Add example for request id logging

examples/express-ts/README.md

@@ -13,12 +13,21 @@ $ yarn start
 ```
 Now you can test it through `curl`. Trigger concurrent requests with different ids that are a part of request context.
 ```
-$ curl localhost:3000 -H X-Id:1 && curl localhost:3000 -H X-Id:2 && curl localhost:3000 -H X-Id:3
+$ curl 'http://localhost:3000?a=20&b=30' && curl 'http://localhost:3000?a=10&b=50' && curl 'http://localhost:3000?a=50&b=100'
 ```
 **Output**
 ```
-X-Id received in the middleware: 1
-X-Id received in the middleware: 2
-X-Id received in the middleware: 3
+[ DEBUG ] [ 445ef6fb ] Received a: 20
+[ DEBUG ] [ 445ef6fb ] Received b: 30
+[ INFO ] [ 445ef6fb ] Simulating Delay
+[ DEBUG ] [ 445ef6fb ] Calculated sum: 50
+[ DEBUG ] [ b4c27a00 ] Received a: 10
+[ DEBUG ] [ b4c27a00 ] Received b: 50
+[ INFO ] [ b4c27a00 ] Simulating Delay
+[ DEBUG ] [ b4c27a00 ] Calculated sum: 60
+[ DEBUG ] [ a24d4281 ] Received a: 50
+[ DEBUG ] [ a24d4281 ] Received b: 100
+[ INFO ] [ a24d4281 ] Simulating Delay
+[ DEBUG ] [ a24d4281 ] Calculated sum: 150
 
 ```

examples/express-ts/src/index.ts

@@ -3,23 +3,23 @@ import { Request, Response } from 'express';
 
 import * as store from '@leapfrogtechnology/async-store';
 
-import * as service from './service';
-import { requestContext, otherMiddleware } from './middlewares';
+import * as logger from './logger';
+import { requestParams, add } from './middlewares';
 
 const app = express();
 const port = 3000;
 
 app.use(store.initializeMiddleware());
-app.use(requestContext());
+app.use(requestParams());
 
-app.get('/', otherMiddleware, async (req: Request, res: Response) => {
-  await service.doSomething();
+app.get('/', add(), async (req: Request, res: Response) => {
+  const a = store.get('a');
+  const b = store.get('b');
+  const sum = store.get('sum');
 
-  const requestId = store.get('x-id');
-
-  res.send(`Response to request: ${requestId}\n`);
+  res.send(`Sum of ${a}, ${b}: ${sum}\n`);
 });
 
 app.listen(port, () => {
-  process.stdout.write(`Express server listening on port ${port}!\n`);
+  logger.info(`Express server listening on port ${port}!\n`);
 });

examples/express-ts/src/logger.ts

@@ -0,0 +1,32 @@
+import * as store from '@leapfrogtechnology/async-store';
+
+/**
+ * Get unique request id from store or return empty string
+ *
+ * @returns {string}
+ */
+function getRequestId() {
+  return (store.getId() || '').substring(0, 8);
+}
+
+/**
+ * A example service to log info with unique request id
+ *
+ * @param {string} infoText
+ */
+export function info(infoText: string) {
+  const requestId = getRequestId();
+
+  process.stdout.write(`[ INFO ] ${requestId ? `[ ${requestId} ]` : ''} ${infoText}\n`);
+}
+
+/**
+ * A example service to log debug with unique request id
+ *
+ * @param {string} debugText
+ */
+export function debug(debugText: string) {
+  const requestId = getRequestId();
+
+  process.stdout.write(`[ DEBUG ] ${requestId ? `[ ${requestId} ]` : ''} ${debugText}\n`);
+}

examples/express-ts/src/middlewares.ts

@@ -1,6 +1,50 @@
 import * as store from '@leapfrogtechnology/async-store';
 import { Request, Response, NextFunction } from 'express';
 
+import * as logger from './logger';
+
+/**
+ * Middleware to set query params `a` and `b` on async-store
+ *
+ * @returns {(req, res, next) => void}
+ */
+export function requestParams() {
+  return async (req: Request, res: Response, next: NextFunction) => {
+    const a = req.query.a;
+    const b = req.query.b;
+
+    store.set({
+      a: parseFloat(a) || 0,
+      b: parseFloat(b) || 0
+    });
+
+    logger.debug(`Received a: ${a}`);
+    logger.debug(`Received b: ${b}`);
+
+    next();
+  };
+}
+
+/**
+ * Middleware to add the parameters `a` and `b` and set `sum` on the async store.
+ *
+ * @returns {(req, res, next) => void}
+ */
+export function add() {
+  return (req: Request, res: Response, next: NextFunction) => {
+    logger.info('Simulating Delay');
+    const a = store.get('a');
+    const b = store.get('b');
+
+    const sum = a + b;
+
+    store.set({ sum });
+    logger.debug(`Calculated sum: ${sum}`);
+
+    next();
+  };
+}
+
 /**
  * Middleware to set the request context `x-id` on the async store.
  *
@@ -22,7 +66,7 @@ export function requestContext() {
 export function otherMiddleware(req: Request, res: Response, next: NextFunction) {
   const requestId = store.get('x-id');
 
-  process.stdout.write(`X-Id received in the middleware: ${requestId}\n`);
+  logger.info(`X-Id received in the middleware: ${requestId}\n`);
 
   next();
 }

examples/express-ts/src/service.ts

@@ -1,4 +1,5 @@
 import * as store from '@leapfrogtechnology/async-store';
+import * as logger from './logger';
 
 /**
  * An example function making use of the request context set in the store.
@@ -8,7 +9,9 @@ import * as store from '@leapfrogtechnology/async-store';
 export async function doSomething() {
   // Do something with the request.
 
-  await Promise.all([() => logRequestContext()]);
+  setTimeout(() => {
+    logRequestContext();
+  }, 2000);
 }
 
 /**
@@ -19,5 +22,5 @@ export async function doSomething() {
 async function logRequestContext() {
   const requestId = store.get('x-id');
 
-  process.stdout.write(`Request context: ${requestId}\n`);
+  logger.info(`Request context: ${requestId}\n`);
 }