Some more code, cosmetics

packages/bookshop/srv/admin-service.js

@@ -0,0 +1,19 @@
+const cds = require('@sap/cds')
+
+/** Service implementation for AdminService */
+module.exports = cds.service.impl(srv => {
+  const { OrderItems } = srv.entities ('sap.capire.bookshop')
+
+  // on-the-fly calculate the total Order price based on the OrderItems' netAmounts
+  srv.after (['READ','EDIT'], 'Orders', async (orders, req) => {
+    const ordersByID = Array.isArray(orders)
+      ? orders.reduce ((all,o) => { (all[o.ID] = o).total=0; return all },{})
+      : { [orders.ID]: orders }
+    return cds.transaction(req) .run (
+      SELECT.from(OrderItems) .columns ('parent_ID', 'netAmount')
+       .where ({ parent_ID: {in: Object.keys(ordersByID)} })
+    ) .then (items =>
+      items.forEach (item => ordersByID [item.parent_ID] .total += item.netAmount)
+    )
+  })
+})

packages/bookshop/srv/cat-service.js

@@ -14,15 +14,15 @@ function _addDiscount2 (each,discount) {
 }
 /** Reduce stock of ordered books if available stock suffices */
 async function _reduceStock (req) {
-  const { Items: OrderItems } = req.data
-  // req.on('failed', () => { console.debug ('>>> failed for order', req.data.ID) })
+  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) => {
+  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}`
+      `${orderItems[i].amount} exceeds stock for book #${orderItems[i].book_ID}`
     )
   }))
 }