Angular Cheat Sheet

February 4, 2021

5:15 am

my-app\src\app\interceptor\httpconfig.interceptor.ts

import { Injectable } from '@angular/core';
import {
    HttpInterceptor,
    HttpRequest,
    HttpResponse,
    HttpHandler,
    HttpEvent,
    HttpErrorResponse
} from '@angular/common/http';

import { Observable, throwError } from 'rxjs';
import { map, catchError } from 'rxjs/operators';

@Injectable()
export class HttpConfigInterceptor implements HttpInterceptor {
    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        const token: any = localStorage.getItem('token');
        // const token: string = `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1X25hbWUiOiJhZG1pbiIsInB3ZCI6IkBkbWluIiwiaWF0IjoxNjEyNjM2OTc5fQ.ehlxu7z_1HSW4bPK902nLOAZOpHtutfkJ43lCxQnL68`;
        if (token) {
            request = request.clone({ headers: request.headers.set('Authorization', 'Bearer ' + token) });
        }

        if (!request.headers.has('Content-Type')) {
            request = request.clone({ headers: request.headers.set('Content-Type', 'application/json') });
        }

        request = request.clone({ headers: request.headers.set('Accept', 'application/json') });

        return next.handle(request).pipe(
            map((event: HttpEvent<any>) => {
                if (event instanceof HttpResponse) {
                    console.log('event--->>>', event);
                }
                return event;
            }));
    }
}

app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { RouterModule } from '@angular/router';

import {FormsModule, ReactiveFormsModule} from '@angular/forms';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http'
import { HttpConfigInterceptor } from './interceptor/httpconfig.interceptor';


@NgModule({
  declarations: [
    AppComponent,
  ],
  imports: [
    HttpClientModule
  ],
  providers: [
    { provide: HTTP_INTERCEPTORS, useClass: HttpConfigInterceptor, multi: true }
  ],
  bootstrap: [AppComponent]

})
export class AppModule { }

Mongoose Express CRUD

by admin

February 3, 2021

6:51 pm

Leave a comment on Mongoose Express CRUD

Javascript

const mongoose = require("mongoose");
const conn_str = "mongodb://localhost:27017/tcet"
mongoose.connect(conn_str, { useNewUrlParser: true , useUnifiedTopology: true})
	.then( () => console.log("Connected successfully...") )
	.catch( (err) => console.log(err) );

const userSchema = new mongoose.Schema({
	name: String,
	age: Number,
	city: String,
	state: String
});

const user = new mongoose.model("user", userSchema);

/** Express Mongoose Integration **/

const express = require("express");
const app = express();

app.route("/user")
.get(async (req, res) => {
	let data = await user.find();
	res.send(data);
})
.post(async (req, res) => {
	req_data = req.query;
	let obj = new user(req.query)
	let result = await obj.save();
	res.send(result);
})
.put(async (req, res) => {
	req_data = req.query;
	let result = await user.updateOne({_id: req.query.id}, {$set : {city: req.query.city}})
	res.send(result);
})
.delete(async (req, res) => {
	let result = await user.deleteOne({_id: req.query.id})
	res.send(result);
})

app.listen(8080, () => {
	console.log("listening 8080...");
});

Connect to MongoDB Atlas Cluster

Whitelist your ip / or allow from all 0.0.0.0/0

Get Your Current IP Address from google > what is my ip

Atlas > Security > Network Access > ADD IP ADDRESS

First get the connection string or URI from Atlas

Atlas > Deployment > Databases > Connect > Connect your application > Driver Node.js > Version 2.2.12 or later

const port = 8080;
const mongoose = require("mongoose");
const uri ="get_uri_from_atlas"
mongoose.connect(uri, { useNewUrlParser: true , useUnifiedTopology: true})
	.then( () => console.log("Connected successfully...") )
	.catch( (err) => console.log(err) );

const userSchema = new mongoose.Schema({
	name: String,
	age: Number,
	city: String
});

const user = new mongoose.model("users", userSchema);

/** Express Mongoose Integration **/

const express = require("express");
const app = express();

app.route("/user")
.get(async (req, res) => {
	let data = await user.find();
	res.send(data);
})
.post(async (req, res) => {
	req_data = req.query;
	let obj = new user(req.query)
	let result = await obj.save();
	res.send(result);
})
.put(async (req, res) => {
	req_data = req.query;
	let result = await user.updateOne({_id: req.query.id}, {$set : {city: req.query.city}})
	res.send(result);
})
.delete(async (req, res) => {
	let result = await user.deleteOne({_id: req.query.id})
	res.send(result);
})

app.listen(process.env.PORT || port, () => {
	console.log("listening 8080...");
});

