Patch of _reduceStock() under @sap/cds 4 (#136)

* Bump to cds 4
* Cosmetics in handler code
  * await and cds.run([...]) instead of Promise.all

Co-authored-by: Christian Georgi <christian.georgi@sap.com>

.npmrc

@@ -1 +1 @@
-@sap:registry=https://npm.sap.com
+registry=https://registry.npmjs.org

package.json

@@ -11,7 +11,7 @@
     "bookshop": "cds watch packages/bookshop"
   },
   "dependencies": {
-    "@sap/cds": "^3",
+    "@sap/cds": "^4",
     "express": "^4"
   },
   "devDependencies": {

packages/bookshop/app/package.json

@@ -3,9 +3,9 @@
   "version": "0.0.1",
   "description": "",
   "dependencies": {
-    "@sap/approuter": "^6"
+    "@sap/approuter": "^8"
   },
   "scripts": {
     "start": "node node_modules/@sap/approuter/approuter.js"
   }
-}
+}

packages/bookshop/package.json

@@ -4,10 +4,10 @@
     "description": "A simple bookshop application, build in a self-contained all-in-one fashion, i.e. w/o reusing other packages.",
     "license": "SAP SAMPLE CODE LICENSE",
     "dependencies": {
-       "@sap/cds": "^3",
-       "express": "^4",
-       "passport": "^0.4.1",
-       "hdb": "^0.17.1"
+        "@sap/cds": "^4",
+        "express": "^4",
+        "hdb": "^0.18.1",
+        "passport": "^0.4.1"
     },
     "scripts": {
         "start": "cds run --in-memory?",

packages/bookshop/srv/cat-service.js

@@ -14,16 +14,20 @@ function _addDiscount2 (each,discount) {
 
 /** Reduce stock of ordered books if available stock suffices */
 async function _reduceStock (req) {
-  const { Items: OrderItems } = req.data
-  return cds.transaction(req) .run (()=> OrderItems.map (order =>
-    UPDATE (Books) .set ('stock -=', order.amount)
-    .where ('ID =', order.book_ID) .and ('stock >=', order.amount)
-  )) .then (all => all.forEach ((affectedRows,i) => {
-    if (affectedRows === 0)  req.error (409,
-      `${OrderItems[i].amount} exceeds stock for book #${OrderItems[i].book_ID}`
-    )
-  }))
+  const { Items: orderItems } = req.data
+  if (!Array.isArray(orderItems))  return
+
+  const all = await cds.transaction(req).run(orderItems.map(item =>
+    UPDATE(Books)
+      .set('stock -=', item.amount)
+      .where('ID =', item.book_ID).and('stock >=', item.amount)
+  ))
+  all.forEach((affectedRows, i) => {
+    if (affectedRows === 0) {
+      req.error(409, `${orderItems[i].amount} exceeds stock for book #${orderItems[i].book_ID}`)
+    }
+  })
+
+ return all
+
 }
-
-
-