Are there any statements in JPA spec or official docs about certain JPA implementations which describe the behavior when we annotate entity's methods and when we annotate entity's fields?
Just a few hours ago I met an ugly problem: I use JPA (via Hibernate, but without anything Hybernate-specific in java code) with MS SQL Server. And I put all annotations on entities' fields (I preferred this style until this day).
When I looked at the DB I found that all table columns which should be foreing keys and which should contain some integers (ids) in fact had varbinary(255, null) type and contained hashes of something (I don't know what was that but it looked as a typical MD5 hash).
The most frustrated thing is that the app worked correctly. But occasionally (on updates) I got MS SQL exception which stated that I tried to insert too long values and data cannot be truncated.
Eventually (as an experiment) I removed all annotations from entities fields and put all of them on methods. I recreated DB and all tables contained perfect FK column. And those columns stored integers (ids, like 1, 3 ,4 ...).
So, can somebody explain what was that?
I've found this SO thread and it's accepted answer says that the preferred way is to put annotations on fields. At least for my concrete case I can say that it's not true.