Use updatedAt from database for event timestamp

Author: stevebux

lambdas/letter-updates-transformer/src/__tests__/letter-updates-transformer.test.ts

@@ -13,7 +13,7 @@ import { Deps } from "../deps";
 import { EnvVars } from "../env";
 import mapLetterToCloudEvent from "../mappers/letter-mapper";
 import { LetterStatus } from "../../../api-handler/src/contracts/letters";
-import { LetterWithSupplierId } from "../types";
+import { LetterForEventPub } from "../types";
 
 // Make crypto return consistent values, since we"re calling it in both prod and test code and comparing the values
 const realCrypto = jest.requireActual("crypto");
@@ -148,7 +148,7 @@ describe("letter-updates-transformer Lambda", () => {
     it("does not publish invalid letter data", async () => {
       const handler = createHandler(mockedDeps);
       const oldLetter = generateLetter("ACCEPTED");
-      const newLetter = { id: oldLetter.id } as LetterWithSupplierId;
+      const newLetter = { id: oldLetter.id } as LetterForEventPub;
 
       const testData = generateKinesisEvent([
         generateModifyRecord(oldLetter, newLetter),
@@ -252,33 +252,31 @@ describe("letter-updates-transformer Lambda", () => {
   });
 });
 
-function generateLetter(
-  status: LetterStatus,
-  id?: string,
-): LetterWithSupplierId {
+function generateLetter(status: LetterStatus, id?: string): LetterForEventPub {
   return {
     id: id || "1",
     status,
     specificationId: "spec1",
     supplierId: "supplier1",
     groupId: "group1",
+    updatedAt: "2025-12-10T11:13:54Z",
   };
 }
 
 function generateLetters(
   numLetters: number,
   status: LetterStatus,
-): LetterWithSupplierId[] {
-  const letters: LetterWithSupplierId[] = Array.from({ length: numLetters });
+): LetterForEventPub[] {
+  const letters: LetterForEventPub[] = Array.from({ length: numLetters });
   for (let i = 0; i < numLetters; i++) {
     letters[i] = generateLetter(status, String(i + 1));
   }
   return letters;
 }
 
 function generateModifyRecord(
-  oldLetter: LetterWithSupplierId,
-  newLetter: LetterWithSupplierId,
+  oldLetter: LetterForEventPub,
+  newLetter: LetterForEventPub,
 ): DynamoDBRecord {
   const oldImage = Object.fromEntries(
     Object.entries(oldLetter).map(([key, value]) => [key, { S: value }]),

lambdas/letter-updates-transformer/src/letter-updates-transformer.ts

@@ -12,7 +12,7 @@ import {
 import { LetterEvent } from "@nhsdigital/nhs-notify-event-schemas-supplier-api/src";
 import mapLetterToCloudEvent from "./mappers/letter-mapper";
 import { Deps } from "./deps";
-import { LetterSchemaWithSupplierId, LetterWithSupplierId } from "./types";
+import { LetterForEventPub, LetterSchemaForEventPub } from "./types";
 
 // SNS PublishBatchCommand supports up to 10 messages per batch
 const BATCH_SIZE = 10;
@@ -62,9 +62,9 @@ function isChanged(record: DynamoDBRecord, property: string): boolean {
   return oldValue?.S !== newValue?.S;
 }
 
-function extractNewLetter(record: DynamoDBRecord): LetterWithSupplierId {
+function extractNewLetter(record: DynamoDBRecord): LetterForEventPub {
   const newImage = record.dynamodb?.NewImage!;
-  return LetterSchemaWithSupplierId.parse(unmarshall(newImage as any));
+  return LetterSchemaForEventPub.parse(unmarshall(newImage as any));
 }
 
 function* generateBatches(events: LetterEvent[]) {

lambdas/letter-updates-transformer/src/mappers/__tests__/letter-mapper.test.ts

@@ -12,9 +12,8 @@ describe("letter-mapper", () => {
       status: "PRINTED",
       reasonCode: "R02",
       reasonText: "Reason text",
+      updatedAt: "2025-11-24T15:55:18.000Z",
     } as Letter;
-    jest.useFakeTimers().setSystemTime(new Date("2025-11-24T15:55:18Z"));
-
     const event = mapLetterToCloudEvent(letter);
 
     // Check it conforms to the letter event schema - parse will throw an error if not
@@ -42,7 +41,5 @@ describe("letter-mapper", () => {
         event: event.id,
       },
     });
-
-    jest.useRealTimers();
   });
 });

lambdas/letter-updates-transformer/src/mappers/letter-mapper.ts

@@ -1,12 +1,11 @@
 import { LetterEvent } from "@nhsdigital/nhs-notify-event-schemas-supplier-api/src";
 import { randomBytes, randomUUID } from "node:crypto";
 import eventSchemaPackage from "@nhsdigital/nhs-notify-event-schemas-supplier-api/package.json";
-import { LetterWithSupplierId } from "../types";
+import { LetterForEventPub } from "../types";
 
 export default function mapLetterToCloudEvent(
-  letter: LetterWithSupplierId,
+  letter: LetterForEventPub,
 ): LetterEvent {
-  const now = new Date().toISOString();
   const eventId = randomUUID();
   const dataschemaversion = eventSchemaPackage.version;
   return {
@@ -34,10 +33,10 @@ export default function mapLetterToCloudEvent(
         event: eventId,
       },
     },
-    time: now,
+    time: letter.updatedAt,
     datacontenttype: "application/json",
     traceparent: `00-${randomBytes(16).toString("hex")}-${randomBytes(8).toString("hex")}-01`,
-    recordedtime: now,
+    recordedtime: letter.updatedAt,
     severitynumber: 2,
     severitytext: "INFO",
   };

lambdas/letter-updates-transformer/src/types.ts

@@ -2,8 +2,9 @@ import { LetterSchemaBase, SupplierSchema } from "@internal/datastore";
 import { idRef } from "@internal/helpers";
 import { z } from "zod";
 
-export const LetterSchemaWithSupplierId = LetterSchemaBase.extend({
+export const LetterSchemaForEventPub = LetterSchemaBase.extend({
   supplierId: idRef(SupplierSchema, "id"),
+  updatedAt: z.string(),
 });
 
-export type LetterWithSupplierId = z.infer<typeof LetterSchemaWithSupplierId>;
+export type LetterForEventPub = z.infer<typeof LetterSchemaForEventPub>;