Merge pull request #6 from tricycle/ar-entity-builder

Add ActiveRecord to Dry::Struct Entity builder

.ruby-version

@@ -1 +1 @@
-2.4.2
+2.5.1

lib/clean_architecture/builders/abstract_active_record_entity_builder.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+module CleanArchitecture
+  module Builders
+    # Helps to take an instance of an AR model and wrap it up in the given Entity
+    # Any columns from the AR model that do not directly map to an attribute on the Entity
+    # can be specified by overriding #attributes_for_entity.
+    class AbstractActiveRecordEntityBuilder
+      # @param [Class] A Dry::Struct based entity that this builder will construct instances of
+      def self.acts_as_builder_for_entity(entity_class)
+        define_method :entity_class do
+          entity_class
+        end
+
+        private :entity_class
+      end
+
+      # @param [ActiveRecord::Base] An ActiveRecord model to map to the entity
+      def initialize(ar_model_instance)
+        @ar_model_instance = ar_model_instance
+      end
+
+      def build
+        entity_class.new(all_attributes_for_entity)
+      end
+
+      private
+
+      attr_reader :ar_model_instance
+
+      def entity_attribute_names
+        @entity_attributes ||= entity_class.schema.keys
+      end
+
+      def ar_attributes_for_entity
+        attributes_for_entity = @ar_model_instance.attributes
+        symbolized_attributes_for_entity = Hash[attributes_for_entity.map{|(key, value)| [key.to_sym, value]}]
+        symbolized_attributes_for_entity.slice(*entity_attribute_names)
+      end
+
+      def attributes_for_entity
+        {}
+      end
+
+      def all_attributes_for_entity
+        ar_attributes_for_entity.merge(attributes_for_entity)
+      end
+    end
+  end
+end

spec/lib/clean_architecture/builders/abstract_active_record_entity_builder_spec.rb

@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require 'clean_architecture/builders/abstract_active_record_entity_builder'
+
+module CleanArchitecture
+  module Builders
+    describe AbstractActiveRecordEntityBuilder do
+      class ExampleModel
+        def age
+          25
+        end
+
+        def attributes
+          {
+            'forename' => 'Samuel',
+            'surname' => 'Giles',
+            'age' => 25
+          }
+        end
+      end
+
+      class ExampleEntitySchema
+        def keys
+          [:forename, :surname, :years_on_planet_earth]
+        end
+      end
+
+      class ExampleEntity
+        def initialize(attributes)
+          @attributes = attributes
+        end
+
+        def self.schema
+          ExampleEntitySchema.new
+        end
+      end
+
+      class ExampleBuilder < AbstractActiveRecordEntityBuilder
+        acts_as_builder_for_entity ExampleEntity
+
+        def attributes_for_entity
+          {
+            years_on_planet_earth: ar_model_instance.age
+          }
+        end
+      end
+
+      let(:builder) { ExampleBuilder.new(ar_model_instance) }
+      let(:ar_model_instance) { ExampleModel.new }
+
+      describe '#build' do
+        subject(:build) { builder.build }
+
+        let(:example_entity) { instance_double(ExampleEntity) }
+
+        before do
+          expect(ExampleEntity)
+            .to receive(:new)
+            .with(
+              forename: 'Samuel',
+              surname: 'Giles',
+              years_on_planet_earth: 25
+            )
+            .and_return(example_entity)
+        end
+
+        it { is_expected.to eq example_entity }
+      end
+    end
+  end
+end