How to implement i18n message in controller

    In a Grails applicaton,actually it use spring message bundle for its i18n.let me give an example:

I have a Usercontroller and I want to display a message to our user when his user name or password is incorrectly and I want to show different language depend on the user's location.here is the code:

           if(user){

     session.userId=user.userId

     def redirectParams=session.originalRequestParams?session.originalRequestParams:[controler:'race']

     redirect(redirectParams)

     }else{    

                            //for now,it's a hard-code pattern.

     flash['message']='Please enter a valid user id and password'

     }

following we should do is add something in my message.propertis file.

in the file:grails-app/i18n/messages.properties we added English message

user.invilate.message=Please enter a valid user id and password

in the file:grails-app/i18n/messages_de.properties we added German message

user.invilate.message=Bitte geben Sie eine gültige Benutzer-ID und Passwort

then we change above code

flash['message']='${message(code:'user.invilate.message')}'