NODE CUSTOM MODULE

index.js

var mymath = require("./mymodule")

console.log(mymath.add(5,6));
console.log(mymath.sub(5,6));
console.log(mymath.mul(5,6));
console.log(mymath.div(5,6));
console.log(mymath.mod(5,6));

cobj = new mymath.MyCircle(5);
cobj.area();

mymodule.js

exports.add = (x, y) => x + y;
exports.sub = (x, y) => x – y;
exports.mul = (x, y) => x * y;
exports.div = (x, y) => x / y;
exports.mod = (x, y) => x % y;

exports.MyCircle = class {

constructor(r) {
    this.radius = r;
    console.log("Hello I am My Circle Constructor...");
}

area() {
    let area = Math.PI * this.radius * this.radius;
    console.log(`Area: ${area.toFixed(2)}`);
}
}

NODE http MODULE

index.js

var http = require(“http”)

http.createServer((req, res) => {
// res.writeHead(‘Content-Type’, ‘text/plain’);
// res.writeHead(‘Content-Type’, ‘application/json’);
res.writeHead(200, {‘Content-Type’ : ‘text/html’});
res.write("this is line 1….");

console.log(req.url);

if(req.url == "/") {
    res.write("Home req hit</br>")
} else 

if(req.url == "/teacher") {
    res.write("Teacher req hit</br>")
} else 

if(req.url == "/student") {
    res.write("Student req hit</br>")
} else 

{
    res.end("Page Not Found....");
}

res.end("hello world....");
}).listen(8989, () => {
console.log("listening at port 8989…")
});

EXPRESS ROUTING

index.js

var express = require("express");
var app = express();

app.get("/", (req, res) => {
  res.send("Home Page");
});

app.get("/student", (req, res) => {
  data = { result: "Student GET Request" };
  res.send(data);
});

app.post("/student", (req, res) => {
  data = { result: "Student post Request" };
  res.send(data);
});

app.put("/student", (req, res) => {
  data = { result: "Student put Request" };
  res.send(data);
});

app.delete("/student", (req, res) => {
  data = { result: "Student delete Request" };
  res.send(data);
});

app
  .route("/teacher")
  .get((req, res) => {
    data = { result: "Teacher get Request" };
    res.send(data);
  })
  .post((req, res) => {
    data = { result: "Teacher post Request" };
    res.send(data);
  })
  .put((req, res) => {
    data = { result: "Teacher put Request" };
    res.send(data);
  })
  .delete((req, res) => {
    data = { result: "Teacher delete Request" };
    res.send(data);
  });


app.listen(8989, () => {
  console.log("Listening at port 8989");
});

RUN COMMAND

#if file is index.js then you can simply run using . instead of filename
node .
node app.js

#install nodemon
npm i nodemon
OR
npm i -g nodemon

nodemon .
nodemon app.js

OR
 
./node_modules/nodemon/bin/nodemon.js .
./node_modules/nodemon/bin/nodemon.js app.js

EXPRESS MODULAR ROUTING

index.js

var express = require("express");
var app = express();
var home = require("./home");
var student = require("./student");
var teacher = require("./teacher");

app.use("/", home);
app.use("/student", student);
app.use("/teacher", teacher);

app.use(function (req, res, next) {
  res.status(404);
  res.send("404: File Not Found");
});

app.listen(8989, () => {
  console.log("Listening at port 8989");
});

student.js

const express = require("express");
const router = express.Router();

router
  .route("/")
  .get((req, res) => {
    res.send("student listing");
  })

  .post((req, res) => {
    res.send("student post");
  })

  .put((req, res) => {
    res.send("student put");
  })

  .delete((req, res) => {
    res.send("student delete");
  });

module.exports = router;

teacher.js

const express = require("express");
const router = express.Router();
router
  .route("/")
  .get((req, res) => {
    res.send("teachers listing");
  })
  .post((req, res) => {
    res.send("teachers post");
  })
  .put((req, res) => {
    res.send("teachers put");
  })
  .delete((req, res) => {
    res.send("teachers delete");
  });

module.exports = router;

EXPRESS READ DATA

index.js

const express = require("express");
const app = express();
app.use(express.json());

app
  .route("/")
  .get((req, res) => {
    data = req.query;
    res.send(data);
  })
  .post((req, res) => {
    data = req.body;
    res.send(data);
  })
  .put((req, res) => {
    data = req.body;
    res.send(data);
  });


app.listen(8989, () => {
  console.log("Listening at port 8989");
});

Assignment: WA Web Service to read number from user and return square and cube of that number. Return data in JSON format.

