jbuilder

json.items Item.all do |item|
  json.id item.id
  json.created_at item.created_at
end

# {"items":[{"id":1,"created_at":"2015-03-05T22:57:40.558Z"}]}

json.content format_content(@message.content)
json.(@message, :created_at, :updated_at)


  "content": "<p>This is <i>serious</i> monkey business</p>",
  "created_at": "2011-10-29T20:45:28-05:00",
  "updated_at": "2011-10-29T20:45:28-05:00",



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


  "author": {
    "name": "David H.",
    "email_address": "'David Heinemeier Hansson' <[e-mail]>",
    "url": "http://example.com/users/1-david.json"



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

  "visitors": 15,

  "comments": [
    { "content": "Hello everyone!", "created_at": "2011-10-29T20:45:28-05:00" },
    { "content": "To you my good sir!", "created_at": "2011-10-29T20:47:28-05:00" }




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

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


 "attachments": [
    { "filename": "forecast.xls", "url": "http://example.com/downloads/forecast.xls" },
    { "filename": "presentation.pdf", "url": "http://example.com/downloads/presentation.pdf" }
  ]
}

github