Showing errors for a form partial

articles_controller.rb

class ArticlesController < ActionController::Base
  def show
    @article = Article.find(params[:id])
    # ... bunch of stuff to set up template display
  end
end

comments_controller.rb

class CommentsController < ActionController::Base
  def create
    post = Article.find(params[:article_id])

    if @comment = articles.comments.create(params[:comment])
      redirect_to article
    else
      # If validations fail, I need to display the original articles#show
      # with the form showing @comment.errors
    end
  end
end