Introduced bookstore composite app

bookstore/srv/mashup.cds

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+////////////////////////////////////////////////////////////////////////////
+//
+//    Enhancing bookshop with Reviews and Orders provided through
+//    respective reuse packages and services
+//
+
+using { sap.capire.bookshop.Books } from '@capire/bookshop';
+
+//
+//  Extend Books with access to Reviews and average ratings
+//
+using { ReviewsService.Reviews } from '@capire/reviews';
+extend Books with {
+  reviews : Composition of many Reviews on reviews.subject = $self.ID;
+  rating  : Decimal;
+  numberOfReviews : Integer;
+}
+
+
+//
+//  Extend Orders with Books as Products
+//
+using { sap.capire.orders.Orders_Items } from '@capire/orders';
+extend Orders_Items with {
+  book : Association to Books on product.ID = book.ID
+}
+
+
+// Add orders fiori app (in case of embedded orders service)
+using from '@capire/orders/app/fiori';

bookstore/srv/mashup.js

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+////////////////////////////////////////////////////////////////////////////
+//
+//    Mashing up bookshop services with required services...
+//
+module.exports = async()=>{ // called by server.js
+
+  const cds = require('@sap/cds')
+  const CatalogService = await cds.connect.to ('CatalogService')
+  const ReviewsService = await cds.connect.to ('ReviewsService')
+  const OrdersService = await cds.connect.to ('OrdersService')
+  const db = await cds.connect.to ('db')
+
+  // reflect entity definitions used below...
+  const { Books } = db.entities ('sap.capire.bookshop')
+
+  //
+  // Delegate requests to read reviews to the ReviewsService
+  // Note: prepend is neccessary to intercept generic default handler
+  //
+  CatalogService.prepend (srv => srv.on ('READ', 'Books/reviews', (req) => {
+    console.debug ('> delegating request to ReviewsService')
+    const [id] = req.params, { columns, limit } = req.query.SELECT
+    return ReviewsService.tx(req).read ('Reviews',columns).limit(limit).where({subject:String(id)})
+  }))
+
+  //
+  // Create an order with the OrdersService when CatalogService signals a new order
+  //
+  CatalogService.on ('OrderedBook', async (msg) => {
+    const { book, quantity, buyer } = msg.data
+    const { title, price } = await db.tx(msg).read (Books, book, b => { b.title, b.price })
+    return OrdersService.tx(msg).create ('Orders').entries({
+      OrderNo: 'Order at '+ (new Date).toLocaleString(),
+      Items: [{ product:{ID:`${book}`}, title, price, quantity }],
+      buyer, createdBy: buyer
+    })
+  })
+
+  //
+  // Update Books' average ratings when ReviewsService signals updatd reviews
+  //
+  ReviewsService.on ('reviewed', (msg) => {
+    console.debug ('> received:', msg.event, msg.data)
+    const { subject, count, rating } = msg.data
+    return UPDATE(Books,subject).with({ numberOfReviews:count, rating })
+    // ^ Note: the framework will execute this and take care for db.tx
+  })
+
+  //
+  // Reduce stock of ordered books for orders are created from Orders admin UI
+  //
+  OrdersService.on ('OrderChanged', (msg) => {
+    console.debug ('> received:', msg.event, msg.data)
+    const { product, deltaQuantity } = msg.data
+    return UPDATE (Books) .where ('ID =', product)
+    .and ('stock >=', deltaQuantity)
+    .set ('stock -=', deltaQuantity)
+  })
+}

bookstore/srv/swagger-ui.js

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+
+// -----------------------------------------------------------------------
+// Adding Swagger UI - see https://cap.cloud.sap/docs/advanced/openapi
+const cds = require ('@sap/cds')
+try {
+  const cds_swagger = require ('cds-swagger-ui-express')
+  cds.once ('bootstrap', app => app.use (cds_swagger()) )
+} catch (err) {
+  if (err.code !== 'MODULE_NOT_FOUND')  throw err
+}