chore: add method to automatically determine the model associations required to be eager loaded for a decorator

lib/pact_broker/api/decorators/base_decorator.rb

@@ -4,6 +4,7 @@
 require "pact_broker/api/decorators/decorator_context"
 require "pact_broker/api/decorators/format_date_time"
 require "pact_broker/string_refinements"
+require "pact_broker/hash_refinements"
 
 module PactBroker
   module Api
@@ -14,15 +15,17 @@ class BaseDecorator < Roar::Decorator
         include PactBroker::Api::PactBrokerUrls
         include FormatDateTime
         using PactBroker::StringRefinements
+        using PactBroker::HashRefinements
 
+        # Call this method to automatically camelize property names without
+        # having to define an :as each time.
         def self.camelize_property_names
           @camelize = true
         end
 
-        def self.eager_load_associations
-          representable_attrs.values.select{ | attr| attr[:collection] || attr[:embedded] }.collect{ |attr| attr[:name].to_sym }
-        end
-
+        # Overrides the default property method to add a camelised :as option
+        # when camelize_property_names has been called for this decorator.
+        # @override
         def self.property(name, options={}, &block)
           if options.delete(:camelize) || @camelize
             camelized_name = name.to_s.camelcase(false).to_sym
@@ -31,6 +34,39 @@ def self.property(name, options={}, &block)
             super
           end
         end
+
+        # Returns the names of the model associations to eager load for use with this decorator
+        # @return [Array<Symbol>]
+        def self.eager_load_associations
+          if is_collection_resource?
+            collection_item_decorator_class.eager_load_associations
+          else
+            embedded_and_collection_attribute_names
+          end
+        end
+
+        # Returns true if this class is a decorator for a collection
+        # @return [true, false]
+        def self.is_collection_resource?
+          representable_attrs_without_links = representable_attrs.to_h.without("links")
+          representable_attrs_without_links.size == 1 &&
+            representable_attrs_without_links.values.first[:collection] &&
+            representable_attrs_without_links.values.first[:extend]
+        end
+        private_class_method :is_collection_resource?
+
+        # Returns the names of the model attributes that are collections, embedded or nested items
+        # @return [Array<Symbol>]
+        def self.embedded_and_collection_attribute_names
+          representable_attrs.values.select{ | attr| attr[:collection] || attr[:embedded] || attr[:nested] }.collect{ |attr| attr[:name].to_sym }
+        end
+        private_class_method :embedded_and_collection_attribute_names
+
+        # @return [Class] The decorator class used to decorate the items in the collection
+        def self.collection_item_decorator_class
+          representable_attrs.to_h.without("links").values.first[:extend].call
+        end
+        private_class_method :collection_item_decorator_class
       end
     end
   end

spec/lib/pact_broker/api/decorators/base_decorator_spec.rb

@@ -0,0 +1,41 @@
+require "pact_broker/api/decorators/base_decorator"
+
+module PactBroker
+  module Api
+    module Decorators
+      describe BaseDecorator do
+        class TestItemDecorator < BaseDecorator
+          collection :children
+          property :foo, embedded: true
+
+          property :bar do
+            property :name
+          end
+          property :other
+        end
+
+        class TestItemsDecorator < BaseDecorator
+          collection :entries, as: :items, embedded: true, :extend => TestItemDecorator
+
+          link :self do
+            "http://foo"
+          end
+        end
+
+        describe "eager_load_associations" do
+          context "for an individual resource" do
+            it "returns the attributes that are collections or embedded" do
+              expect(TestItemDecorator.eager_load_associations).to eq [:children, :foo, :bar]
+            end
+          end
+
+          context "for a collection decorator" do
+            it "returns the eager_load_associations of the class used to decorate the collection items" do
+              expect(TestItemsDecorator.eager_load_associations).to eq [:children, :foo, :bar]
+            end
+          end
+        end
+      end
+    end
+  end
+end

spec/lib/pact_broker/api/decorators/integration_decorator_spec.rb

@@ -5,79 +5,87 @@ module PactBroker
   module Api
     module Decorators
       describe IntegrationDecorator do
-        before do
-          allow(integration_decorator).to receive(:dashboard_url_for_integration).and_return("/dashboard")
-          allow(integration_decorator).to receive(:matrix_url).and_return("/matrix")
-          allow(integration_decorator).to receive(:group_url).and_return("/group")
-        end
+        describe ".eager_load_associations" do
+          subject { IntegrationDecorator }
 
