Customizing Grails/Groovy Drop-Down List

Grails is a powerful framework based on Groovy. Since most of the basic CRUD operations are done by Grails, we sometimes want to edit some of the fields generated in the GSP specially if it is a drop-down list.

There are two ways to edit the drop-down list:
1. By overriding the toString function of the domain

class Student {
          String firstName
          String lastName

          String toString(){
               StringBuilder sb = new StringBuilder()
               sb.append(firstName)
               sb.append(" ")
               sb.append(lastName)
               return sb.toString()
          }
     }

Without touching the GSPs, the drop-down list will show the first names and last names of the students and not the default package.domain : id (e.g. Student : 1)

2. By setting the attribute optionValue in g:select tag

optionValue="firstName"

will show only the first names of the students. If you want to show the first names and last names, you may opt to use

optionValue="${{it.firstName + ' ' + it.lastName}}"

Note that character/s can be inserted for each iteration inside single quotes.