refactor model user

app/controllers/api/v1/users_controller.rb

@@ -3,10 +3,13 @@ class Api::V1::UsersController < ApplicationController
   before_action :set_user
   before_action :set_purchase_option, only: [:purchase]
 
+  class AlreadyPurchasedError < StandardError; end
+
   # POST /api/v1/users/:id/purchase
   # Params: { "purchase_option_id": 1 }
   def purchase
-    @user.purchase(@purchase_option)
+    raise AlreadyPurchasedError if @user.is_in_library?(@purchase_option.content)
+    Purchase.create(user: @user, purchase_option: @purchase_option)
     render json: @user.library
   end
 

app/controllers/application_controller.rb

@@ -1,12 +1,12 @@
 class ApplicationController < ActionController::API
-  rescue_from User::AlreadyPurchasedError, with: :render_method_not_allowed
+  rescue_from Api::V1::UsersController::AlreadyPurchasedError, with: :render_method_not_allowed
   rescue_from ActiveRecord::RecordNotFound, with: :render_not_found_response
 
-  def render_not_found_response(exception)
-    render json: { error: exception.message }, status: :not_found
-  end
-
   def render_method_not_allowed(exception)
     render json: { error: exception.message }, status: 405
   end
+
+  def render_not_found_response(exception)
+    render json: { error: exception.message }, status: :not_found
+  end
 end

app/models/user.rb

@@ -1,23 +1,12 @@
 class User < ApplicationRecord
 
-  class AlreadyPurchasedError < StandardError; end
-
   has_many :purchases
 
   def library
     self.purchases.select {|p| p.alive? }.sort_by(&:remaining_time)
   end
 
-  def purchase(purchase_option)
-    if is_in_library?(purchase_option.content)
-      raise AlreadyPurchasedError
-    else
-      self.purchases << Purchase.create(purchase_option: purchase_option)
-    end
-  end
-
-  private
-
+  # check by title
   def is_in_library?(content)
     library.any? {|purchase| purchase.content.title == content.title }
   end

spec/models/user_spec.rb

@@ -20,10 +20,6 @@
     expect(user.library.size).to eql(3)
   end
 
-  it "can't purchase a content that is in the library" do
-    expect{ user.purchase(user.library.first.purchase_option) }.to raise_error(User::AlreadyPurchasedError)
-  end
-
   it "library is ordered by purchase's remaining time" do
     user.purchases.last.update(created_at: 1.day.ago)