def create
    @sponsored_post = SponsoredPost.new
    @sponsored_post.title = params[:sponsored_post][:title]
    @sponsored_post.body = params[:sponsored_post][:body]
    @sponsored_post.price = params[:sponsored_post][:price]
    topic = Topic.find(params[:topic_id])
    @sponsored_post.topic = topic

    if @sponsored_post.save
      flash[:notice] = "Sponsored post was saved."
      redirect_to [topic, @sponsored_post]
    else
      flash[:error] = "There was an error saving the sponsored post. Please try again."
      render :new
    end
  end