gistfile1.rb

class ArticlesController < ApplicationController
  before_action :set_article, only: [:show, :edit, :update, :destroy]

  def index
    @articles = Article.all
    @articles_category = Article.order(:category)
    @users = User.all
  end

  def show
    # @article is available here because we are running the private
    # set_article method in the before action (actually defined below). This can feel a little magical,
    # but try setting up @article without the before action to see what's going on.
    
    # Remember that any instance variables we set here are accessible in the view
    # and we can basically add any code here:
    @cat_sound = "Meow" # You can now do <%= @cat_sound %> in the articles/show.html.erb view to print out "Meow" on the page.
    
    # Imagine we had articles on comments
    # @comments = Comment.where(:article_id => @article.id)
    # Or, even better:
    # @comments = @article.comments
    
    # We also have access to this mystical params hash:
    @article_id_we_care_about = params[:id]
    # Check out the rails server console output when you visit an article page to see where this is coming from.
    
    # The params hash comes from the parts of the url that scope a route or give you additional variables to use in the controller. 
    # If you run rake routes in your project, you will see that there is probably a route that looks like this:
    # GET /articles/:id
    # Check out that last :id part. Look familiar?
  end
  
  private
  
    def set_article
      @article = Article.find(params[:id])
    end