Complex JSON API Example

complex_json_api_example.rb

# SETUP DB
require 'active_record'
ActiveRecord::Base.establish_connection adapter: 'sqlite3', database: ':memory:'

# SCHEMA
ActiveRecord::Schema.define do
  self.verbose = false
  create_table :users do |t|
    t.string :name
    t.timestamps
  end
  create_table :posts do |t|
    t.string  :body
    t.integer :author_id
    t.timestamps
  end
  create_table :comments do |t|
    t.string  :body
    t.integer :author_id
    t.integer :post_id
    t.timestamps
  end
end

# MODELS
class User < ActiveRecord::Base
  has_many :posts,    foreign_key: :author
  has_many :comments, foreign_key: :author
end
class Post < ActiveRecord::Base
  belongs_to :author, class_name: 'User'
  has_many :comments
end
class Comment < ActiveRecord::Base
  belongs_to :post
  belongs_to :author, class_name: 'User'
end

# DATA
josh  = User.create! name: 'Josh'
yumin = User.create! name: 'Yumin'
gomez = User.create! name: 'Gomez'
Post.create! author: gomez, body: 'first' do |post|
  post.comments.build author: josh, body: "first"
end
Post.create! author: josh, body: 'yo ho ho' do |post|
  post.comments.build author: yumin, body: "yo yo ma"
  post.comments.build author: gomez, body: "yo mama"
end
Post.create! author: josh, body: 'and a bottle of rum'


# JSON API RESOURCES
require 'jsonapi/serializable'
class SerializablePost < JSONAPI::Serializable::Resource
  type 'post'
  attributes :body
  attribute(:date) { @object.created_at }
  belongs_to :author
  has_many :comments do
    data       { @object.comments                           }
    link(:all) { @url_helpers.comment_posts_url(@object.id) }
    meta       { { count: @object.comments.count }          }
  end
  link(:self)  { @url_helpers.post_url(@object.id)          }
  meta         { { featured: true }                         }
end
class SerializableComment < JSONAPI::Serializable::Resource
  type 'comment'
  attributes :body
  attribute(:date) { @object.created_at }
  belongs_to :author
  belongs_to :post
  link(:self) { @url_helpers.comment_url(@object.id) }
end
class SerializableUser < JSONAPI::Serializable::Resource
  type 'user'
  attributes :name
  attribute(:joined) { @object.created_at }
  has_many :posts
  has_many :comments
  link(:self) { @url_helpers.user_url(@object.id) }
end

# THEIR HELPERS
class MyUrlHelper
  def post_url(id)          "/posts/#{id}"            end
  def user_posts_url(id)    "/posts?user=#{id}"       end
  def comment_posts_url(id) "/comments?post_id=#{id}" end
  def comment_url(id)       "/comments/#{id}"         end
  def user_url(id)          "/users/#{id}"            end
end

# RENDER A POST TO JSON (feels weird that it returns an array in included)
renderer = JSONAPI::Serializable::Renderer.new
renderer.render(
  Post.first,
  class: { User: SerializableUser, Comment: SerializableComment, Post: SerializablePost },
  expose: { url_helpers: MyUrlHelper.new },
  include: [:author, comments: [:author]],
  fields: { users: [:name, :email] },
)
# => {:data=>
#      {:id=>"1",
#       :type=>:post,
#       :attributes=>{:body=>"first", :date=>2018-06-28 16:07:23 UTC},
#       :relationships=>
#        {:author=>{:data=>{:type=>:user, :id=>"3"}},
#         :comments=>
#          {:links=>{:all=>"/comments?post_id=1"},
#           :data=>[{:type=>:comment, :id=>"1"}],
#           :meta=>{:count=>1}}},
#       :links=>{:self=>"/posts/1"},
#       :meta=>{:featured=>true}},
#     :included=>
#      [{:id=>"3",
#        :type=>:user,
#        :attributes=>{:name=>"Gomez", :joined=>2018-06-28 16:07:23 UTC},
#        :relationships=>
#         {:posts=>{:meta=>{:included=>false}},
#          :comments=>{:meta=>{:included=>false}}},
#        :links=>{:self=>"/users/3"}},
#       {:id=>"1",
#        :type=>:comment,
#        :attributes=>{:body=>"first", :date=>2018-06-28 16:07:23 UTC},
#        :relationships=>
#         {:author=>{:data=>{:type=>:user, :id=>"1"}},
#          :post=>{:meta=>{:included=>false}}},
#        :links=>{:self=>"/comments/1"}},
#       {:id=>"1",
#        :type=>:user,
#        :attributes=>{:name=>"Josh", :joined=>2018-06-28 16:07:23 UTC},
#        :relationships=>
#         {:posts=>{:meta=>{:included=>false}},
#          :comments=>{:meta=>{:included=>false}}},
#        :links=>{:self=>"/users/1"}}]}