Thursday, May 1, 2008

Eclipse, Toplink, JPA and a Lost Evening

So I decided to put together a simple web-application using the dynamic web project in Eclipse. However, my recent workspace had become rather "corrupted" and so I had created a new one named "eclipse 3.3" (under my common \dev\workspace area). To my dismay, I simply could not get my web-application which was working in my old workspace to work. The crazy thing about this, is I know my persistence.xml and project was setup correct. The Tomcat log was producing the following:
INFO: The configured persistenceUnitName is: MileageTracker
[TopLink Config]: 2008.05.01 10:23:15.703--ServerSession(2165595)--Thread(Thread[main,5,main])--The alias name for the entity class [class org.javad.mileage.model.Vehicle] is being defaulted to: Vehicle.
javax.persistence.PersistenceException: No Persistence provider for EntityManager named MileageTracker: The following providers:
Returned null to createEntityManagerFactory.

at javax.persistence.Persistence.createEntityManagerFactory(
at javax.persistence.Persistence.createEntityManagerFactory(
Now what is curious about this, is Toplink was found, and it determined some information about my EntityBean. I spent a lot of time trying to discover what was wrong here, checking my other projects from the previous workspace etc. It turns out the problem was an Eclipse bug in which you have workspaces with spaces (" ") it will fail to find the Entity Manager Factory. The reference bug ID is 210280 Sufficit to say, this cost me a few hours of productivity.....

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