discite/app/controllers/courses_controller.rb

class CoursesController < ApplicationController
  before_action :set_course, only: [:show, :edit, :update, :destroy]
  before_action :authenticate_user!, except: [:show, :index]

  def index
    @courses = Course.all
  end

  def show
  end

  def new
    @course = Course.new
  end

  def edit
  end

  def create
    @course = Course.new(course_params)
    @course.user_id = current_user.id
    if @course.save
      redirect_to @course, notice: 'Course was successfully created.'
    else
      render action: 'new'
    end
  end

  def update
    if @course.update(course_params)
      redirect_to @course, notice: 'Course was successfully updated.'
    else
      render action: 'edit'
    end
  end

  def destroy
    @course.destroy
    redirect_to courses_url
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_course
      @course = Course.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def course_params
      params.require(:course).permit(:title, :description, :language, :prerequisites, :duration, :rating)
    end
end