jbuilder vs non-jbuilder examples

jbuilder_controller.rb

# app/controllers/messages_controller.rb
class MessagesController < ApplicationController
  def show
    message = Message.find(params[:id])

    respond_to do |format|
      format.json { render :show, locals: { message: message } }
    end
  end
end

jbuilder_view.json.jbuilder

# app/views/messages/show.json.jbuilder
json.content format_content(message.content)
json.(message, :created_at, :updated_at)

json.author do
  json.name message.creator.name.familiar
  json.email_address message.creator.email_address_with_name
  json.url url_for(message.creator, format: :json)
end

if current_user.admin?
  json.visitors calculate_visitors(message)
end

json.comments message.comments, :content, :created_at

json.attachments message.attachments do |attachment|
  json.filename attachment.filename
  json.url url_for(attachment)
end

non_jbuilder_controller.rb

# app/controllers/messages_controller.rb
class MessagesController < ApplicationController
  def show
    message = Message.find(params[:id])

    render json: message_response(message)
  end

  def message_response(message)
    {
      content: format_content(message.content),
      created_at: message.created_at,
      updated_at: message.updated_at,
      # or, if you like the metaprogramming from the jbuilder example:
      #   %I(created_at updated_at).map { |msg| @message.public_send(msg) },

      author: {
        name: message.creator.name.familiar,
        email_address: message.creator.email_address_with_name,
        url: url_for(message.creator, format: :json),
      },

      comments: message.comments.map { |comment|
        {
          content: comment.content,
          created_at: comment.created_at,
        }
      },

      attachments: message.attachments.map { |attachment|
        {
          filename: attachment.filename,
          url: attachment_url(attachment),
        }
      },
    }.tap do |hash|
      # All conditional logic would go here
      if current_user.admin?
        hash[:visitors] = calculate_visitors(message)
      end
    end
  end
end