-        let(:integration) do
-          instance_double(PactBroker::Integrations::Integration,
-            consumer: consumer,
-            provider: provider,
-            verification_status_for_latest_pact: pseudo_branch_verification_status
-          )
+          its(:eager_load_associations) { is_expected.to eq [:consumer, :provider] }
         end
-        let(:consumer) { double("consumer", name: "the consumer") }
-        let(:provider) { double("provider", name: "the provider") }
-        let(:pseudo_branch_verification_status) { double("pseudo_branch_verification_status", to_s: "some_status") }
 
-        let(:options) { { user_options: { base_url: "http://example.org" } } }
-        let(:expected_hash) do
-          {
-            "consumer" => {
-              "name" => "the consumer"
-            },
-            "provider" => {
-              "name" => "the provider"
-            },
-            "_links" => {
-              "pb:dashboard" => {
-                "href" => "/dashboard"
+        describe "#to_json" do
+          before do
+            allow(integration_decorator).to receive(:dashboard_url_for_integration).and_return("/dashboard")
+            allow(integration_decorator).to receive(:matrix_url).and_return("/matrix")
+            allow(integration_decorator).to receive(:group_url).and_return("/group")
+          end
+
+          let(:integration) do
+            instance_double(PactBroker::Integrations::Integration,
+              consumer: consumer,
+              provider: provider,
+              verification_status_for_latest_pact: pseudo_branch_verification_status
+            )
+          end
+          let(:consumer) { double("consumer", name: "the consumer") }
+          let(:provider) { double("provider", name: "the provider") }
+          let(:pseudo_branch_verification_status) { double("pseudo_branch_verification_status", to_s: "some_status") }
+
+          let(:options) { { user_options: { base_url: "http://example.org" } } }
+          let(:expected_hash) do
+            {
+              "consumer" => {
+                "name" => "the consumer"
               },
-              "pb:matrix" => {
-                "title" => "Matrix of pacts/verification results for the consumer and the provider",
-                "href" => "/matrix"
+              "provider" => {
+                "name" => "the provider"
               },
-              "pb:group" => {
-                "href" => "/group"
+              "_links" => {
+                "pb:dashboard" => {
+                  "href" => "/dashboard"
+                },
+                "pb:matrix" => {
+                  "title" => "Matrix of pacts/verification results for the consumer and the provider",
+                  "href" => "/matrix"
+                },
+                "pb:group" => {
+                  "href" => "/group"
+                }
               }
             }
-          }
-        end
+          end
 
-        let(:integration_decorator) { IntegrationDecorator.new(integration) }
-        let(:json) { integration_decorator.to_json(options) }
-        subject { JSON.parse(json) }
+          let(:integration_decorator) { IntegrationDecorator.new(integration) }
+          let(:json) { integration_decorator.to_json(options) }
+          subject { JSON.parse(json) }
 
-        it "generates a hash" do
-          expect(subject).to match_pact expected_hash
-        end
+          it "generates a hash" do
+            expect(subject).to match_pact expected_hash
+          end
 
-        it "generates the correct link for the dashboard" do
-          expect(integration_decorator).to receive(:dashboard_url_for_integration).with(
-            "the consumer",
-            "the provider",
-            "http://example.org"
-          )
-          subject
-        end
+          it "generates the correct link for the dashboard" do
+            expect(integration_decorator).to receive(:dashboard_url_for_integration).with(
+              "the consumer",
+              "the provider",
+              "http://example.org"
+            )
+            subject
+          end
 
-        it "generates the correct link for the matrix" do
-          expect(integration_decorator).to receive(:matrix_url).with(
-            "the consumer",
-            "the provider",
-            "http://example.org"
-          )
-          subject
-        end
+          it "generates the correct link for the matrix" do
+            expect(integration_decorator).to receive(:matrix_url).with(
+              "the consumer",
+              "the provider",
+              "http://example.org"
+            )
+            subject
+          end
 
-        it "generates the correct group url for the matrix" do
-          expect(integration_decorator).to receive(:group_url).with(
-            "the consumer",
-            "http://example.org"
-          )
-          subject
+          it "generates the correct group url for the matrix" do
+            expect(integration_decorator).to receive(:group_url).with(
+              "the consumer",
+              "http://example.org"
+            )
+            subject
+          end
         end
       end
     end