From 66c43cfa5a4277955b92a1ce381f825c606b7238 Mon Sep 17 00:00:00 2001
From: Simon Gaudek <simon.gaudek@frauscher.com>
Date: Sun, 10 Jul 2022 12:35:45 +0200
Subject: [PATCH] fix(service): Fix addDiscount function

When reading a single book via id, book is not iterable and the function crashes.
---
 package-lock.json           | 12 ++++++------
 src/entities/BookHandler.ts | 21 +++++++++++++++++++--
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index 89a04be..2c7bcc9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1171,7 +1171,7 @@
     "console-control-strings": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/console-control-strings/-/console-control-strings-1.1.0.tgz",
-      "integrity": "sha512-ty/fTekppD2fIwRvnZAVdeOiGd1c7YXEixbgJTNzqcxJWKQnjJ/V1bNEEE6hygpM3WjwHFUVK6HTjWSzV4a8sQ==",
+      "integrity": "sha1-PXz0Rk22RG6mRL9LOVB/mFEAjo4=",
       "dev": true
     },
     "content-disposition": {
@@ -1255,7 +1255,7 @@
     "delegates": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/delegates/-/delegates-1.0.0.tgz",
-      "integrity": "sha512-bd2L678uiWATM6m5Z1VzNCErI3jiGzt6HGY8OVICs40JQq/HALfbyNJmp0UDakEY4pMMaN0Ly5om/B1VI/+xfQ==",
+      "integrity": "sha1-hMbhWbgZBP3KWaDvRM2HDTElD5o=",
       "dev": true
     },
     "depd": {
@@ -1743,7 +1743,7 @@
     "has-unicode": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/has-unicode/-/has-unicode-2.0.1.tgz",
-      "integrity": "sha512-8Rf9Y83NBReMnx0gFzA8JImQACstCYWUplepDa9xprwwtmgEZUF0h/i5xSA625zB/I37EtrswSST6OXxwaaIJQ==",
+      "integrity": "sha1-4Ob+aijPUROIVeCG0Wkedx3iqLk=",
       "dev": true
     },
     "has-yarn": {
@@ -2103,7 +2103,7 @@
     "isexe": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/isexe/-/isexe-2.0.0.tgz",
-      "integrity": "sha512-RHxMLp9lnKHGHRng9QFhRCMbYAcVpn69smSGcq3f36xjgVVWThj4qqLbTLlq7Ssj8B+fIQ1EuCEGI2lKsyQeIw==",
+      "integrity": "sha1-6PvzdNxVb/iUehDcsFctYz8s+hA=",
       "dev": true,
       "optional": true
     },
@@ -2683,7 +2683,7 @@
     "object-assign": {
       "version": "4.1.1",
       "resolved": "https://registry.npmjs.org/object-assign/-/object-assign-4.1.1.tgz",
-      "integrity": "sha512-rJgTQnkUnH1sFw8yT6VSU3zD3sWmu6sZhIseY8VX+GRu3P6F7Fu+JNDoXfklElbLJSnc3FUQHVe4cU5hj+BcUg==",
+      "integrity": "sha1-IQmtx5ZYh8/AXLvUQsrIv7s2CGM=",
       "dev": true
     },
     "object-inspect": {
@@ -3105,7 +3105,7 @@
     "set-blocking": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/set-blocking/-/set-blocking-2.0.0.tgz",
-      "integrity": "sha512-KiKBS8AnWGEyLzofFfmvKwpdPzqiy16LvQfK3yv/fVH7Bj13/wl3JSR1J+rfgRE9q7xUJK4qvgS8raSOeLUehw==",
+      "integrity": "sha1-BF+XgtARrppoA93TgrJDkrPYkPc=",
       "dev": true
     },
     "setprototypeof": {
diff --git a/src/entities/BookHandler.ts b/src/entities/BookHandler.ts
index 9437d33..abce2a8 100644
--- a/src/entities/BookHandler.ts
+++ b/src/entities/BookHandler.ts
@@ -23,8 +23,25 @@ export class BookHandler {
     public async addDiscount(@Entities() book: CatalogService.IBook[], @Req() req: any): Promise<void> {
         console.log("Read Books");
 
-        for (const each of book) {
-            if (each.stock > 111) each.title += ` -- 11% discount!`;
+        const addDiscount = (book) => {
+            if (book.stock > 111) book.title += ` -- 11% discount!`;
+            return book
+        }
+
+        const isIterable = (obj) => {
+            // checks for null and undefined
+            if (obj == null) {
+                return false;
+            }
+            return typeof obj[Symbol.iterator] === 'function';
+        }
+
+        if (isIterable(book)) {
+            for (const each of book) {
+                addDiscount(each);
+            }
+        } else {
+            addDiscount(book);
         }
     }
 }