You could create a mixin which uses @BindParameter to set the "validate" parameter on the Field.
You could then create a ComponentClassTransformWorker2 which attaches the mixin to TextField and TextArea by default. See the blog post here for a similar pattern: http://tawus.wordpress.com/2011/08/01/tapestry-mixins-classtransformations/ I'm hoping you won't hit a variation of this issue: https://issues.apache.org/jira/browse/TAP5-2099
