Web框架中的控制器？ [红宝石，Grails等。]它们如何工作？

Question

So the thing that I want to do is direct the login page to the admin page(eg: "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"] 
}