/data to be shown or captured hence VO extension can b ruled out.)
thanks
--debashis                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

Answer 1

Since your AM is not root AM, you can go ahead with AM extension.
Only the extension of Root AM is not supported by OAF because of following issue
OA Framework does not support substituting a root application module due to
a known limitation in MDS and personalizations.
A root application module substitution has no runtime effect in a deployed environment outside JDeveloper or
could lead to a runtime error with a "Cannot Display Page" message in a LOV modal window in JDeveloper--Prasanna