controllers in web frameworks ? [ruby, Grails, etc..] How do they work? - ruby

Question

So the thing that I want to do is direct the login page to the admin page(e.g: "admin.gsp") if username "admin" is entered and password "pass" is entered. or direct it to the user page if username "user" and password "pass" is entered
However I do not understand how exactly controller works.
So when you redirect the page to a specific controller and specific method, how do you make it redirect it to a specific page. What code do you implement inside that method ?
to explain my question better. Below we have the code for controller User, with an if else statement depending on what the user typed in the login boxes.
package file_download
class UserController {
def index() {
//code that directs the page to username page, let's call it or user.gsp
}
def login = {
if(params.username == "admin" && params.password == "pass")
{
session.user = "admin"
redirect(controller:"admin",action:"admin")
}
else if(params.username == "user" && params.password == "pass")
{
session.user="user"
redirect(controller:"user",action:"index")
}
else
{
flash.message = "login failed"
}
redirect(controller:"user",action:"login")
}
def logout = {
session.user = null
redirect(action: 'index')
}
}
now here, we have the admin controller, with the action index, that should have a code implemented to direct the page to... admin.gsp, or admin.html, watever the admin page is called
package file_download
class AdminController {
def index() {
//code that takes us to admin page let's call it admin.gsp
}
}
How do we exactly do that ?
I need a little bit of an explanation on controllers.
Thank you. Please ask if you need more clarification on the question as I will edit it.

Answer 1

I think you are having wrong assumptions. In Grails (I don't know rails) when you go to the login page, let's say
/app/user/login
then, at FIRST the controller method is being called (def login()), so your logic shouldn't go there, it should actually do nothing and by convention it will end up rendering login.gsp. Next, your user fills in his username/pass and submits form, there goes the second request let's say to
/app/user/auhtenticate
and here's where your logic should go and the redirects will work as you expect
So basically - controller method is called first and (unless you specify gsp to be rendered or do a redirect) after the method is executed, the gsp view is being rendered

Answer 2

I know nothing of rails, however in grails what you are looking for is render.
Render:( http://grails.github.io/grails-doc/latest/ref/Controllers/render.html )
so the code would look something like this
def index() {
render view: "/directory/inside/views/admin" model: [thing1: "Thing One"]
}