Fixed error handling

Author: oskardudycz

samples/from_crud_to_eventsourcing/src/core/http.ts

@@ -34,7 +34,8 @@ export const isWeakETag = (etag: ETag): etag is WeakETag => {
 
 export const getWeakETagValue = (etag: ETag): WeakETag => {
   const weak = WeakETagRegex.exec(etag);
-  if (weak == null || weak.length == 0) throw ETagErrors.WRONG_WEAK_ETAG_FORMAT;
+  if (weak == null || weak.length == 0)
+    throw new Error(ETagErrors.WRONG_WEAK_ETAG_FORMAT);
   return weak[1] as WeakETag;
 };
 
@@ -66,7 +67,7 @@ export const getWeakETagValueFromHeader = (
   }
 
   if (!isWeakETag(etag)) {
-    throw ETagErrors.WRONG_WEAK_ETAG_FORMAT;
+    throw new Error(ETagErrors.WRONG_WEAK_ETAG_FORMAT);
   }
 
   return getWeakETagValue(etag);
@@ -89,7 +90,7 @@ export const getExpectedRevisionFromIfMatch = (request: ApiRequest): bigint => {
   const revision = getExpectedRevision(request, HeaderNames.IF_MATCH);
 
   if (revision === undefined) {
-    throw ETagErrors.MISSING_HEADER;
+    throw new Error(ETagErrors.MISSING_HEADER);
   }
 
   return revision;

samples/from_crud_to_eventsourcing/src/core/postgres.ts

@@ -12,11 +12,15 @@ let db: ConnectionPool;
 export const getPostgres = (): ConnectionPool => {
   if (!db) {
     if (!config.postgres.connectionString) {
-      throw 'Postgres connection string not set. Please define "DATABASE_URL" environment variable';
+      throw new Error(
+        'Postgres connection string not set. Please define "DATABASE_URL" environment variable'
+      );
     }
 
     if (!config.postgres.schemaName) {
-      throw 'Postgres schema name string not set. Please define "DATABASE_SCHEMA" environment variable';
+      throw new Error(
+        'Postgres schema name string not set. Please define "DATABASE_SCHEMA" environment variable'
+      );
     }
 
     db = createConnectionPool({
@@ -65,7 +69,7 @@ export const assertUpdated = async <T>(
   const result = await update();
 
   if (result.length === 0) {
-    throw PostgresErrors.FAILED_TO_UPDATE_ROW;
+    throw new Error(PostgresErrors.FAILED_TO_UPDATE_ROW);
   }
 
   return result;
@@ -77,7 +81,7 @@ export const assertFound = async <T>(
   const result = await find();
 
   if (result === null) {
-    throw PostgresErrors.ROW_NOT_FOUND;
+    throw new Error(PostgresErrors.ROW_NOT_FOUND);
   }
 
   return result;

samples/from_crud_to_eventsourcing/src/core/validation.ts

@@ -14,21 +14,21 @@ export const enum ValidationErrors {
 
 export const assertNotEmptyString = (value: unknown): string => {
   if (typeof value !== 'string' || value.length === 0) {
-    throw ValidationErrors.NOT_A_NONEMPTY_STRING;
+    throw new Error(ValidationErrors.NOT_A_NONEMPTY_STRING);
   }
   return value;
 };
 
 export const assertStringOrUndefined = (value: unknown): string | undefined => {
   if (value != null && typeof value !== 'string') {
-    throw ValidationErrors.NOT_A_STRING_OR_UNDEFINED;
+    throw new Error(ValidationErrors.NOT_A_STRING_OR_UNDEFINED);
   }
   return value ?? undefined;
 };
 
 export const assertPositiveNumber = (value: unknown): number => {
   if (typeof value !== 'number' || value <= 0) {
-    throw ValidationErrors.NOT_A_POSITIVE_NUMBER;
+    throw new Error(ValidationErrors.NOT_A_POSITIVE_NUMBER);
   }
   return value;
 };
@@ -41,26 +41,26 @@ export const assertPositiveNumberOrUndefined = (
 
