cds init bookshop --add samples cd bookshop npm install 

npm add -D @sap/cds-dk cds serve all --watch --in-memory --to rest 

### Get book data from the catalog GET http://localhost:4004/rest/catalog/Books 

curl http://localhost:4004/rest/catalog/Books 

using my.bookshop as my from '../db/data-model'; service CatalogService { @readonly entity Books as projection on my.Books; action submitOrder(book : Books:ID, quantity : Integer); } 

const cds = require("@sap/cds"); class CatalogService extends cds.ApplicationService { init() { const { Books } = cds.entities("my.bookshop"); // Reduce stock of ordered books if available stock suffices this.on("submitOrder", async (req) => { const { book, quantity } = req.data; let { stock, title } = await SELECT`stock, title`.from(Books, book); const remaining = stock - quantity; if (remaining < 0) { return req.reject(409, `${quantity} exceeds stock for book #${book}`); } await UPDATE(Books, book).with({ stock: remaining }); return { ID: book, stock: remaining }; }); return super.init(); } } module.exports = { CatalogService }; 

### Get stock data from the catalog GET http://localhost:4004/rest/catalog/Books ### Submit an order POST http://localhost:4004/rest/catalog/submitOrder HTTP/1.1 Content-Type: application/json { "book": 1, "quantity": 95 } 

curl -X POST -d '{"book":1,"quantity":95}' \ -H 'Content-Type: application/json' \ http://localhost:4004/rest/catalog/submitOrder 

npm add @sendgrid/mail 

{ "SENDGRID_API_KEY": "<Replace with API Key>", "SENDGRID_SENDER": "<Replace with Sender's Email Address>", "SENDGRID_RECEIVER": "<Replace with Receiver's Email Address>" } 

const cds = require("@sap/cds"); const sgMail = require("@sendgrid/mail"); sgMail.setApiKey(process.env.SENDGRID_API_KEY); class CatalogService extends cds.ApplicationService { init() { const { Books } = cds.entities("my.bookshop"); // Reduce stock of ordered books if available stock suffices this.on("submitOrder", async (req) => { const { book, quantity } = req.data; let { stock, title } = await SELECT`stock, title`.from(Books, book); const remaining = stock - quantity; if (remaining < 0) { return req.reject(409, `${quantity} exceeds stock for book #${book}`); } await UPDATE(Books, book).with({ stock: remaining }); if (remaining < 10) { const msg = { to: process.env.SENDGRID_RECEIVER, from: process.env.SENDGRID_SENDER, subject: 'Low Stock Alert', text: `A customer just ordered ${quantity}x "${title}" and there are only ${remaining} left in stock.`, html: `<strong>A customer just ordered ${quantity}x "${title}" and there are only ${remaining} left in stock.</strong>`, }; sgMail .send(msg) .then(() => console.log('Email sent')) .catch((error) => console.error(error)); } return { ID: book, stock: remaining }; }); return super.init(); } } module.exports = { CatalogService }; 

const msg = { to: process.env.SENDGRID_RECEIVER, from: process.env.SENDGRID_SENDER, subject: 'Low Stock Alert', text: `A customer just ordered ${quantity}x "${title}" and there are only ${remaining} left in stock. Please respond with "Yes" `+ `if you would like to restock now.`, html: `<strong>A customer just ordered ${quantity}x "${title}" and there are only ${remaining} left in stock. Please respond with "Yes" `+ `if you would like to restock now.</strong>`, }; 

npm add multer 

const cds = require("@sap/cds"); const multer = require('multer'); const sgMail = require("@sendgrid/mail"); sgMail.setApiKey(process.env.SENDGRID_API_KEY); const upload = multer({ dest: 'uploads/' }) cds.on("bootstrap", (app) => { app.post( "/sendgridInbound", upload.none(), async (req, res) => { console.log(`Received message ${req.body.text}.`) res.end("ok"); } ); }); 

const cds = require("@sap/cds"); const multer = require("multer"); const sgMail = require("@sendgrid/mail"); sgMail.setApiKey(process.env.SENDGRID_API_KEY); const upload = multer({ dest: "uploads/" }); async function collectBookDetails(sender, message) { if (message.includes("Yes")) { const restockPattern = /Yes (\d+)/i; const lastOrderPattern = /(\d+)x/; const titlePattern = /"(.*?)"/; const restock = message.match(restockPattern) ? +message.match(restockPattern)[1] : undefined; const originalMessage = message.match(/>(.*)/g).join(""); try { const lastOrder = +originalMessage.match(lastOrderPattern)[1]; const title = originalMessage.match(titlePattern)[1]; const { Books } = cds.entities("my.bookshop"); const books = await cds.read(Books).where({ title }); return { valid: true, restock: restock || lastOrder, book: books[0], }; } catch (err) { //regex didn't find a last order or book title return { valid: false }; } } return { valid: false, }; } cds.on("bootstrap", (app) => { app.post("/sendgridInboud", upload.none(), async (req, res) => { const { from } = JSON.parse(req.body.envelope), to = req.body.to, parsed = await collectBookDetails(from, req.body.text); if ( from === process.env.SENDGRID_RECEIVER && to === process.env.SENDGRID_SENDER && parsed.valid ) { const newStock = parsed.book.stock + parsed.restock; const { Books } = cds.entities("my.bookshop"); await UPDATE(Books, parsed.book.ID).with({ stock: newStock }); sgMail.send({ to: process.env.SENDGRID_RECEIVER, from: process.env.SENDGRID_SENDER, subject: `RE: ${req.body.subject}`, text: `Successfully restocked "${parsed.book.title}". Current stock: ${newStock}`, html: `<strong>Successfully restocked "${parsed.book.title}". Current stock: ${newStock}</strong>`, }); } else { const msg = { to: process.env.SENDGRID_RECEIVER, from: process.env.SENDGRID_SENDER, subject: `RE: ${req.body.subject}`, text: `Failed to restock. Please reply with "Yes <additionalStock>"`, html: `<strong>Failed to restock. Please reply with "Yes <additionalStock>"</strong>`, }; sgMail.send(msg); } res.end("ok"); }); }); 

ngrok http 4004