http-repo.rb

require 'rom'
require 'rom-http'
require 'rom-repository'
require 'json'
require 'uri'
require 'net/http'

class RequestHandler
  def call(dataset)
    uri = URI(dataset.uri)
    uri.path = "/#{dataset.name}/#{dataset.path}"
    uri.query = URI.encode_www_form(dataset.params)

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

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

    http.request(request)
  end
end

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

ROM.use :auto_registration

ROM.setup(:http, {
  uri: 'http://jsonplaceholder.typicode.com',
  headers: {
    Accept: 'application/json'
  },
  request_handler: RequestHandler.new,
  response_handler: ResponseHandler.new
})

class Posts < ROM::Relation[:http]
  dataset :posts

  use :view
  use :key_inference

  view(:base, ["userId", "id", "title", "body"]) do
    self
  end

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

class PostRepository < ROM::Repository::Base
  relations :posts

  def by_id(id)
    posts.by_id(id)
  end
end

container = ROM.finalize.env

post_repo = PostRepository.new(container)

puts post_repo.by_id(1).to_a.inspect
# [#<ROM::Struct[Post] userId=1 id=1 title="sunt aut facere repellat provident occaecati excepturi optio reprehenderit" body="quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit mo
lestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto">]