 export const assertUnsignedBigInt = (value: string): bigint => {
   if (value === undefined) {
-    throw ValidationErrors.NOT_AN_UNSIGNED_BIGINT;
+    throw new Error(ValidationErrors.NOT_AN_UNSIGNED_BIGINT);
   }
 
   const number = BigInt(value);
   if (number < 0) {
-    throw ValidationErrors.NOT_AN_UNSIGNED_BIGINT;
+    throw new Error(ValidationErrors.NOT_AN_UNSIGNED_BIGINT);
   }
   return number;
 };
 
 export const assertDateOrUndefined = (value: unknown): Date | undefined => {
   if (value != null && typeof value !== 'string') {
-    throw ValidationErrors.NOT_A_DATE_OR_UNDEFINED;
+    throw new Error(ValidationErrors.NOT_A_DATE_OR_UNDEFINED);
   }
   return value ? new Date(value) : undefined;
 };
 
 export const assertArray = (value: unknown): [] => {
   if (!Array.isArray(value)) {
-    throw ValidationErrors.NOT_AN_ARRAY;
+    throw new Error(ValidationErrors.NOT_AN_ARRAY);
   }
   return value as [];
 };

samples/from_crud_to_eventsourcing/src/eventsourced/core/streams.ts

@@ -11,24 +11,18 @@ import {
   StreamingRead,
 } from '@eventstore/db-client';
 
-export type ApplyEvent<Entity, E extends EventType> = (
-  currentState: Entity | undefined,
-  event: RecordedEvent<E>
-) => Entity;
-
 export const StreamAggregator =
   <Entity, StreamEvents extends EventType>(
-    when: ApplyEvent<Entity, StreamEvents>
+    when: (currentState: Entity, event: RecordedEvent<StreamEvents>) => Entity
   ) =>
   async (
     eventStream: StreamingRead<ResolvedEvent<StreamEvents>>
   ): Promise<Entity> => {
-    let currentState: Entity | undefined = undefined;
+    let currentState = {} as Entity;
     for await (const { event } of eventStream) {
       if (!event) continue;
       currentState = when(currentState, event);
     }
-    if (currentState == null) throw 'oh no';
     return currentState;
   };
 
@@ -40,7 +34,9 @@ let eventStore: EventStoreDBClient;
 
 export function getEventStore(): EventStoreDBClient {
   if (!config.eventStoreDB.connectionString) {
-    throw 'EventStoreDB connection string not set. Please define "ESDB_CONNECTION_STRING" environment variable';
+    throw new Error(
+      'EventStoreDB connection string not set. Please define "ESDB_CONNECTION_STRING" environment variable'
+    );
   }
 
   if (!eventStore) {

samples/from_crud_to_eventsourcing/src/eventsourced/shoppingCarts/productItem.ts

@@ -72,7 +72,7 @@ export const assertProductItemExists = (
   const current = findProductItem(productItems, productId);
 
   if (!current || current.quantity < quantity) {
-    throw ShoppingCartErrors.PRODUCT_ITEM_NOT_FOUND;
+    throw new Error(ShoppingCartErrors.PRODUCT_ITEM_NOT_FOUND);
   }
 
   return current;

samples/from_crud_to_eventsourcing/src/eventsourced/shoppingCarts/shoppingCart.ts

@@ -101,22 +101,25 @@ export interface ShoppingCart {
 
 export const enum ShoppingCartErrors {
   OPENED_EXISTING_CART = 'OPENED_EXISTING_CART',
-  CART_IS_ALREADY_CLOSED = 'CART_IS_ALREADY_CLOSED',
-  CART_NOT_FOUND = 'CART_NOT_FOUND',
+  CART_IS_NOT_OPENED = 'CART_IS_NOT_OPENED',
   USER_DOES_NOT_EXISTS = 'USER_DOES_NOT_EXISTS',
+  NO_PRODUCTS_ITEMS = 'NO_PRODUCTS_ITEMS',
   PRODUCT_ITEM_NOT_FOUND = 'PRODUCT_ITEM_NOT_FOUND',
   UNKNOWN_EVENT_TYPE = 'UNKNOWN_EVENT_TYPE',
 }
 
 export const toShoppingCartStreamName = (shoppingCartId: string) =>
   `shopping_cart-${shoppingCartId}`;
 
