homework.md

Homework

• create a repository/folder
• initialize the repository
• Install express
• create a server
• listen to port 7777
• write request handlers for /test , /hello
• install nodemon and update scripts inside package.json

Read more about it

• node modules , package.json , package-lock.json
• what are dependencies
• what is the use of "-g" while npm install
• difference b/w caret and tilda (~ vs ^)

Github homework

• initialize git
• create a gitignore file and put file and folder which we don't want to push on the github
• create a remote repo on github and connect the local repo with this remote repo
• push all the local repo on the remote repo.
• play with the routes and routes extensions ex. /hello, / , /hello/2, /xyz

Important Lesson

• order of the routes matter most

HTTP methods

• Install Postman app and make a workspace/collection => test API calls
• Write Logic to handle GET, POST , PATCH, PUT, DELETE and test them on Postman
• POST
• GET
• PATCH
• PUT
• DELETE

API routes

• Exploring routing and use of ?, +, *, (), in the routes
• use of regex in routes /a/, /.*fly$/
• reading the query params in the routes
• reading the dynaminc routes

/* ? , + , * all have diffrent meanings and can be used in creating routes and we can also group them together ex - /ab?c -> /abc , /abbc {b is optional parameter}

• /ab+c -> /abc , /abbc , /abbbbc {b can be repeated any number of times}
• /ab*cd -> abkasjkdhcd {you can add anything in between ab and cd} */

Middleware and Error handler

• Multiple route handlers - play with the code
• next()
• next function and errors along with the res.send()
• app.use('/route', rH, [rH2, rH3], rH4, rH4);

/* multpli route handlers signatures r1 r2 r3 r4 r5 reperesent request handler functions app.use('/user' , r1 , r2 , r3 , r4 , r5); or app.use('/user' , [r1 , r2 , r3 , r4 , r5]); or app.use('/user' , (r1 , r2 , r3 , r4 , r5)); or app.use('/user' , [r1 , r2 , r3 , r4] , r5); */

• what is middlewares
• how express js handles request behind the scenes
• app.use() vs app.all() there is small difference b/w routing
• write a dummy auth midddleware for admin
• write a dummy auth middleware for user
• error handling using app.use('/', (err , req, res, next) => {}); put these lines at the end of the code

Database homeworkk

• create freec cluster on MongoDB official website (mongo atlas)

• Install mongoDB comapass

• Create a config Folder for database configuration with database,js file :- config/database.js

• connect your application to the database "connectionString/devTinder"

• call the connectToDB fucntion and connect to database before starting application on 3000

• create a User Schema & user Model

• create /signup API to add data to database

• push some data using API calls from POSTMAN

• do some error handling using try-catch

• Javascript object vs JSON object {differences}

• Add the express.json() middleware to your app

• Make your signup API to receive data from the end User{server , browser, console}

• User.findOne() with duplicate email , which mongoose object return from the database

• API -> Get user by email

• API -> feed API - GET/feed :- that get all the user from database

• API -> Get user by Id

• API -> create a delete user API

• Difference between PPATCH and PUT

• Explore the Mongoose documentation method specifically for Mongoose Model methods

• What are the options in a Model.findOneAndUpdate method , explore more about it

• API -> create an API to update user data by using userId

• API -> create an API to update user data by using email

Data Sanitiztion and schema validation

schema validation

• Explore scehmatype options from the mongoose documentation
• add validation like required, trim, min, minLength , maxLength, lowercase, unique
• Add default
• Create a custom validate function for gender and add runValidators in API
• Improve the DB schema Put all appropriate validations on each feild in schema
• Add timestamp in user schema
• Data Sanitizaton - Add API validation on patch request and signup post api
• Add API validation for each feild
• install validator npm pakage
• Explore validator library functions and use validator funcs for password, email, photoUrl

Never trust req.body

Encrypting Password

• Validating SignUp API data by creating helper function
• Install bcrypt package
• create a passwordHash using bcrypt.hash() and save the encrypted password of the user...
• create login API
• Compare password and throw errors if email or password is invalid

Authentication , JWT and Cookies

• Install cookie-parser and require in app.js and send dummy cookie from login API
• create a GET/profile API and check if you get the cookie back
• Install jsonwebtoken and require in app.js
• In login API , after email and password validation, create a JWT token and send it to user in cookies
• read the cookies inside your profile API and find the logged in user
• Write the userAuth middleware
• add the userAuth middleware in profile API and a new sendConnectionRequest API
• set the expiry of JWT token and cookies to 7 days
• create userSchema methods to getJWT()
• create userSchema methods to comparePassword(passwordInputByUser)

Diving into the APIs and the express.Router()

• Explore the tinder API in developer console

• create a list of APIs you can think of ur own in devtinder

• Group multiple routes under respective or specific router

• Making the habit of exploring the APIs of almost daily used websites like banking , e-commerce , social media and many others in developer console

• Name your APIs properly which helps in categorise and Grouping in a Specific Router . it will also helps to avoid confusion just by reading the API i can understand what this API is doing..

• Read documentation for express.Router();

• create routes/folder for managing auth , profile and connectionRequest routers

• create auth router, profile router, connectionRequest router

• import these router in our app.js

Logical db query & compound indexes

• create a connectionRequestSchema

• create a connectionRequest Model

• Send connection request API

• proper validation on data

• Think about all corner cases and handle them

• Read about {$or} and {$and} in mongoose

• read about schema.pre() and schema.post() functions

• ALWAYS THINK ABOUT CORNER CASES AND HANDLE THEM

• read more about indexes in mongodb

• why do we need indexes in database

• advantages and disadvantages of creating indexes

• read about compound indexes and how to create them

Ref , Populate and thoughts process of Writng APIs

• write code with proper validation of this API "/request/review/:status/:requestId"

• Thoughts process of writing APIs : GET vs POST

• ref and populate the user model in connectionRequestSchema and how the relationship is created

• building the feed API // user should see all the user cards except // 0. his own user card // 1. his own connections // 2. ignored people (jinko ignore kr diya hai) // 3. already sent connection requests to someone // 4. already received connection requests from someone

  // example : Piyush , Neha , Rohit , virat , Khushi -- all are registered user // Anu is a new user coming to our platform he see the cards of all the above registered users except himself at initial level // Anu ->(connection sent) piyush ->(status) accepted then both of them will not see each other's cards on their profile // Anu ->(connection sent) neha ->(status) rejected then both of them will not see each other's cards on their profile //in Piyush feed : Neha , Rohit , virat , Khushi except Anu //in Neha feed : Piyush , Rohit , virat , Khushi except Anu

  • Logic to build the feed API -> GET/user/feed

  • Explore the $nin and $ne operators in mongoose

  • Pagination in the feed API

  • /user/feed?page=1&limit=10 .skip(0)&limit(10)

  • :- it returns the first 10 user on the feed page 1

  • skip = (pageNumber - 1) * limit

  • /user/feed?page=1&limit=10 .skip(10)&limit(10)

  • :- it returns the next 10 user on the feed page 2 from 11 to 20

  • In mongodb we have two most important function

  • skip() function: to skip the first n records and

  • limit() function: to limit the number of records to max m records