Topic controller code

class TopicsController < ApplicationController
  def index
    @topics = Topic.all
  end

  # GET /topics/1
  # GET /topics/1.json
  def show
    @topic = Topic.find(params[:id])
  end

  # GET /topics/new
  def new
    @topic = Topic.new
  end

  # POST /topics
# POST /topics.json
def create
  @topic = Topic.new(topic_params)

  respond_to do |format|
    if @topic.save
      format.html { redirect_to @topic, notice: 'Topic was successfully created.' }
      format.json { render :show, status: :created, location: @topic }
    else
      format.html { render :new }
      format.json { render json: @topic.errors, status: :unprocessable_entity }
    end
  end
end

  private

    # Never trust parameters from the scary internet, only allow the white list through.
    def topic_params
      params.require(:topic).permit(:title, :description)
    end
end