Fetch Api

<table border=1>
	<thead>
		<th>Id</th>
		<th>Name</th>
		<th>Email</th>
		<th>Aavatar</th>
	</thead>
	<tbody id="records">
		<tr>
			<td>sample </td>
			<td>sample</td>
			<td>sample</td>
			<td>sample</td>
		</tr>
	</tbody>

</table>
<img id="image" />
<script>
	url = "https://reqres.in/api/users?page=1";

	fetch(url)
	.then(res => res.json())
	.then(result => {
		console.table(result.data);
		console.log(result.data[0]['avatar'])
		document.getElementById("image").src = result.data[0]['avatar'];
		records = result.data;
		output = '';
		for(i = 0;i<records.length; i++){
			output += `<tr>`
			output += `<td>${records[i]['id']} </td>`
			output += `<td>${records[i]['first_name']} ${records[i]['last_name']}</td>`
			output += `<td>${records[i]['email']}</td>`
			output += `<td><img id="image" src="${records[i]['avatar']}" /></td>`
			output += `</tr>`
			console.log(records[i]['id'])
		}
	document.getElementById("records").innerHTML = output;
	
	})
	
</script>

Express File Upload

//get directory name
console.log(`Project Path: ${__dirname}`);

const express = require("express");
const fileUpload = require("express-fileupload");
const app = express();

//options / middleware
app.use(fileUpload());

app.post("/file_upload", (req, res) => {
	
	console.log(req.body);
	console.log(req.files);
	
	let file_to_upload = req.files.file_to_upload;
	
	//file_to_upload.mv(path,callbackfun);
	const upload_path = __dirname + '/uploads/' + file_to_upload.name;
	//file_to_upload.mv(upload_path);
	
	file_to_upload.mv(upload_path, (err) => {
		if(err) {
			res.status(500)
			res.send(err);
		}
		
		res.status(200)
		res.send("File Upload successfully...")
	})
	
});

app.listen(8989, () => {
	console.log("Listening at port 8989");
})

json webtoken

var jwt = require('jsonwebtoken');
var express = require("express");
var app = express();

username = "admin";
password = "@dmin";

app.use(express.json());

var cors = require('cors')
app.use(cors())

function errorHandler(req, res, next) {
    if (!req.headers.authorization) return res.status(401).send({message:"No token provided"});

    const token = req.headers.authorization.replace("Bearer ","");

    jwt.verify(token, 'shhhhh', function(err) {
        if (err){
            res.status(401).send({message: "unauthorized user"});
        } 
        res.send("jwt token is correct");
    });

    return res.status(500).json({ message: err.message });
}


app.route('/login')
.post((req, res)=>{
    if (username==req.body.username && password == req.body.password){
        var token = jwt.sign({ u_name: username}, 'shhhhh');
        res.send(token);
    }else{
        res.send("wrong creditionals");
    }
    
})

app.use(errorHandler)

app.route('/dashboard')
.get((req,res)=>{
    res.send("dashboard");
})

app.route('/employees')
.get((req,res)=>{
    res.send("emloypee page");
})

app.listen(8080,()=>{
    console.log("listening at 8080")
});

atlas.js

const conn_str = "mongodb+srv://<username>:<password>@clusterurl_obtained_from_mongodbatlas/<databasename>?retryWrites=true&w=majority";
//please replace username password and database name 
const mongoose = require("mongoose");

mongoose.connect(conn_str)
.then(() => console.log("Connected successfully..."))
.catch( (error) => console.log(error) );


const express = require("express");
const app = express();
app.use(express.json());

const empSchema = new mongoose.Schema({});
const emp = new mongoose.model("emps", empSchema);


var cors = require('cors')
app.use(cors())


app.get("/employees", async (req, res) => {
    // var data = [{name: "hari", salary: 25000}, {name: "sameer", salary: 23000}]
    let data = await emp.find();
    res.send(data)
})

app.listen(8989, () => {
	console.log("listening 8989...");
});

index.js

<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-T3c6CoIi6uLrA9TneNEoa7RxnatzjcDSCmG1MXxSR1GAsXEV/Dwwykc2MPK8M2HN" crossorigin="anonymous">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-C6RzsynM9kWDrMNeT87bh95OGNyZPhcTNXj1NW7RuBCsyN/o0jlpcV8Qyq46cDfL" crossorigin="anonymous"></script>

