Take a look at this before creating your Grails forms:
The Elevator Pitch
Currently to render fields that are aware of domain class constraints such as maximum field length, “inList” options in a select box etc, you have a fair bit of manual coding to do in your GSP pages.
You want tags that are constraint-aware, and also aware of the current values of fields, and able to display the errors of a field next to the field itself on the form. You also want to not have to do
That’s what this taglib does.