From 5af650d7bcd3eb0c5721b10a0bd22e71d5b5d7d2 Mon Sep 17 00:00:00 2001
From: Varayut Lerdkanlayanawat <l.varayut@gmail.com>
Date: Thu, 17 Mar 2016 23:05:16 +0700
Subject: [PATCH] Automatically restart GraphQL server and Relay server when
 files are changed

---
 server/index.js                 | 48 ++++++++++++++++++++++++---------
 server/utils/requireUncached.js |  4 +++
 server/utils/updateSchema.js    |  6 +++--
 3 files changed, 43 insertions(+), 15 deletions(-)
 create mode 100644 server/utils/requireUncached.js

diff --git a/server/index.js b/server/index.js
index 6fc9578..8ba450a 100644
--- a/server/index.js
+++ b/server/index.js
@@ -4,23 +4,28 @@ import express from 'express';
 import graphQLHTTP from 'express-graphql';
 import WebpackDevServer from 'webpack-dev-server';
 import gaze from 'gaze';
+import requireUncached from './utils/requireUncached';
 import webpackConfig from '../webpack.config';
 import config from './config/environment';
 import schema from './data/schema';
 import updateSchema from './utils/updateSchema';
 
-if (config.env === 'development') {
-  // Launch GraphQL
+let graphQLServer;
+let relayServer;
+
+function startGraphQLServer(schema) {
   const graphql = express();
   graphql.use('/', graphQLHTTP({
     graphiql: true,
     pretty: true,
     schema
   }));
-  graphql.listen(config.graphql.port, () => console.log(`GraphQL is listening on port ${config.graphql.port}`));
+  graphQLServer = graphql.listen(config.graphql.port, () => console.log(`GraphQL is listening on port ${config.graphql.port}`));
+}
 
+function startRelayServer() {
   // Launch Relay by using webpack.config.js
-  const app = new WebpackDevServer(webpack(webpackConfig), {
+  relayServer = new WebpackDevServer(webpack(webpackConfig), {
     contentBase: '/build/',
     proxy: {
       '/graphql': `http://localhost:${config.graphql.port}`
@@ -33,21 +38,38 @@ if (config.env === 'development') {
   });
 
   // Serve static resources
-  app.use('/', express.static(path.join(__dirname, '../build')));
-  app.listen(config.port, () => console.log(`Relay is listening on port ${config.port}`));
+  relayServer.use('/', express.static(path.join(__dirname, '../build')));
+  relayServer.listen(config.port, () => console.log(`Relay is listening on port ${config.port}`));
+}
+
+if (config.env === 'development') {
+  // Start GraphQL and Relay servers
+  startGraphQLServer(schema);
+  startRelayServer();
 
   // Watch JavaScript files in the data folder for changes, and update schema.json and schema.graphql
   gaze(path.join(__dirname, 'data/*.js'), (err, watcher) => {
     if (err) console.error('Error: Watching files in data folder');
-    watcher.on('all', () => {
-      updateSchema();
+    watcher.on('all', async() => {
+      try {
+        // Close the GraphQL server, update the schema.json and schema.graphql, and start the server again
+        graphQLServer.close();
+        await updateSchema();
+        const newSchema = requireUncached(path.join(__dirname, './data/schema')).default;
+        startGraphQLServer(newSchema);
+
+        // Close the Relay server, and start it again
+        relayServer.listeningApp.close();
+        startRelayServer();
+      } catch (e) {
+        console.error(e.stack);
+      }
     });
   });
 } else if (config.env === 'production') {
   // Launch Relay by creating a normal express server
-  const app = express();
-  app.use('/', express.static(path.join(__dirname, '../build')));
-  app.use('/graphql', graphQLHTTP({ schema }));
-  app.listen(config.port, () => console.log(`App is listening on port ${config.port}`));
+  relayServer = express();
+  relayServer.use('/', express.static(path.join(__dirname, '../build')));
+  relayServer.use('/graphql', graphQLHTTP({ schema }));
+  relayServer.listen(config.port, () => console.log(`App is listening on port ${config.port}`));
 }
-
diff --git a/server/utils/requireUncached.js b/server/utils/requireUncached.js
new file mode 100644
index 0000000..9e6836b
--- /dev/null
+++ b/server/utils/requireUncached.js
@@ -0,0 +1,4 @@
+export default (module) => {
+  delete require.cache[require.resolve(module)];
+  return require(module);
+};
diff --git a/server/utils/updateSchema.js b/server/utils/updateSchema.js
index de3d645..cd787bb 100644
--- a/server/utils/updateSchema.js
+++ b/server/utils/updateSchema.js
@@ -1,15 +1,17 @@
 import path from 'path';
 import fs from 'fs';
-import schema from '../data/schema';
 import {graphql} from 'graphql';
 import {introspectionQuery, printSchema} from 'graphql/utilities';
+import requireUncached from '../utils/requireUncached';
 
+const schemaFile = path.join(__dirname, '../data/schema.js');
 const jsonFile = path.join(__dirname, '../data/schema.json');
 const graphQLFile = path.join(__dirname, '../data/schema.graphql');
 
 async function updateSchema() {
   try {
-    let json = await graphql(schema, introspectionQuery);
+    const schema = requireUncached(schemaFile).default;
+    const json = await graphql(schema, introspectionQuery);
     fs.writeFileSync(jsonFile, JSON.stringify(json, null, 2));
     fs.writeFileSync(graphQLFile, printSchema(schema));
     console.log('Schema has been regenerated');