<table class="table table-striped">
    <thead>
        <tr>
            <th>Name</th>
            <th>City</th>
            <th>Phone No.</th>
            <th>Salary</th>
            <th>Action</th>
        </tr>
    </thead>
    <tbody id="records"></tbody>
</table>


<script>

url = "http://localhost:8989/employees"

fetch(url)
.then(res => res.json())
.then(res => {
    console.log(res)
    console.table(res)

    output = ''

    for(let i = 0; i < res.length; i++) {

        output += `<tr>
            <td>${res[i]['name']}</td>
            <td>${res[i]['address']}</td>
            <td>${res[i]['contact_number']}</td>
            <td>${res[i]['salary']}</td>
            <td><button class="btn btn-danger">Delete</button></td>
            </tr>`
    }

    document.getElementById("records").innerHTML = output
})

</script>

COMPARISON OPERATORS

in operator

db.students.find({_id: {$in: [2,3]}});

not equal operator

db.students.find({_id: {$ne: 2}});

equal operator

db.students.find({_id: {$eq: 2}});

less than $lt

less than equal $lte

greather than $gt

greater than equal $gte

LOGICAL OPERATORS

$and operator

db.students.find({$and : [{_id : {$gt:1}}, {_id: {$lt: 4}}]})

$or operator

db.students.find({$or : [{name : "bagde"}, {name: "shailesh"}]})

like case insensitive

db.students.find({name: /h/i})

exact match

db.students.find({name: /^BagDe$/i})

UPDATE

db.students.updateOne({_id: 1}, {$set : {age: 23}});
db.students.updateMany({age : {$exists: false}}, { $set : {age : 25}})

db.students.updateMany({}, {$set: {address: {city: "Mumbai", state: "MH"}}})
db.students.updateOne({_id: 4}, { $set : {address : {city: "Nagpur"}}});

Unset/Delete Fields

db.students.updateMany({}, {$unset : {city: ""}});

search within sub document

db.students.find({"address.city" : "Nagpur"}).pretty();

Delete Records

db.students.deleteOne({ $or : [{ age : {$lt : 25}}, {name : "sheldon"}] })

DISTINCT

db.students.distinct(“city”)

ORDER BY

db.students.find().sort({name: -1})

LIMIT

db.students.find().limit(10)
db.students.find().skip(5).limit(10)

Aggregation

Aggregate on all documents
db.emps.aggregate([{$group: {
	_id : null,
	total : {$sum : "$salary"},
	average : {$avg: "$salary"},
	min : {$min: "$salary"},
	max : {$max: "$salary"},
	count : {$sum: 1}	
}}]).pretty()


Aggregate on group by address
db.emps.aggregate([{$group: {
	_id : { address: "$address" },
	total : {$sum : "$salary"},
	average : {$avg: "$salary"},
	min : {$min: "$salary"},
	max : {$max: "$salary"},
	count : {$sum: 1}	
}}]).pretty()

ForEach Map

db.emps.find().forEach(x => { print(x.name) })

db.emps.find({salary: { $exists: -1 } }, {"salary": 1, _id: 0}).map(x => x.salary * 0.10)

MongoDB Assignment for Practice

var docs = [
{"name":"neha","contact_number":"9833910534","address":"mumbai","salary":30000,"employee_id":98821,"role":"manager"},
{"name":"mina","contact_number":"9833910535","address":"thane","salary":32000,"employee_id":98823,"role":"sales"},
{"name":"pankaj","contact_number":"9833910536","address":"bhopal","salary":40000,"employee_id":98824,"role":"hr"},
{"name":"mareena","contact_number":"9833910537","address":"meerut","salary":45000,"employee_id":98825,"role":"support"},
{"name":"pooja","contact_number":"9833910538","address":"delhi","salary":50000,"employee_id":98826,"role":"developer"},
{"name":"namita","contact_number":"9833910539","address":"surat","salary":52000,"employee_id":98820,"role":"sales"},
{"name":"sneha","contact_number":"9833910510","address":"baroda","salary":55000,"employee_id":98827,"role":"support"},
{"name":"anjali","contact_number":"9833910511","address":"ahmedabad","salary":60000,"employee_id":98828,"role":"tester"},
{"name":"harsha","contact_number":"9833910512","address":"mumbai","salary":20000,"employee_id":98829,"role":"operations"},
{"name":"varun","contact_number":"9833910512","address":"mehsana","salary":56000,"employee_id":98831,"role":"tester"},
{"name":"preeti","contact_number":"9833910513","address":"noida","salary":87000,"employee_id":98832,"role":"developer"},
{"name":"madhu","contact_number":"9833910525","address":"bangalore","salary":22000,"employee_id":98833,"role":"sales"}
];

