Also posted to Struts 2 forum on Nabble - apologies if this causes a duplicate posting.
Planning to use Struts 2 and JPA (OpenJPA) in a new application development and am spending some time to review options of how it should be done. There will be a large CRUD component within the application so I am working on the patterns to use in those scenarios. Following the CRUD examples in the Struts 2 In Action (and other sources), I have been experimenting with the ParamsPrepareParams stack. Using the pattern shown in the Struts 2 in Action book, the following is my understanding of the relevant points in the execution path. - when an "edit" (save) action is called the prepare() method retrieves the model object from the database (because there is an ID in the HTTP Request parameters). - the Params interceptor is invoked then loads the values from the HTTP Request parameters. None of the documentation describes why this is done, I assume the reason is to ensure that the Model object is fully populated (not all of the attributes may be on the UI and thus in the HTTP Request parameters). - the action is then invoked - and persists the updated Model object (delegated to a service) >From what I can see, this causes a conflicts with the use of a version attribute for Optimistic Locking on the database. When the updates from the HTTP Request parameters are merged in with a newly retrieved model object the version number/timestamp is the value retrieved from the database. Even if that row had been updated by another user/thread since being retrieved the first time, the version checking would not catch the conflicting updates becuase it has been refreshed to the latest value in the DB. It seems a fairly fundamental and obvious problem so I am worried that I am mis-understanding the pattern described in the book (and repeated in other samples). I know that the examples in the book are simplified, but I would expect something like this to be commented on in the text. Am I missing something ??? Can anybody confirm or contradict my reasoning? -- View this message in context: http://www.nabble.com/Struts-2-Prepare-Interceptor%2C-CRUD-Pattern-and-Optimistic-Locking-tp19612252p19612252.html Sent from the Struts - User mailing list archive at Nabble.com. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
