A.2. Persistent Enumerated Types

Hibernate provides a mechanism to help map the common Java type-safe enumeration pattern to a database column. Unfortunately, the approach taken requires your enumerations to have an integer representation to store in the database, forcing them back to the lowest common denominator semantics of the enumtype in the C language. I hope that a richer, string-based storage mechanism will eventually be supported, to dovetail nicely with the built-in support for this idiom that is coming in Tiger (JavaVersion 1.5). Storing enumerations as strings would also make them more readable to users of the raw database, a form of self-documenting storage.

To work with the current Hibernate implementation, your enumeration classes need only implement the net.sf.hibernate.PersistentEnum interface, and its fromInt() and toInt() methods. This is demonstratedin Chapter 6.