...

fiori/srv/admin-service.cds

@@ -0,0 +1,5 @@
+// Proxy for importing services from bookshop sample
+using from '@capire/bookshop/srv/admin-service';
+using from '@capire/bookshop/srv/cat-service';
+
+annotate AdminService with @impl:'srv/admin-service.js';

fiori/srv/admin-service.js

@@ -0,0 +1,8 @@
+const cds = require('@sap/cds')
+
+module.exports = cds.service.impl (async function() {
+  const {Books} = cds.entities
+  const {ID} = await SELECT.one.from(Books).columns('max(ID) as ID')
+  let newID = ID - ID % 100 + 100
+  this.before ('NEW','Books', req => req.data.ID = ++newID)
+})