I was wondering if in NHibernate it is possible to have it automatically validate the length of fields and have it throw an exception if it is too long.

I've set the type="string" and Length="xx" but it doesn't complain when the length is exceeded.

Thanks in advance

Have a look at NHibernate Validator project http://nhforge.org/wikis/validator10/nhibernate-validator-1-0-0.aspx