db.createCollection("emps");
db.emps.insertMany(docs);
db.emps.find();

var docs = [{“name”:”neha”,”contact_number”:”9833910534″,”address”:”mumbai”,”salary”:30000,”employee_id”:98821,”role”:”manager”},{“name”:”mina”,”contact_number”:”9833910535″,”address”:”thane”,”salary”:32000,”employee_id”:98823,”role”:”sales”},{“name”:”pankaj”,”contact_number”:”9833910536″,”address”:”bhopal”,”salary”:40000,”employee_id”:98824,”role”:”hr”},{“name”:”mareena”,”contact_number”:”9833910537″,”address”:”meerut”,”salary”:45000,”employee_id”:98825,”role”:”support”},{“name”:”pooja”,”contact_number”:”9833910538″,”address”:”delhi”,”salary”:50000,”employee_id”:98826,”role”:”developer”},{“name”:”namita”,”contact_number”:”9833910539″,”address”:”surat”,”salary”:52000,”employee_id”:98820,”role”:”sales”},{“name”:”sneha”,”contact_number”:”9833910510″,”address”:”baroda”,”salary”:55000,”employee_id”:98827,”role”:”support”},{“name”:”anjali”,”contact_number”:”9833910511″,”address”:”ahmedabad”,”salary”:60000,”employee_id”:98828,”role”:”tester”},{“name”:”harsha”,”contact_number”:”9833910512″,”address”:”mumbai”,”salary”:20000,”employee_id”:98829,”role”:”operations”},{“name”:”varun”,”contact_number”:”9833910512″,”address”:”mehsana”,”salary”:56000,”employee_id”:98831,”role”:”tester”},{“name”:”preeti”,”contact_number”:”9833910513″,”address”:”noida”,”salary”:87000,”employee_id”:98832,”role”:”developer”},{“name”:”madhu”,”contact_number”:”9833910525″,”address”:”bangalore”,”salary”:22000,”employee_id”:98833,”role”:”sales”}];

show employees in descending order – salary
show all employees from Mumbai
show all employees having salary more 50000
show sum of salary from emps collection
show all distinct address
show names of employees having max salary
show employees having 2nd highest salary
count employees from mumbai only
show all female employees
show all male employees

TCET Session Data

by admin

February 1, 2021

4:45 am

2 Comments on TCET Session Data

C Programming

day 2:
javascript: addeventlisterner, fetchapi, validation
mongodb: crud on terminal
nodejs: core, custom module, http module
expressjs: routeing with get,post, put, delete methods
routing with route methods
read query params using res.query
read form data using res.body parser
read raw json using res.body parser
mongodb crud using nodejs (mongoose)

Day 1: JavaScript
Introduction
console.log()
console.error()
console.warning()
alert()
confirm()

variables, datatypes and scope
var x | let x | x

concatenation
template literals hello ${name}

Conditional Statement if..else

Loops for

String and String methods

Array and Array methods

Math methods

Functions

callback function

lambda expression/fatarrow function

Classes and Objects

Array of Objects

~~Inheritance~~

~~Interface~~

JSON

Array of JSON

AJAX using fetch API and json-placeholder dummy API

UI
read data from input box
put data in input box
put data in html

addEventListener

events (onclick, onkeyup, onkeydown, onkeypress, onfocus, onchange, onblur)

JavaScript Validation

Load data in table from API (Web Service: json-placeholder) using AJAX call (fetch API)

=====================================================================

Month: February 2021

PWA cheat sheet

web socket chat app

Angular Cheat Sheet

my-app\src\app\interceptor\httpconfig.interceptor.ts

Mongoose Express CRUD

mongoose cheat sheet

NodeJS Cheat Sheet

NODE CUSTOM MODULE

index.js

mymodule.js

NODE http MODULE

index.js

EXPRESS ROUTING

index.js

RUN COMMAND

EXPRESS MODULAR ROUTING

index.js

student.js

teacher.js

EXPRESS READ DATA

index.js

Fetch Api

Express File Upload

atlas.js

index.js

MongoDB Cheat Sheet

COMPARISON OPERATORS

LOGICAL OPERATORS

UPDATE

DISTINCT

ORDER BY

LIMIT

Aggregation

ForEach Map

MongoDB Assignment for Practice

TCET Session Data