Add new notification subscription

backend/index.js

@@ -2,29 +2,58 @@ const express = require('express');
 const bodyParser = require('body-parser');
 const { graphqlExpress, graphiqlExpress } = require('apollo-server-express');
 const { makeExecutableSchema } = require('graphql-tools');
+const { PubSub } = require('graphql-subscriptions');
+const cors = require('cors');
+const { execute, subscribe } = require('graphql');
+const { createServer } = require('http');
+const { SubscriptionServer } = require('subscriptions-transport-ws');
+
+const pubsub = new PubSub();
+const NOTIFICATION_SUBSCRIPTION_TOPIC = 'newNotifications';
 
 const notifications = [];
 const typeDefs = `
   type Query { notifications: [Notification] }
   type Notification { label: String }
   type Mutation { pushNotification(label: String!): Notification }
+  type Subscription { newNotification: Notification }
 `;
 const resolvers = {
   Query: { notifications: () => notifications },
   Mutation: {
       pushNotification: (root, args) => {
         const newNotification = { label: args.label };
         notifications.push(newNotification);
+        pubsub.publish(NOTIFICATION_SUBSCRIPTION_TOPIC, { newNotification: newNotification });
 
         return newNotification;
       },
   },
+  Subscription: {
+    newNotification: {
+      subscribe: () => pubsub.asyncIterator(NOTIFICATION_SUBSCRIPTION_TOPIC)
+    }
+  },
 };
 const schema = makeExecutableSchema({ typeDefs, resolvers });
 
 const app = express();
+app.use('*', cors({ origin: `http://localhost:3000` }));
 app.use('/graphql', bodyParser.json(), graphqlExpress({ schema }));
-app.use('/graphiql', graphiqlExpress({ endpointURL: '/graphql' }));
-app.listen(4000, () => {
+app.use('/graphiql', graphiqlExpress({
+  endpointURL: '/graphql',
+  subscriptionsEndpoint: `ws://localhost:4000/subscriptions`
+}));
+const ws = createServer(app);
+ws.listen(4000, () => {
   console.log('Go to http://localhost:4000/graphiql to run queries!');
+
+  new SubscriptionServer({
+    execute,
+    subscribe,
+    schema
+  }, {
+    server: ws,
+    path: '/subscriptions',
+  });
 });

backend/package.json

@@ -12,7 +12,11 @@
   "dependencies": {
     "apollo-server-express": "^1.3.2",
     "body-parser": "^1.18.2",
+    "cors": "^2.8.4",
     "express": "^4.16.2",
-    "graphql-tools": "^2.21.0"
+    "graphql-subscriptions": "^0.5.7",
+    "graphql-tools": "^2.21.0",
+    "http": "0.0.0",
+    "subscriptions-transport-ws": "^0.9.5"
   }
 }