Re: [hibernate-dev] [ORM/OGM] String-typed version properties

Thoughts, anyone? Steve? Thanks, --Gunnar 2013/11/21 Gunnar Morling <gunnar(a)hibernate.org&gt; > All, > > I'm working on supporting on the CouchDB backend for OGM, and more > specifically on integrating the optimistic locking functionality which is > built into CouchDB [1]. > > For that purpose, each CouchDB document has a defined field "_rev" which > is a UUID and is updated on the server-side upon each write. So I thought I > could map this attribute like this: > > @Generated //this prop. needs to be read back value after writes > @Version //this prop. is used for optimistic locking > String _rev; > > But this gave me a CCE since @Version is not allowed on Strings > (org.hibernate.type.StringType is no VersionType). > > Looking around, I found BinaryType which looks like what'd I need for > Strings, there is also a note mentioning basically the same use case case > [2]. If I register a custom type derived from StringType with an equivalent > implementation of the VersionType contract, I get the behavior I need. > > Does anyone see a problem with making o.h.t.String a VersionType in this > way (i.e. it'd only support DB-generated values)? > > Thanks, > > --Gunnar > > [1] https://hibernate.atlassian.net/browse/OGM-392 > [2] "only known application of binary types for versioning is for use > with the TIMESTAMP datatype supported by Sybase and SQL Server, which are > completely db-generated values" > >