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)
+    )
+  })
+})