Grails form field always null - forms

Question

I want to add password confirmation to my project's registration page. But I'm having a problem with value of one of my fields. All the fields are ok but the password2 field, it's the confirmation password and is a transient field of User domain class. Here are my Domain, Controller and View codes
Domain class:
class User {
String fullName
String username
String email
String password
String password2
static transients = ['password2']
static constraints = {
username size: 5..15, blank: false, unique: true
email email: true, blank: false
password blank:false, size:5..15, matches:/[\S]+/, validator:{ val, obj ->
if (obj.password != obj.password2)
return 'user.password.dontmatch'
}
}
}
Part of the Controller:
if (request.method == 'POST') {
// create domain object and assign parameters using data binding
def u = new User(params)
if (! u.save()) {
// validation failed, render registration page again
flash.error = "error(s) creating user: Value of the confirmation password is: "+u.password2
//render(view:"/signup",model:[user:user])
return [user:u]
} else {
// validate/save ok, store user in session, redirect to homepage
session.user = u
redirect(controller:'home')
return
}
} else if (session.user) {
// don't allow registration while user is logged in
redirect(controller:'home')
return
}
And a part from the View:
<div><input class="pretty-input ${hasErrors(bean:user,field:'email','input-error')}" type="email" name="email" value="${user?.email}" ></input><span>— Enter email</span></div>
<div><input class="pretty-input ${hasErrors(bean:user,field:'password','input-error')}" type="password" name="password"></input><span>— Choose a password</span></div>
<div><input class="pretty-input ${hasErrors(bean:user,field:'password2','input-error')}" type="password" name="password2"></input><span>— Repeat the password</span></div>
My code works if I remove password's custom validation because password2's value is always null. I why this happens when all other fields works but password2 not.

Answer 1

Trasients fields are not bindables by default, thus you cannot pass params to fill it.
You can do this:
static constraints = {
... your code here
password2 bindable: true
}
But I recommend you to use a command object to validate that condition, it is clever.