Saturday, February 21, 2009

Workaround for LOV on Primary Key Attribute

There is a problem with LOV component, when it is defined on Primary Key attribute - registered Bug #8275169. Until problem will be fixed, workaround can be as following - to define second dummy transient attribute for Primary Key attribute and use it on the page. However, during commit - in doDML method on Entity to substitute real attribute value with value from transient attribute.

For example, Entity with Primary Key attribute DepartmentId:


I have defined LOV for this attribute in VO and on runtime trying to use LOV:


However unsuccessfully, error is generated:


You can download sample application - LOVPrimaryKey.zip, where described workaround is implemented.

To give you more light about workaround, I will explain it in detail.

First, Primary Key attributes always are with Mandatory validation rule, however I removed this rule from DepartmentID and declared it for my transient attribute DepartmentId_Dummy. It is done in order to remove unnecessary check, since we are creating mirror attribute:


In getter method for transient attribute I need to return real attribute value during first load in order to display not blank values but correct ones:


In overridden doDML method value from transient attribute is copied back to real attribute:


DepartmentId attribute Display Hint is set to Hide - this means will not be visible in ViewController:


Transient attribute will be visible with user friendly label:


When developer will drag and drop Data Control on the page, wizard will not list original DepartmentId attribute, because it was set as Hide:


Now LOV will work, however I strongly believe this bug will be fixed in next build and there will be no need to apply this workaround !

Spanish Summary:

Este artículo se describe un Tip para solucionar un bug que se produce cuando se utiliza una Lista de Valores (LOV) para recuperar un dato en un formulario.

2 comments:

natarts said...

My LOV doesn't work. I used ViewObject, not ViewObjectLOV.
When I click row in LOV, error is occured.
Error text is:
oracle.adfinternal.view.faces.config.rich.RegistrationConfigurator handleError
SEVERE: Server Exception during PPR, #1
javax.servlet.ServletException

natarts said...

Hello!
I want to install Jdev Release 1 Patch Set 1 (11.1.1.2.0).
Is this bug fixed in this release?
Thanks