Separated reviewed and reviews

reviewed/db/schema.cds

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+//
+//  Extending Books with Reviews
+//
+
+using { sap.capire.bookshop.Books } from '@capire/bookshop';
+using { ReviewsService.Reviews } from '@capire/reviews';
+
+extend Books with {
+  /** Access to detailed collection of Reviews */
+  reviews : Composition of many Reviews on reviews.subject = $self.ID;
+  /** Average rating */
+  rating : Reviews.rating;
+}
+
+// Temporary workaround for cap/issues#4112:
+annotate Reviews with @cds.autoexpose;

reviewed/package.json

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+{
+  "name": "@capire/bookshop-with-reviews",
+  "version": "1.0.0",
+  "dependencies": {
+    "@capire/bookshop": "../bookshop",
+    "@capire/reviews": "../reviews",
+    "@sap/cds": "^3.33.1",
+    "express": "^4.17.1"
+  },
+  "cds": {
+    "requires": {
+      "db": {
+        "kind": "sql"
+      },
+      "ReviewsService": {
+        "kind": "odata", "model": "@capire/reviews"
+      },
+      "messaging": {
+        "kind": "file-based-messaging"
+      }
+    }
+  }
+}

reviewed/server.js

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+////////////////////////////////////////////////////////////////////////////
+//
+//   This is an example of using a project-local server.js to intercept
+//   the default bootstrapping process.
+//
+
+const cds = require ('@sap/cds')
+
+// Mashup services after all are served...
+cds.once('served', async()=>{
+
+    // react on event messages from reviews service
+    const ReviewsService = await cds.connect.to ('ReviewsService')
+    const db = await cds.connect.to ('db')
+
+    // reflect entities required below...
+    const { Books } = db.entities('sap.capire.bookshop')
+    const { Reviews } = ReviewsService.entities
+
+    ReviewsService.on ('reviewed', (msg) => {
+        console.debug ('> received:', msg.event, msg.data)
+        const { subject, rating } = msg.data
+        const tx = db.tx (msg) // TODO: db.tx(msg) fully implemented?
+        return tx.update (Books,subject) .with ({rating})
+    })
+
+    // delegate requests to read reviews to ReviewsService
+    const CatalogService = await cds.connect.to ('CatalogService')
+    CatalogService.impl (srv => srv.on ('READ', 'Books/reviews', (req) => {
+        console.debug ('> delegating to ReviewsService')
+        const [ id ] = req.params
+        const tx = ReviewsService.tx(req)
+        return tx.read (Reviews) .where ({ subject: String(id) })
+        .columns (req.query.SELECT.columns)
+    }))
+
+})
+
+// Other bootstrapping events you could hook in to...
+/* eslint-disable no-unused-vars */
+cds.on('bootstrap',(app) => {/* ... */})
+cds.on('loaded', (model) => {/* ... */})
+cds.on('connect', (srv) => {/* ... */})
+cds.on('serving', (srv) => {/* ... */})
+cds.once('listening', ({server,url}) => {/* ... */})
+
+
+// Delegate bootstrapping to built-in server.js
+module.exports = cds.server
+
+// Monkey-patching older releases
+if (cds.version < '3.33.4') cds.once('listening', ()=> cds.emit('served'))
+
+// Launch server if started directly from command-line
+if (!module.parent)  cds.server()

reviewed/test/requests.http

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+#################################################
+#
+#   To ReviewsService
+#
+# move the right down:
+@reviews-service = http://localhost:4004/reviews
+@reviews-service = http://localhost:5005/reviews
+
+### Get all reviews
+GET {{reviews-service}}/Reviews
+
+### Add a new review (with random rating)
+POST {{reviews-service}}/Reviews
+Content-Type: application/json;IEEE754Compatible=true
+
+{"subject":"201", "title":"boo"}
+
+
+
+#################################################
+#
+#   Bookshop Requests involving reviews
+#   (both in-process as well as separate one)
+#
+
+@bookshop = http://localhost:4004
+
+### Request to CatalogService > delegated to ReviewsService
+GET {{bookshop}}/browse/Books(201)/reviews?
+&$select=rating,date,reviewer,title
+
+### Alternative OData URL
+GET {{bookshop}}/browse/Books/201/reviews?
+&$select=rating,date,reviewer,title
+
+###
+GET {{bookshop}}/browse/Books(201)?
+&$select=ID,title,rating
+&$expand=reviews
+# Note: the $expand only works in case of ReviewsService in same process