returning subfolders names

bookshop/srv/admin-service.cds

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+using { sap.capire.bookshop as my } from '../db/schema';
+service AdminService @(requires:'admin') {
+  entity Books as projection on my.Books;
+  entity Authors as projection on my.Authors;
+}

bookshop/srv/admin-service.js

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+const cds = require('@sap/cds')
+
+module.exports = cds.service.impl (function(){
+  this.before ('NEW','Authors', genid)
+  this.before ('NEW','Books', genid)
+})
+
+/** Generate primary keys for target entity in request */
+async function genid (req) {
+  const {ID} = await cds.tx(req).run (SELECT.one.from(req.target).columns('max(ID) as ID'))
+  req.data.ID = ID - ID % 100 + 100 + 1
+}

bookshop/srv/cat-service.cds

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+using { sap.capire.bookshop as my } from '../db/schema';
+service CatalogService @(path:'/browse') {
+
+  @readonly entity Books as SELECT from my.Books { *,
+    author.name as author
+  } excluding { createdBy, modifiedBy };
+
+  @readonly entity ListOfBooks as SELECT from Books
+  excluding { descr };
+
+  @requires: 'authenticated-user'
+  action submitOrder ( book: Books:ID, amount: Integer ) returns { stock: Integer };
+  event OrderedBook : { book: Books:ID; amount: Integer; buyer: String };
+}

bookshop/srv/cat-service.js

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+const cds = require('@sap/cds')
+const { Books } = cds.entities ('sap.capire.bookshop')
+
+class CatalogService extends cds.ApplicationService { init(){
+
+  // Reduce stock of ordered books if available stock suffices
+  this.on ('submitOrder', async req => {
+    const {book,amount} = req.data, tx = cds.tx(req)
+    let {stock} = await tx.read('stock').from(Books,book)
+    if (stock >= amount) {
+      await tx.update (Books,book).with ({ stock: stock -= amount })
+      await this.emit ('OrderedBook', { book, amount, buyer:req.user.id })
+      return { stock }
+    }
+    else return 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!`
+    }
+  })
+
+  return super.init()
+}}
+
+module.exports = { CatalogService }