Update use of links on relationships

app/serializers/api/v1/base_serializer.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module Api
+  module V1
+    class BaseSerializer
+      include JSONAPI::Serializer
+
+      def self.url_helpers
+        Rails.application.routes.url_helpers
+      end
+    end
+  end
+end

app/serializers/api/v1/customer_serializer.rb

@@ -2,12 +2,14 @@
 
 module Api
   module V1
-    class CustomerSerializer
-      include JSONAPI::Serializer
-
+    class CustomerSerializer < BaseSerializer
       attributes :id, :enterprise_id, :first_name, :last_name, :code, :email
 
-      belongs_to :enterprise, record_type: :enterprise, serializer: :id
+      belongs_to :enterprise, links: {
+        related: ->(object) {
+          url_helpers.api_v1_enterprise_url(id: object.enterprise_id)
+        }
+      }
     end
   end
 end

app/serializers/api/v1/enterprise_serializer.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module Api
+  module V1
+    class EnterpriseSerializer < BaseSerializer
+      attributes :id, :name
+
+      has_many :customers, links: {
+        related: ->(object) {
+          url_helpers.api_v1_enterprise_customers_url(enterprise_id: object.id)
+        }
+      }
+    end
+  end
+end

spec/requests/api/v1/customers_spec.rb

@@ -128,6 +128,9 @@ describe "Customers", type: :request do
             "data" => {
               "id" => customer1.enterprise_id.to_s,
               "type" => "enterprise"
+            },
+            "links" => {
+              "related" => "http://test.host/api/v1/enterprises/#{customer1.enterprise_id}"
             }
           }