Express getting started (#147)

* added code

* removed cdk code

* added code examples

* added ts files

Co-authored-by: Pratik Das <pratikd2001@gmail.com>
Co-authored-by: Tom Hombergs <tom.hombergs@gmail.com>

node/express/getting-started/README.md

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+# Related Blog Posts
+
+* [Getting Started with Express](https://reflectoring.io/getting-started-with-express/)

node/express/getting-started/app.ts

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+import express, { Request, Response, NextFunction } from 'express';
+
+const app = express();
+const port = 3000;
+
+
+interface Product {
+    name: string;
+    price: number;
+    brand: string;
+  };
+
+const getProducts = (request: Request, response: Response, next: NextFunction) => {
+    let products: Product[] = [
+      {"name":"television", "price":112.34, "brand":"samsung"},
+      {"name":"washing machine", "price": 345.34, "brand": "LG"},
+      {"name":"Macbook", "price": 3454.34, "brand": "Apple"}
+    ]
+
+    response.status(200).json(products);
+}
+app.get('/products', getProducts);
+
+app.listen(port, () => {
+    console.log(`Server listening at port ${port}.`);
+  });

node/express/getting-started/errormiddleware.js

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+// errormiddleware.js
+const errorLogger = (err, request, response, next) => {
+    console.log( `error ${err.message}`) 
+    next(err) // calling next middleware
+  }
+  
+const errorResponder = (err, request, response, next) => {
+  response.header("Content-Type", 'application/json')
+    
+  const status = err.status || 400
+  response.status(status).send(err.message)
+  }
+const invalidPathHandler = (request, response, next) => {
+  response.status(400)
+  response.send('invalid path')
+  }
+  
+module.exports = { errorLogger, errorResponder, invalidPathHandler }
+

node/express/getting-started/index.js

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+const express = require('express');
+
+const app = express();
+
+const requestLogger = (request, response, next) => {
+  console.log(request);
+  next();
+};
+
+const requireJsonContent = (request, response, next) => {
+  if (request.headers['content-type'] !== 'application/json') {
+      response.status(400).send('Server requires application/json')
+  } else {
+    next()
+  }
+}
+
+app.use(requestLogger);
+
+
+app.use((err, request, response, next) => {
+  response.status(500).send('Error!')
+})
+
+// Set the body size limit to 100 bytes
+app.use(express.json({ limit: 100 }));
+
+app.use(express.urlencoded({ extended: false }));
+
+let products = [{"name":"television", "price":112.34, "brand":"samsung"},
+{"name":"washing machine", "price": 345.34, "brand": "LG"},
+{"name":"Macbook", "price": 3454.34, "brand": "Apple"}];
+
+
+// handle get request for path /
+app.get('/', (request, response) => {
+  response.send('response for GET request');
+});
+
+// handle get request for path /products
+app.get('/products', (request, response) => {
+
+  response.json(products);
+});
+
+// handle get request for path /products
+app.get('/products/:brand', (request, response) => {
+
+  const brand = req.params.brand;
+
+  console.log("brand ${brand} " + brand);
+  
+  const productsFiltered = products.filter(product=> product.brand == brand);                  
+
+  response.json(productsFiltered);
+});
+
+// handle post request for path /products
+app.post('/products', requireJsonContent, (request, response) => {
+  const products = [];
+
+  const name = req.body.name  ;                
+
+  const brand = req.body.brand;
+
+  console.log(name + " " + brand);
+  
+  products.push({name: req.body.name, brand: req.body.brand, price: req.body.price});               
+ 
+  const productCreationResponse = {productID: "12345", result: "success"};
+  response.json(productCreationResponse);
+});
+
+app.set('view engine', 'pug')
+app.set('views', './views')
+app.get('/home',  (request, response) => {
+  response.render("home", { title: "Home", message: "My home page" , sysdate: new Date().toLocaleString()})
+})
+
+
+// handle get request with 3 middleware functions
+app.get('/users', (request, response, next) => {
+  console.log("Stage 1 processing ");
+  next()
+},
+(request, response, next) => {
+  console.log("Stage 2 processing ");
+  next();
+},
+(request, response) => {
+  response.send('response for GET request');
+});
+
+
+app.get('/products/error', (request, response) => {
+  throw new Error("processing error!")
+});
+// start the server
+const port = 3000
+app.listen(3000, 
+   () => console.log(`Server listening on port ${port}.`));
+

