Homework task 1

.gitignore

@@ -41,3 +41,5 @@ coverage
 config/settings.local.yml
 config/settings/*.local.yml
 config/environments/*.local.yml
+
+.byebug_history

Gemfile

@@ -52,3 +52,5 @@ end
 group :development do
   gem 'web-console'
 end
+
+gem "alba", "~> 3.5"

Gemfile.lock

@@ -95,6 +95,8 @@ GEM
       uri (>= 0.13.1)
     addressable (2.8.7)
       public_suffix (>= 2.0.2, < 7.0)
+    alba (3.5.0)
+      ostruct (~> 0.6)
     arbre (1.7.0)
       activesupport (>= 3.0.0)
       ruby2_keywords (>= 0.0.2)
@@ -448,6 +450,7 @@ DEPENDENCIES
   activeadmin
   activeadmin_addons
   activerecord-import
+  alba (~> 3.5)
   bundler-audit
   capybara
   config
@@ -479,4 +482,4 @@ DEPENDENCIES
   web-console
 
 BUNDLED WITH
-   2.5.18
+   2.5.3

app/controllers/api/v1/books_controller.rb

@@ -0,0 +1,16 @@
+module Api
+  module V1
+    class BooksController < ApplicationController
+      def index
+        permitted_params = index_params.to_h
+        books = Books::IndexInteractor.call(page: permitted_params[:page])
+        render json: { data: Books::Index::BookResource.new(books).to_h }
+      end
+
+      private
+      def index_params
+        params.permit(:page)
+      end
+    end
+  end
+end

app/interactors/api/v1/books/index_interactor.rb

@@ -0,0 +1,25 @@
+module Api
+  module V1
+    module Books
+      class IndexInteractor < ApplicationInteractor
+        def initialize(page:)
+          @page = Integer(page, exception: false) || 1
+        end
+
+        def call
+          Book.includes(:authors).order(created_at: :asc).offset(offset).limit(per_page)
+        end
+
+        private
+
+        def offset
+          per_page * (@page - 1)
+        end
+
+        def per_page
+          Settings.app.items_per_page
+        end
+      end
+    end
+  end
+end

app/interactors/application_interactor.rb

@@ -0,0 +1,5 @@
+class ApplicationInteractor
+  def self.call(*, **)
+    new(*, **).call
+  end
+end

app/serializers/api/v1/books/index/author_resource.rb

@@ -0,0 +1,13 @@
+module Api
+  module V1
+    module Books
+      module Index
+        class AuthorResource
+          include Alba::Resource
+
+          attributes :id, :first_name, :middle_name, :last_name
+        end
+      end
+    end
+  end
+end

app/serializers/api/v1/books/index/book_resource.rb

@@ -0,0 +1,15 @@
+module Api
+  module V1
+    module Books
+      module Index
+        class BookResource
+          include Alba::Resource
+
+          attributes :id, :title, :series, :serno
+
+          many :authors, resource: AuthorResource
+        end
+      end
+    end
+  end
+end

bin/rspec

@@ -0,0 +1,28 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+#
+# This file was generated by Bundler.
+#
+# The application 'rspec' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../Gemfile", __dir__)
+ENV["RAILS_ENV"] = "test"
+
+bundle_binstub = File.expand_path("bundle", __dir__)
+
+if File.file?(bundle_binstub)
+  if File.read(bundle_binstub, 300).include?("This file was generated by Bundler")
+    load(bundle_binstub)
+  else
+    abort("Your `bin/bundle` was not generated by Bundler, so this binstub cannot run.
+Replace `bin/bundle` by running `bundle binstubs bundler --force`, then run this command again.")
+  end
+end
+
+require "rubygems"
+require "bundler/setup"
+
+load Gem.bin_path("rspec-core", "rspec")

config/database.yml

@@ -17,6 +17,7 @@ development:
 
 test:
   <<: *default
+  <<: *postgre
   database: library_test
 
 production:

config/initializers/alba.rb

@@ -0,0 +1 @@
+Alba.inflector = nil

config/routes.rb

@@ -27,4 +27,10 @@
   # Render dynamic PWA files from app/views/pwa/*
   get 'service-worker' => 'rails/pwa#service_worker', as: :pwa_service_worker
   get 'manifest' => 'rails/pwa#manifest', as: :pwa_manifest
+
+  namespace :api do
+    namespace :v1 do
+      resources :books, only: [:index]
+    end
+  end
 end

docs/arch.md

@@ -0,0 +1,55 @@
+```plantuml
+@startuml
+actor Client as C
+participant Routing as R
+participant Controller as Cntr
+participant ServiceObject as Inter
+
+entity Model as M
+
+
+participant Serializer as S
+database DB as DB
+
+
+C -> R
+activate R
+
+
+R -> Cntr
+activate Cntr
+deactivate R
+
+
+Cntr -> Inter
+activate Inter
+
+
+Inter -> M
+activate M
+
+M -> DB
+activate DB
+
+return
+return
+return
+
+...
+
+
+Cntr -> S
+activate S
+
+return
+Cntr -> C
+deactivate Cntr
+
+
+
+
+
+
+@enduml
+
+```

spec/controllers/api/v1/books_controller_spec.rb

@@ -0,0 +1,73 @@
+describe Api::V1::BooksController do
+  describe "GET #index" do
+    subject(:call) { get :index }
+
+    before do
+      Settings.app.items_per_page = 2
+    end
+
+    context "when there are no books" do
+      it "returns empty array" do
+        subject
+
+        expect(response).to have_http_status 200
+        expect(JSON.parse(response.body, symbolize_names: true)).to eq(data: [])
+      end
+    end
+
+    context "when there are 6 books" do
+      let!(:books) { create_list(:book, 6) }
+
+      it "returns first 2 books" do
+        subject
+
+        expect(response).to have_http_status 200
+        expect(JSON.parse(response.body, symbolize_names: true)).to eq(
+          data: [
+            {
+              authors: [],
+              id: books[0].id,
+              title: books[0].title,
+              series: nil,
+              serno: nil
+            },
+            {
+              authors: [],
+              id: books[1].id,
+              title: books[1].title,
+              series: nil,
+              serno: nil
+            }
+          ])
+      end
+
+      context "when requested page is 2" do
+        subject(:call) { get :index, params: { page: 2 } }
+
+
+        it "returns third and fourth books" do
+          subject
+
+          expect(response).to have_http_status 200
+          expect(JSON.parse(response.body, symbolize_names: true)).to eq(
+            data: [
+              {
+                authors: [],
+                id: books[2].id,
+                title: books[2].title,
+                series: nil,
+                serno: nil
+              },
+              {
+                authors: [],
+                id: books[3].id,
+                title: books[3].title,
+                series: nil,
+                serno: nil
+              }
+            ])
+        end
+      end
+    end
+  end
+end