jbuilder

by rails

rails / jbuilder

Jbuilder: generate JSON objects with a Builder-style DSL

3.8K Stars 371 Forks Last release: about 1 month ago (v2.10.1) MIT License 677 Commits 65 Releases

Available items

No Items, yet!

The developer of this repository has not created any items for sale yet. Need a bug fixed? Help with integration? A different license? Create a request here:

Jbuilder

Jbuilder gives you a simple DSL for declaring JSON structures that beats manipulating giant hash structures. This is particularly helpful when the generation process is fraught with conditionals and loops. Here's a simple example:

# 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

This will build the following structure:

{
  "content": "

This is serious monkey business

", "created_at": "2011-10-29T20:45:28-05:00", "updated_at": "2011-10-29T20:45:28-05:00",

"author": { "name": "David H.", "email_address": "'David Heinemeier Hansson' ", "url": "http://example.com/users/1-david.json" },

"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" } ],

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

To define attribute and structure names dynamically, use the

set!
method:
json.set! :author do
  json.set! :name, 'David'
end

=> {"author": { "name": "David" }}

To merge existing hash or array to current context:

hash = { author: { name: "David" } }
json.post do
  json.title "Merge HOWTO"
  json.merge! hash
end

=> "post": { "title": "Merge HOWTO", "author": { "name": "David" } }

Top level arrays can be handled directly. Useful for index and other collection actions.

# @comments = @post.comments

json.array! @comments do |comment| next if comment.marked_as_spam_by?(current_user)

json.body comment.body json.author do json.first_name comment.author.first_name json.last_name comment.author.last_name end end

=> [ { "body": "great post...", "author": { "first_name": "Joe", "last_name": "Bloe" }} ]

You can also extract attributes from array directly.

# @people = People.all

json.array! @people, :id, :name

=> [ { "id": 1, "name": "David" }, { "id": 2, "name": "Jamie" } ]

Jbuilder objects can be directly nested inside each other. Useful for composing objects.

class Person
  # ... Class Definition ... #
  def to_builder
    Jbuilder.new do |person|
      person.(self, :name, :age)
    end
  end
end

class Company

... Class Definition ...

def to_builder Jbuilder.new do |company| company.name name company.president president.to_builder end end end

company = Company.new('Doodle Corp', Person.new('John Stobs', 58)) company.to_builder.target!

=> {"name":"Doodle Corp","president":{"name":"John Stobs","age":58}}

You can either use Jbuilder stand-alone or directly as an ActionView template language. When required in Rails, you can create views a la show.json.jbuilder (the json is already yielded):

# Any helpers available to views are available to the builder
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

You can use partials as well. The following will render the file

views/comments/_comments.json.jbuilder
, and set a local variable
comments
with all this message's comments, which you can use inside the partial.
json.partial! 'comments/comments', comments: @message.comments

It's also possible to render collections of partials:

json.array! @posts, partial: 'posts/post', as: :post

or

json.partial! 'posts/post', collection: @posts, as: :post

or

json.partial! partial: 'posts/post', collection: @posts, as: :post

or

json.comments @post.comments, partial: 'comments/comment', as: :comment

The

as: :some_symbol
is used with partials. It will take care of mapping the passed in object to a variable for the partial. If the value is a collection (either implicitly or explicitly by using the
collection:
option, then each value of the collection is passed to the partial as the variable
some_symbol
. If the value is a singular object, then the object is passed to the partial as the variable
some_symbol
.

Be sure not to confuse the

as:
option to mean nesting of the partial. For example:
 # Use the default `views/comments/_comment.json.jbuilder`, putting @comment as the comment local variable.
 # Note, `comment` attributes are "inlined".
 json.partial! @comment, as: :comment

is quite different than:

 # comment attributes are nested under a "comment" property
json.comment do
  json.partial! "/comments/comment.json.jbuilder", comment: @comment
end

You can pass any objects into partial templates with or without

:locals
option.
json.partial! 'sub_template', locals: { user: user }

or

json.partial! 'sub_template', user: user

You can explicitly make Jbuilder object return null if you want:

json.extract! @post, :id, :title, :content, :published_at
json.author do
  if @post.anonymous?
    json.null! # or json.nil!
  else
    json.first_name @post.author_first_name
    json.last_name @post.author_last_name
  end
end

To prevent Jbuilder from including null values in the output, you can use the

ignore_nil!
method:
json.ignore_nil!
json.foo nil
json.bar "bar"
# => { "bar": "bar" }

Fragment caching is supported, it uses

Rails.cache
and works like caching in HTML templates:
json.cache! ['v1', @person], expires_in: 10.minutes do
  json.extract! @person, :name, :age
end

You can also conditionally cache a block by using

cache_if!
like this:
json.cache_if! !admin?, ['v1', @person], expires_in: 10.minutes do
  json.extract! @person, :name, :age
end

If you are rendering fragments for a collection of objects, have a look at

jbuilder_cache_multi
gem. It uses fetch_multi (>= Rails 4.1) to fetch multiple keys at once.

Keys can be auto formatted using

key_format!
, this can be used to convert keynames from the standard ruby_format to camelCase:
json.key_format! camelize: :lower
json.first_name 'David'

=> { "firstName": "David" }

You can set this globally with the class method

key_format
(from inside your environment.rb for example):
Jbuilder.key_format camelize: :lower

Contributing to Jbuilder

Jbuilder is the work of many contributors. You're encouraged to submit pull requests, propose features and discuss issues.

See CONTRIBUTING.

License

Jbuilder is released under the MIT License.

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.