Rails Routing Basics

Posted for memorandum.

environment

ruby 2.7.1 Rails 6.0.3.2

It is a prerequisite that Rails has been installed.

Create the required files with the generate command

bundle exec rails g controller <controller_name> <method_name>

↓

bundle exec rails g controller home index

The necessary files are created. If you want to delete it, delete command

 bundle exec rails d controller home index

routes.rb

bundle exec rails routes

or

bundle exec rails routes | grep xxx
(Narrow down)

You can see the routing settings in the directory.

Points to see

 URI Pattern                        Controller#Action
  /articles/index(.:format)         articles#index

You can jump to the Action index of Controller articles by accessing / articles / index. You can see it by starting the server with rails s and accessing localhost :: 3000. As a Rails rule, the Controller name has a hierarchical structure on the View side as it is.

Example: HomeController (controller name) View directory → home (directory name) /index.html.erb (file name)

How to pass values from Controller to View

Use instance variables

class HomesController < ApplicationController
  def index
    #Instance variables
    @message = "message"
  end
end

You can call the value anywhere in the Controller by prepending @ to the variable. You can also pass the value of a variable to View. In this example, the string "message" contained in the instance variable @message is passed.

<h1>Homes#index</h1>
<%= @message %>

If you want to call Ruby in HTML, you can use <%%>. If you want to output something, add <% =%> and it will be output. Since we are passing the instance variable @message, the string "message" is displayed in HTML.