Re: [eclipselink-users] (Newbie)Optimistic Locking for Web Apps

[RogerV <roger.varley@xxxxxxxxxxxxxx>]

tch wrote:
> 
> Just for future people, why don't you let us know what you missed?
> 

I'm using the Struts 2 framework which will "automagically" create a new
instance of the entity for me. I ommitted to include the version number as a
hidden field on the form to return to the framework, so Struts 2 just gave
it the default value which is insufficient to trigger the optimistic
locking. Once I added the version attribute to the html form, optimistic
locking works like a charm - it's actually embarassingly easy to implement!

So in summary;

1) Add the version number field to your database table.
2) Add the version annotation to your entity.java
3) Include the version number as a hidden field in your html data entry form
and return it with the update request.
4) Create a new Entity instance with the returned data (this is the bit that
Struts does for you)
5) EntityManager.merge(entity)

Regards

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