pjg · October 6, 2017 08:11 · Jul 30, 2016 · Jul 30, 2016 · Jul 30, 2016
diff --git a/rom-mapper.rb b/rom-mapper.rb
@@ -43,7 +43,7 @@ class Preprocessor < ROM::Mapper
 end
 
 module Repository
-  class Author
+  class Authors
     class << self
       def all
         @@authors ||= preprocessor.call raw_authors
@@ -70,7 +70,7 @@ def gateway
   end
 end
 
-authors = Repository::Author.all
+authors = Repository::Authors.all
 
 p authors
 p authors.first.name

diff --git a/rom-mapper.rb b/rom-mapper.rb
@@ -0,0 +1,82 @@
+require 'rom-mapper'
+
+class BigDecimal
+  def inspect
+    format("#<BigDecimal:%x %s>", object_id, to_s('F'))
+  end
+end
+
+class Gateway
+  def get_authors
+    [
+      {
+        'name' => 'John Doe',
+
+        'books' => [
+          {
+            'title' => 'First book',
+            'price' => '15.99',
+          },
+          {
+            'title' => 'Second book',
+            'price' => '18.99',
+          },
+        ]
+      }
+    ]
+  end
+end
+
+class Preprocessor < ROM::Mapper
+  symbolize_keys true
+
+  model name: 'Author'
+
+  attribute :name
+
+  embedded :books, type: :array do
+    model name: 'Book'
+
+    attribute :title
+    attribute :price, type: :decimal
+  end
+end
+
+module Repository
+  class Author
+    class << self
+      def all
+        @@authors ||= preprocessor.call raw_authors
+      end
+
+      def find_by_name name
+        all.detect { |author| author.name == name }
+      end
+
+      private
+
+      def preprocessor
+        Preprocessor.build
+      end
+
+      def raw_authors
+        @@raw_authors ||= gateway.get_authors
+      end
+
+      def gateway
+        @@gateway ||= Gateway.new
+      end
+    end
+  end
+end
+
+authors = Repository::Author.all
+
+p authors
+p authors.first.name
+p authors.first.books.first.author.name
+
+# outputs:
+# [#<Author:0x007fc30e328060 @name="John Doe", @books=[#<Book:0x007fc30e328560 @title="First book", @price=#<BigDecimal:3fe18719438c 15.99>>, #<Book :0x007fc30e3281f0 @title="Second book", @price=#<BigDecimal:3fe1871941d4 18.99>>]>]
+# "John Doe"
+# rom-mapper.rb:77:in `<main>': undefined method `author' for #<Book:0x007fc30e328560> (NoMethodError)