rom-http-repo-aggregate.rb

require 'bundler/inline'
require 'json'
require 'uri'
require 'net/http'

gemfile(true) do
  gem 'inflecto'
  gem 'rom', github: 'rom-rb/rom'
  gem 'rom-support', github: 'rom-rb/rom-support'
  gem 'rom-http', github: 'rom-rb/rom-http'
  gem 'rom-repository', github: 'rom-rb/rom-repository'
end

class RequestHandler
  def call(dataset)
    uri = URI(dataset.uri)
    uri.path = dataset.absolute_path
    uri.query = URI.encode_www_form(dataset.params)

    http = Net::HTTP.new(uri.host, uri.port)
    request_klass = Net::HTTP.const_get(Inflecto.classify(dataset.request_method))

    request = request_klass.new(uri.request_uri)
    dataset.headers.each_with_object(request) do |(header, value), request|
      request[header.to_s] = value
    end

    response = http.request(request)
  end
end

class ResponseHandler
  def call(response, dataset)
    Array([JSON.parse(response.body, symbolize_names: true)]).flatten
  end
end

class Users < ROM::Relation[:http]
  schema(:users) do
    attribute :id, ROM::Types::Int.meta(primary_key: true)
    attribute :name, ROM::Types::String
    attribute :username, ROM::Types::String
    attribute :email, ROM::Types::String
    attribute :phone, ROM::Types::String
    attribute :website, ROM::Types::String
  end

  def by_id(id)
    with_path(id.to_s)
  end
end

class Posts < ROM::Relation[:http]
  schema(:posts) do
    attribute :id, ROM::Types::Int.meta(primary_key: true)
    attribute :userId, ROM::Types::Int.meta(alias: :user_id)
    attribute :title, ROM::Types::String
    attribute :body, ROM::Types::String
  end

  def by_id(id)
    with_path(id.to_s)
  end

  def for_user(user)
    with_options(
      base_path: 'users',
      path: "#{user.first[:id]}/posts"
    )
  end
end

class UserRepository < ROM::Repository[:users]
  relations :posts

  def find(id)
    users.by_id(id).first
  end

  def find_with_posts(user_id)
    users.by_id(user_id).combine_children(many: posts.for_user).first
  end
end

configuration = ROM::Configuration.new(:http, {
  uri: 'http://jsonplaceholder.typicode.com',
  headers: {
    Accept: 'application/json'
  },
  request_handler: RequestHandler.new,
  response_handler: ResponseHandler.new
})
configuration.register_relation(Users)
configuration.register_relation(Posts)
container = ROM.container(configuration)

UserRepository.new(container).find_with_posts(1)