Aligned content with latest capire docs

bookshop/srv/cat-service.cds

@@ -6,5 +6,5 @@ service CatalogService @(path:'/browse') {
   } excluding { createdBy, modifiedBy };
 
   @requires_: 'authenticated-user'
-  action order (book : Books.ID, amount: Integer);
+  action submitOrder (book : Books.ID, amount: Integer);
 }

bookshop/srv/cat-service.js

@@ -1,23 +1,20 @@
 const cds = require('@sap/cds')
+module.exports = async function (){
 
-/** Service implementation for CatalogService */
-module.exports = cds.service.impl (function() {
-
-  // Get entity definitions from reflected model
-  const { Books } = cds.entities
-
-  // Add some discount for overstocked books
-  this.after ('READ', 'Books', each => {
-    if (each.stock > 111)  each.title += ` -- 11% discount!`
-  })
+  const db = await cds.connect.to('db') // connect to database service
+  const { Books } = db.entities         // get reflected definitions
 
   // Reduce stock of ordered books if available stock suffices
-  this.on ('order', async (req) => {
-    const {UPDATE} = cds.ql(req), {book,amount} = req.data
+  this.on ('submitOrder', async req => {
+    const {book,amount} = req.data
     const n = await UPDATE (Books, book)
-      .where ('stock >=', amount)
-      .set ('stock -=', amount)
+      .with ({ stock: {'-=': amount }})
+      .where ({ stock: {'>=': amount }})
     n > 0 || req.error (409,`${amount} exceeds stock for book #${book}`)
   })
 
-})
+  // Add some discount for overstocked books
+  this.after ('READ','Books', each => {
+    if (each.stock > 111)  each.title += ` -- 11% discount!`
+  })
+}