Create a ContentIdAlias on PUT Content

A `ContentIdAlias` will be created when making a request to this
endpoint when the API consumer submits the
`[:details][:content_id_alias]` parameter, as long as they're updating
the correct document type (currently only possible for email addresses
and postal addresses).

app/commands/v2/put_content.rb

@@ -16,6 +16,7 @@ def call
         edition = create_or_update_edition
         set_timestamps(edition)
 
+        create_content_id_alias
         update_content_dependencies(edition)
 
         orphaned_links = link_diff_between(
@@ -98,6 +99,17 @@ def create_links(edition)
         end
       end
 
+      def create_content_id_alias
+        content_id_alias = payload.dig(:details, :content_id_alias)
+        return unless content_id_alias && EmbeddedContentFinderService::SUPPORTED_DOCUMENT_TYPES.include?(payload[:document_type])
+
+        if ContentIdAlias.find_by(name: content_id_alias)
+          raise CommandError.new(code: 422, message: "ContentIdAlias with that name already exists")
+        end
+
+        ContentIdAlias.create!(name: content_id_alias, content_id: payload[:content_id])
+      end
+
       def fetch_embedded_content(edition)
         return [] if edition[:details].nil?
 

spec/commands/v2/put_content_spec.rb

@@ -104,6 +104,79 @@
       )
     end
 
+    describe "linking a content_id to a human readable alias" do
+      context "when updating a content block type" do
+        let(:content_block_payload) do
+          {
+            content_id:,
+            locale: "en",
+            schema_name: "content_block_email_address",
+            document_type: "content_block_email_address",
+            title: "Government Digital Service - General contact",
+            description: "General contact email address for Government Digital Service",
+            details: {
+              content_id_alias: "gds-general",
+              email_address: "[email protected]",
+            },
+            publishing_app: "whitehall",
+          }
+        end
+
+        context "and including a content_id_alias" do
+          it "creates a ContentIdAlias" do
+            expect(ContentIdAlias).to receive(:create!).with(name: content_block_payload[:details][:content_id_alias], content_id:)
+            described_class.call(content_block_payload)
+          end
+
+          context "but a matching ContentIdAlias already exists" do
+            before do
+              create(:content_id_alias, content_id:, name: content_block_payload[:details][:content_id_alias])
+            end
+
+            it "raises an error" do
+              expect {
+                described_class.call(content_block_payload)
+              }.to raise_error(CommandError) { |error|
+                     expect(error.code).to eq(422)
+                   }
+            end
+          end
+        end
+
+        context "and not including a content_id_alias" do
+          before do
+            validator = double(:validator, validate: true)
+            allow(Commands::V2::PutContentValidator).to receive(:new)
+              .and_return(validator)
+          end
+
+          it "does not create a ContentIdAlias" do
+            content_block_payload = {
+              content_id:,
+              locale: "en",
+              schema_name: "content_block_email_address",
+              document_type: "content_block_email_address",
+              title: "Government Digital Service - General contact",
+              description: "General contact email address for Government Digital Service",
+              details: {
+                email_address: "[email protected]",
+              },
+              publishing_app: "whitehall",
+            }
+            expect(ContentIdAlias).not_to receive(:create!)
+            described_class.call(content_block_payload)
+          end
+        end
+      end
+
+      context "when updating any other type" do
+        it "does not create a ContentIdAlias" do
+          expect(ContentIdAlias).not_to receive(:create!)
+          described_class.call(payload)
+        end
+      end
+    end
+
     context "when the 'downstream' parameter is false" do
       it "does not send to the downstream draft worker" do
         expect(DownstreamDraftJob).not_to receive(:perform_async_in_queue)