class ArticlesController < ApplicationController

  def index
    @articles = Article.all
  end

  def new
    @article = Article.new
  end

  def create
    @article = Article.new(article_params)
    if @article.save
      flash[:success] = "Article has been created"
      redirect_to articles_path
    else
      flash.now[:danger] = "Article has not been created"
      render :new
    end
  end

  def show
    @article = Article.find(params[:id])
  end

  def edit
    @article = Article.find(params[:id])
  end

  def update
    @article = Article.find(params[:id])
    if @article.update(article_params)
      flash[:success] = "Article has been updated"
      redirect_to @article
    else
      flash.now[:danger] = "Article has not been updated"
      render :edit
    end
  end

  def destroy
    @article = Article.find(params[:id])
    if @article.destroy
      flash[:success] = "Article has been deleted"
      redirect_to articles_path
    end
  end

  protected

  def resource_not_found
    message = "The article you are looking for could not be found"
    flash[:alert] = message
    redirect_to root_path
  end

  private

    def article_params
      params.require(:article).permit(:title, :body)
    end

end

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

  def index
    @articles = Article.all
  end

  def new
    @article = Article.new
  end

  def create
    @article = Article.new(article_params)
    if @article.save
      flash[:success] = "Article has been created"
      redirect_to articles_path
    else
      flash.now[:danger] = "Article has not been created"
      render :new
    end
  end

  def show
  end

  def edit
  end

  def update
    if @article.update(article_params)
      flash[:success] = "Article has been updated"
      redirect_to @article
    else
      flash.now[:danger] = "Article has not been updated"
      render :edit
    end
  end

  def destroy
    if @article.destroy
      flash[:success] = "Article has been deleted"
      redirect_to articles_path
    end
  end

  protected

  def resource_not_found
    message = "The article you are looking for could not be found"
    flash[:alert] = message
    redirect_to root_path
  end

  private

    def article_params
      params.require(:article).permit(:title, :body)
    end

    def set_article
      @article = Article.find(params[:id])
    end

end

Add before filter to articles controller
Add before filter to articles controller
