Monday, April 16, 2018

Simple CRUD app using REST api part - 1



  • What is REST?

    • Best thing ever. makes developers life much easier.
    • REST means Representational State Transfer 
    • You can simply make a CRUD app using this.
    REST API Architecture


    • Client makes HTTP requests to the API
    • API handles Routes,Business Logic
    • Sends and retrieve data from the database.
    • This is simple, scalable and reliable.



  • We are going to make a simple REST app using Node Express framework and MongoDB.
  • First you have follow these and setup the project.
  1. First you have setup node and create a project. I have explained this in my Node.js for dummies post.
  2. Then you have to setup MonogoDB and keep it running. I have explained this in my MongoDB for dummies post
  3. You need a postman app for testing HTTP requests. Download  it from  here.
  4. And you need Robo 3T app for MongoDB GUI supporter. Thank me later for this Robo 3T.

  • Now lets get our hands dirty,


  • First we add express frame work to our project
npm install express --save

  • this --save adds the dependency or "external resources" to package.json file in the project.
Now we can start development,

  • First thing to be done is import the dependency, by requiring it on the top of the project. otherwise we cannot use express.
const express=require('express');
  • I declare it as constant, because this variable should be declared only once.
  • Then i create an instance of the app.
const app=express();

  • And now app contains all the properties functions of an express app.


{ [EventEmitter: app]
  domain: undefined,
  _events: { mount: [Function: onmount] },
  _maxListeners: undefined,
  setMaxListeners: [Function: setMaxListeners],
  getMaxListeners: [Function: getMaxListeners],
  emit: [Function: emit],
  addListener: [Function: addListener],
  on: [Function: addListener],
  prependListener: [Function: prependListener],
  once: [Function: once],
  prependOnceListener: [Function: prependOnceListener],
  removeListener: [Function: removeListener],
  removeAllListeners: [Function: removeAllListeners],
  listeners: [Function: listeners],
  listenerCount: [Function: listenerCount],
  eventNames: [Function: eventNames],
  init: [Function: init],
  defaultConfiguration: [Function: defaultConfiguration],
  lazyrouter: [Function: lazyrouter],
  handle: [Function: handle],
  use: [Function: use],
  route: [Function: route],
  engine: [Function: engine],
  param: [Function: param],
  set: [Function: set],
  path: [Function: path],
  enabled: [Function: enabled],
  disabled: [Function: disabled],
  enable: [Function: enable],
  disable: [Function: disable],
  acl: [Function],
  bind: [Function],
  checkout: [Function],
  connect: [Function],
  copy: [Function],
  delete: [Function],
  get: [Function],
  head: [Function],
  link: [Function],
  lock: [Function],
  'm-search': [Function],
  merge: [Function],
  mkactivity: [Function],
  mkcalendar: [Function],
  mkcol: [Function],
  move: [Function],
  notify: [Function],
  options: [Function],
  patch: [Function],
  post: [Function],
  propfind: [Function],
  proppatch: [Function],
  purge: [Function],
  put: [Function],
  rebind: [Function],
  report: [Function],
  search: [Function],
  subscribe: [Function],
  trace: [Function],
  unbind: [Function],
  unlink: [Function],
  unlock: [Function],
  unsubscribe: [Function],
  all: [Function: all],
  del: [Function],
  render: [Function: render],
  listen: [Function: listen],
  request: IncomingMessage { app: [Circular] },
  response: ServerResponse { app: [Circular] },
  cache: {},
  engines: {},
  settings:
   { 'x-powered-by': true,
     etag: 'weak',
     'etag fn': [Function: generateETag],
     env: 'development',
     'query parser': 'extended',
     'query parser fn': [Function: parseExtendedQueryString],
     'subdomain offset': 2,
     'trust proxy': false,
     'trust proxy fn': [Function: trustNone],
     view: [Function: View],
     views: 'F:\\Projects\\Node\\REST-app1\\views',
     'jsonp callback name': 'callback' },
  _eventsCount: 1,
  locals:
   { settings:
      { 'x-powered-by': true,
        etag: 'weak',
        'etag fn': [Function: generateETag],
        env: 'development',
        'query parser': 'extended',
        'query parser fn': [Function: parseExtendedQueryString],
        'subdomain offset': 2,
        'trust proxy': false,
        'trust proxy fn': [Function: trustNone],
        view: [Function: View],
        views: 'F:\\Projects\\Node\\REST-app1\\views',
        'jsonp callback name': 'callback' } },
  mountpath: '/' }





  • You can see it all. Don't get confused. Only for GEEKS.

  • Now we have setup our app.
  • We have to listen to incoming requests on a port.
  • But how do we listen to incoming requests.
app.listen(process.env.port||3000,function () {
console.log("listeing on port 3000");
});


  • This  code does that for us. the process.env.port||3000
  • This tell us to listen on port 3000 or port on the web server environment that the app can listen to requests.

































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