Web Technology Experts Notes

Thursday, 8 June 2017

How to Create RESTful APIs in Node Js using Express JS and MongoDB

Question: What is RESTful APIs?
Full form of REST is Representational State Transfer. It is web standards architecture used to create an API.

Question: What type of request handled by RESTful APIs?
HTTP requests

Question: How to create an API?

Create a folder with name of api in your node project, and create three folder inside this. i.e controllers, models and routes.
Create 3 empty files in each folder i.e todoListController.js, todoListModel.js and todoListRoutes.js
Now, Folder Structure will be as below:

-api
    --api/controllers/todoListController.js
    --api/models/todoListModel.js
    --api/routes/todoListRoutes.js

Add Following script in each empty file: todoListController.js

var mongoose = require('mongoose'),
        Task = mongoose.model('Tasks');

/* List all todoList*/
exports.list_all_tasks = function(req, res) {
    Task.find({}, function(err, task) {
        if (err)
            res.send(err);
        res.json(task);
    });
};


/* List all todoList*/
exports.create_a_task = function(req, res) {
    var saveData = {}
    saveData.name = req.body.name;
    saveData.status = req.body.status;
    var new_task = new Task(saveData);
    new_task.save(function(err, task) {
        if (err)
            res.send(err);
        res.json(task);
    });    
};

/* Get a todo list details*/
exports.read_a_task = function(req, res) {
    Task.findById(req.params.taskId, function(err, task) {
        if (err)
            res.send(err);
        res.json(task);
    });
};

/* UPdate a toto data*/
exports.update_a_task = function(req, res) {
    Task.findOneAndUpdate(req.params.taskId, req.body, {new : true}, function(err, task) {
        if (err)
            res.send(err);
        res.json(task);
    });
};


exports.delete_a_task = function(req, res) {
    Task.remove({
        _id: req.params.taskId
    }, function(err, task) {
        if (err)
            res.send(err);
        res.json({message: 'Task successfully deleted'});
    });
};

todoListModel.js

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var TaskSchema = new Schema({
    name: {
        type: String,
        Required: 'Kindly enter the name of the task'
    },
    Created_date: {
        type: Date,
        default: Date.now
    },
    status: {
        type: [{
                type: String,
                enum: ['pending', 'ongoing', 'completed']
            }],
        default: ['ongoing']
    }
});

module.exports = mongoose.model('Tasks', TaskSchema);

todoListRoutes.js

module.exports = function(app) {
    var todoList = require('../controllers/todoListController');


    // todoList Routes
    app.route('/tasks')
            .get(todoList.list_all_tasks)
            .post(todoList.create_a_task);


    app.route('/tasks/:taskId')
            .get(todoList.read_a_task)
            .post(todoList.update_a_task)
            .delete(todoList.delete_a_task);
};

Create a myapp.js empty file in project folder and add following script code.

var express = require('express'),
app = express(),
port = process.env.PORT || 3000,
mongoose = require('mongoose'),
Task = require('./api/models/todoListModel'),
bodyParser = require('body-parser');

mongoose.Promise = global.Promise;
mongoose.connect('mongodb://localhost/Tododb');

app.use(bodyParser.urlencoded({extended: true}));
app.use(bodyParser.json());

var routes = require('./api/routes/todoListRoutes');
routes(app);

app.listen(port);
console.log('RESTful API server started: ' + port+' PORT');

Now you need install following modules

npm install express
npm install mongoose
npm install body-parser

Now run following command, to test the APIs
```
node myapp.js
```

Question: Provide Create Task API
URL: http://localhost:3000/tasks
Method: POST
Request Data:

{
"name":"I need to go for walk",
"status":"ongoing"
}

Question: Provide List All records API
URL: http://localhost:3000/tasks
Method: POST
Response Data:

[{"_id":"5937ff6a5fc96f1c1492877f","name":"I will go for walk daily.","__v":0,"status":["ongoing"],"Created_date":"2017-06-07T13:28:10.608Z"},{"_id":"593803fb5fc96f1c14928782","name":"Get up early in the morning","__v":0,"status":["ongoing"],"Created_date":"2017-06-07T13:47:39.246Z"}]

Question: Provide Update Records
URL: http://localhost:3000/tasks/5938d8e86d3e500cd8da6a12
Method: POST
Request Data:

{  
  "name": "I goes on walk daily.", 
}

Question: Provide Get Records:
URL: http://localhost:3000/tasks/5938d8e86d3e500cd8da6a12
Method: POST
Response Data:

{"_id":"5938d8e86d3e500cd8da6a12","name":"Arun kumar Gupta","__v":0,"status":["ongoing"],"Created_date":"2017-06-08T04:56:08.156Z"}

Question: Provide Delete Records
URL: http://localhost:3000/tasks/5938d8e86d3e500cd8da6a12
Method: DELETE
Response Data:

{
  "message": "Task successfully deleted"
}

Tuesday, 6 June 2017

How to use cookies with expressJS in node.js

Question: What is cookies in NodeJS?
Cookies is a node.js module for getting and setting HTTP(S) cookies.

Question: How to install cookies?

npm install cookie-parser

Question: How to setup cookie with expressJS?

var express = require('express');
var cookieParser = require('cookie-parser');

var app = express();
app.use(cookieParser());

Question: What are the feature of cookie?

Lazy: Since cookie verification against multiple keys could be expensive, So cookies are verified lazily.
Secure: All cookies are httponly by default and cookies sent over SSL are secure by default.
Unobtrusive: Signed cookies are stored the same way as unsigned cookies, instead of in an obfuscated signing format.
Agnostic: This library is optimized for use with Keygrip, but does not require it.

Question: How to set cookies?

app.get('/set-cook', function(req, res) {
       //Set the cookie
      var c_name='cookie_name';        
      res.cookie(c_name, 'cookie value');
      
      //Send Response
      res.send('cookie value');
});

Note above wll work with expressJs only.
Question: How to get cookies?

app.get('/get-cook', function(req, res) {        
    //Get cookie name
      var cookieValue=req.cookies.cookie_name; 

      //Send Response
      res.send('Cookie name is '+cookieValue);
});

Note above wll work with expressJs only.

Question: How to delete cookies?

app.get('/delete-cook', function(req, res) {        

    //Delete the cookie
     clearCookie(cookie_name);

      //Send Response
      res.send('Cookie name is '+cookieValue);
});

Note above wll work with expressJs only.

Question: How to set expiration time for cookie?

res.cookie(name , 'value', {expire : new Date() + 600}); //10 minutes

res.cookie(name , 'value', {expire : new Date() + 3600}); //1 hour

res.cookie(name , 'value', {expire : new Date() + 18000}); //5 hour

Question: What are HTTP cookies?
HTTP cookies are small pieces of data that are sent from a website and stored in your browser. With use of cookies we maintain the login and track the user activities. Cookies are very valuable to better user experience. Following are the three main use of cookies.

Session management
Personalization
Track the user activites

Question: Why we must use Cookie-Free Domains for static contents?
Cookies are very useful in website. But while access static contents of website like CSS, image and JS then there is no use of cookie. Means while Browser is accessing the static file, Server should send the static content without use of cookie. It will improve the website performance.