fix: replace Price object in TransactionWasCreated with primitives

src/Billing/Transaction/Application/Create/Command.ts

@@ -12,6 +12,6 @@ export default class CreateCommand implements ICommand {
         price: { amount: number, currency: string },
     ) {
         this.uuid = new TransactionId(uuid);
-        this.price = new Price(price.amount, price.currency);
+        this.price = new Price(String(price.amount), price.currency);
     }
 }

src/Billing/Transaction/Domain/Events/TransactionWasCreated.ts

@@ -1,13 +1,23 @@
 import type { Domain } from "hollywood-js";
-import type Price from "../ValueObject/Price";
 
+/**
+ * Raised when a Transaction is created.
+ *
+ * Carries only primitive data so that the event is safe to serialize, store,
+ * and replay without coupling the event schema to the Price value object.
+ * To reconstruct a Price, call: new Price(event.amount, event.currency)
+ *
+ * Source: Young — "Events are the durable record. They must be self-describing
+ * with primitive data." CQRS Documents (2010).
+ */
 export default class TransactionWasCreated implements Domain.DomainEvent {
     public readonly occurredAt: Date;
 
     constructor(
         public readonly aggregateId: string,
         public readonly product: string,
-        public readonly price: Price,
+        public readonly amount: string,
+        public readonly currency: string,
         occurredAt?: Date,
     ) {
         this.occurredAt = occurredAt ?? new Date();

src/Billing/Transaction/Domain/Transaction.ts

@@ -1,6 +1,6 @@
 import { Domain } from "hollywood-js";
 import TransactionWasCreated from "./Events/TransactionWasCreated";
-import type Price from "./ValueObject/Price";
+import Price from "./ValueObject/Price";
 import type TransactionId from "./ValueObject/TransactionId";
 
 export default class Transaction extends Domain.EventSourcedAggregateRoot {
@@ -11,7 +11,8 @@ export default class Transaction extends Domain.EventSourcedAggregateRoot {
         instance.raise(new TransactionWasCreated(
             uuid.toString(),
             product,
-            price,
+            price.amount,
+            price.currency,
         ));
 
         return instance;
@@ -27,7 +28,7 @@ export default class Transaction extends Domain.EventSourcedAggregateRoot {
 
     private onTransactionWasCreated(event: TransactionWasCreated): void {
         this.product = event.product;
-        this.price = event.price;
+        this.price = new Price(event.amount, event.currency);
     }
 
     get pricing(): Price {

src/Billing/Transaction/Domain/ValueObject/Price.ts

@@ -1,6 +1,11 @@
 import InvalidArgumentException from "../../../Shared/Domain/Exceptions/InvalidArgumentException";
 import { currencies } from "./CurrencyList";
 
+/**
+ * Money value object. Stores the amount as a decimal string to avoid
+ * IEEE 754 floating-point precision loss. Use string arithmetic or a
+ * dedicated decimal library (e.g., decimal.js) for money calculations.
+ */
 export default class Price {
 
     private static validateCurrency(currency: string): void {
@@ -9,21 +14,23 @@ export default class Price {
         }
     }
 
-    private static validateAmount(amount: number): void {
-        if (isNaN(amount)) {
+    private static validateAmount(amount: string): void {
+        const parsed = Number(amount);
+
+        if (isNaN(parsed)) {
             throw new InvalidArgumentException("Amount is not a number");
         }
 
-        if (Math.sign(amount) < 0) {
+        if (parsed < 0) {
             throw new InvalidArgumentException("Negative prices not allowed");
         }
     }
 
-    public readonly amount: number;
+    public readonly amount: string;
     public readonly currency: string;
 
     constructor(
-        amount: number,
+        amount: string,
         currency: string,
     ) {
         Price.validateAmount(amount);

src/Billing/Transaction/Infrastructure/ReadModel/Mapping/Transactions.ts

@@ -10,8 +10,8 @@ export class Transactions {
 
         instance.uuid = event.aggregateId;
         instance.product = event.product;
-        instance.priceAmount = event.price.amount;
-        instance.priceCurrency = event.price.currency;
+        instance.priceAmount = Number(event.amount);
+        instance.priceCurrency = event.currency;
         instance.createdAt = new Date();
 
         return instance;

tests/Apps/HTTP/Transaction/GetOne.test.ts

@@ -27,7 +27,7 @@ describe("GET /transaction/:uuid", () => {
 
   it("GetOne /ae081e7a-ec8c-4ff1-9de5-f70383fe03a7", async () => {
     const txnuuid = "ae081e7a-ec8c-4ff1-9de5-f70383fe03a7";
-    await transactionRepository.save(Transaction.create(new TransactionId(txnuuid), "uuu", new Price(1, "EUR")));
+    await transactionRepository.save(Transaction.create(new TransactionId(txnuuid), "uuu", new Price("1", "EUR")));
 
     const result: any = await api.http.inject({
       method: "GET",

tests/Billing/Transaction/Application/UseCase/Transaction/GetOne.test.ts

@@ -16,7 +16,7 @@ describe("GetOne Transaction", () => {
         await repository.save(Transaction.create(
             new TransactionId("ae081e7a-ec8c-4ff1-9de5-f70383fe03a7"),
             "",
-            new Price(1, "EUR"),
+            new Price("1", "EUR"),
         ));
     });
 

tests/Billing/Transaction/Domain/Transaction/Transaction.test.ts

@@ -6,15 +6,18 @@ import TransactionWasCreated from "@Transaction/Domain/Events/TransactionWasCrea
 
 describe("Transaction", () => {
     test("Create transaction", () => {
-        const price = new Price(2, "EUR");
+        const price = new Price("2", "EUR");
         const transactionID = new TransactionId("ae081e7a-ec8c-4ff1-9de5-f70383fe03a7");
         const instance = Transaction.create(transactionID, "product", price);
         const stream = instance.getUncommittedEvents();
 
+        const event = stream.events[0].event as TransactionWasCreated;
+
         expect(instance.getAggregateRootId().toString()).toBe("ae081e7a-ec8c-4ff1-9de5-f70383fe03a7");
         expect(stream.events[0]).toBeInstanceOf(Domain.DomainMessage);
-        expect((stream.events[0].event as TransactionWasCreated).product).toBe("product");
-        expect((stream.events[0].event as TransactionWasCreated).price).toBe(price);
+        expect(event.product).toBe("product");
+        expect(event.amount).toBe(price.amount);
+        expect(event.currency).toBe(price.currency);
         expect(instance.version()).toBe(0);
     });
 });

tests/Billing/Transaction/Domain/Transaction/ValueObject/Price.test.ts

@@ -3,14 +3,14 @@ import InvalidArgumentException from "@Shared/Domain/Exceptions/InvalidArgumentE
 
 describe("Price", () => {
     test("Create Price VO from Scalars", () => {
-        const instance = new Price(12.5, "EUR");
+        const instance = new Price("12.5", "EUR");
 
         expect(instance.currency).toBe("EUR");
-        expect(instance.amount).toBe(12.5);
+        expect(instance.amount).toBe("12.5");
     });
 
     test("Invalid Currency", () => {
-        const todo = () => new Price(12.5, "GBP");
+        const todo = () => new Price("12.5", "GBP");
         expect(todo).toThrow(InvalidArgumentException);
     });
 });