-export const assertShoppingCartIsNotClosed = (shoppingCart: ShoppingCart) => {
-  if (
-    (shoppingCart.status & ShoppingCartStatus.Closed) ===
-    ShoppingCartStatus.Closed
-  ) {
-    throw ShoppingCartErrors.CART_IS_ALREADY_CLOSED;
+export const assertShoppingCartIsOpened = (shoppingCart: ShoppingCart) => {
+  if (shoppingCart.status !== ShoppingCartStatus.Opened) {
+    throw new Error(ShoppingCartErrors.CART_IS_NOT_OPENED);
+  }
+};
+
+export const assertHasProductItems = (shoppingCart: ShoppingCart) => {
+  if (shoppingCart.productItems.length === 0) {
+    throw new Error(ShoppingCartErrors.NO_PRODUCTS_ITEMS);
   }
 };
 
@@ -128,19 +131,14 @@ export const getShoppingCart = StreamAggregator<
   ShoppingCart,
   ShoppingCartEvent
 >((currentState, event) => {
-  if (event.type === 'shopping-cart-opened') {
-    if (currentState != null) throw ShoppingCartErrors.OPENED_EXISTING_CART;
-    return {
-      id: event.data.shoppingCartId,
-      openedAt: new Date(event.data.openedAt),
-      productItems: [],
-      status: ShoppingCartStatus.Opened,
-    };
-  }
-
-  if (currentState == null) throw ShoppingCartErrors.CART_NOT_FOUND;
-
   switch (event.type) {
+    case 'shopping-cart-opened':
+      return {
+        id: event.data.shoppingCartId,
+        openedAt: new Date(event.data.openedAt),
+        productItems: [],
+        status: ShoppingCartStatus.Opened,
+      };
     case 'product-item-added-to-shopping-cart':
       return {
         ...currentState,
@@ -164,7 +162,8 @@ export const getShoppingCart = StreamAggregator<
       };
     default: {
       const _: never = event;
-      throw ShoppingCartErrors.UNKNOWN_EVENT_TYPE;
+      console.error(`Unknown event type %s`, event);
+      return currentState;
     }
   }
 });
@@ -205,7 +204,7 @@ export const addProductItemToShoppingCart = async (
 ): Promise<ProductItemAddedToShoppingCart> => {
   const shoppingCart = await getShoppingCart(events);
 
-  assertShoppingCartIsNotClosed(shoppingCart);
+  assertShoppingCartIsOpened(shoppingCart);
 
   const pricedProductItem = await getPricedProduct(productItem);
 
@@ -234,7 +233,7 @@ export const removeProductItemFromShoppingCart = async (
 ): Promise<ProductItemRemovedFromShoppingCart> => {
   const shoppingCart = await getShoppingCart(events);
 
-  assertShoppingCartIsNotClosed(shoppingCart);
+  assertShoppingCartIsOpened(shoppingCart);
 
   const current = assertProductItemExists(
     shoppingCart.productItems,
@@ -272,7 +271,8 @@ export const confirmShoppingCart = async (
 ): Promise<ShoppingCartConfirmed> => {
   const shoppingCart = await getShoppingCart(events);
 
-  assertShoppingCartIsNotClosed(shoppingCart);
+  assertShoppingCartIsOpened(shoppingCart);
+  assertHasProductItems(shoppingCart);
 
   const user = await getUserData(userId);
 

samples/from_crud_to_eventsourcing/src/eventsourced/shoppingCarts/shoppingCartDetails.ts

@@ -47,7 +47,7 @@ export const projectToShoppingCartItem = (
       return projectShoppingCartConfirmed(db, event, streamRevision);
     default: {
       const _: never = event;
-      throw ShoppingCartErrors.UNKNOWN_EVENT_TYPE;
+      throw new Error(ShoppingCartErrors.UNKNOWN_EVENT_TYPE);
     }
   }
 };