node/express/getting-started/middleware.js

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+// middleware.js
+
+const requestLogger = (request, response, next) => {
+    console.log(request);
+    next();
+};
+  
+const requireJsonContent = (request, response, next) => {
+    if (request.headers['content-type'] !== 'application/json') {
+        response.status(400).send('Server requires application/json')
+    } else {
+      next()
+    }
+}
+
+module.exports = { requestLogger, requireJsonContent}

node/express/getting-started/package.json

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+{
+  "name": "storefront",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "serve": "nodemon app.ts"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "express": "^4.17.2",
+    "pug": "^3.0.2"
+  },
+  "devDependencies": {
+    "@types/express": "^4.17.13",
+    "@types/node": "^17.0.17",
+    "nodemon": "^2.0.15",
+    "ts-node": "^10.5.0",
+    "typescript": "^4.5.5"
+  }
+}

node/express/getting-started/routes.js

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+// routes.js
+const express = require('express')
+const { requireJsonContent } = require('./middleware')
+
+const router = express.Router()
+
+// Set the body size limit to 100 bytes
+router.use(express.json({ limit: 100 }))
+
+let  products = [{"name":"television", "price":112.34, "brand":"samsung"},
+{"name":"washing machine", "price": 345.34, "brand": "LG"},
+{"name":"Macbook", "price": 3454.34, "brand": "Apple"}];
+
+// handle get request for path /products
+router.get('/products', (request, response) => {
+  console.log(products)
+  response.json(products)
+});
+
+// handle get request for path /products
+router.get('/products/:brand', (request, response) => {
+
+  const brand = request.params.brand;
+
+  console.log(`brand ${brand} `);
+  
+  const productsFiltered = products.filter(product=> product.brand == brand);                  
+
+  response.json(productsFiltered);
+});
+
+
+// handle post request for path /products
+router.post('/products', requireJsonContent,(request, response) => {
+
+  const name = request.body.name  ;                
+
+  const brand = request.body.brand;
+
+  console.log(name + " " + brand);
+  
+  products.push({name: request.body.name, brand: request.body.brand, price: request.body.price});               
+ 
+  const productCreationResponse = {productID: "12345", result: "success"};
+  response.json(productCreationResponse);
+});
+
+// handle put request for path /products
+router.put('/products', (request, response) => {
+
+  const name = request.body.name  ;                
+
+  const brand = request.body.brand;
+
+  console.log(name + " " + brand);
+  
+  products.push({name: request.body.name, brand: request.body.brand, price: request.body.price});               
+ 
+  const productCreationResponse = {productID: "12345", result: "success"};
+  response.json(productCreationResponse);
+})
+
+router.get('/home',  (request, response) => {
+  console.log("rendering...")
+  response.render("home", { title: "Home", message: "My home page" , sysdate: new Date().toLocaleString()})
+})
+
+router.get('/productswitherror', (request, response) => {
+  let err = new Error("processing error ")
+  err.statusCode = 400
+  throw err
+});
+
+
+module.exports = router

node/express/getting-started/server.js

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+// server.js
+const express = require('express')
+const routes = require('./routes')
+
+const { requestLogger } = require('./middleware')
+const { errorLogger, errorResponder, invalidPathHandler } = require('./errormiddleware')
+
+
+const app = express()
+const PORT = process.env.PORT || 3000
+
+app.use(requestLogger)
+app.use(routes)
+
+app.use(errorLogger)
+app.use(errorResponder)
+app.use(invalidPathHandler)
+
+app.set('view engine', 'pug')
+app.set('views', './views')
+
+
+app.listen(PORT, () => {
+console.log(`Server listening at http://localhost:${PORT}`)
+})

node/express/getting-started/tsconfig.json

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+{
+    "compilerOptions": {
+      "module": "commonjs",
+      "target": "es6",
+      "rootDir": "./",
+      "esModuleInterop": true
+    }
+  }

node/express/getting-started/views/home.pug

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+html
+  head
+    title= title
+  body
+    h1= message
+    div
+      p Generated by express at 
+        span= sysdate