CRUD APIs & Express (Class 37-38)

Question 1

What is internet?

Answer 1

A wire connecting client side and server side.
Browser running on client side sends a request to server, server heard our request (through lines of codes, known as API) and respond back

Question 2

When you type in url and enter, what happens?

Answer 2

You are making a get request to a server, and we can code our server to hear that request and to know what to do when it hears it.

Question 3

What is CRUD?

Answer 3

Create (post) - Make something
Read (get) - Get something
Update (put) - Change something
Delete (delete) - Remove something

Question 4

Using instagram as an example, what are some Create (post) requests?

Answer 4

Making a new post on instagram (I am sending data to a server and the server use the data to make a new post)

Question 5

Using instagram as an example, what are some Read (get) requests?

Answer 5

Scrolling through your feed or looking at individual post of your friend (I am asking server to get me the data)

Question 6

Using instagram as an example, what are some Update (put) requests?

Answer 6

Editing a comment or click the like (or love) icons (If my like goes from 0 to 1, I am updating something on the server)

Question 7

Using instagram as an example, what are some Delete (delete) requests?

Answer 7

Deleting a post

Question 8

In the browser, if i type instagram.com, what type of request is client making?

Answer 8

Get (Read) request

Question 9

When I like the photo on instagram, what kind of a request is client making?

Answer 9

Put (Update) request
and lines of code (API) in the server hears the request and respond back

Question 10

Why requires 2 steps for liking the instagram post?

Answer 10

1. Client send put request (Update) when liking a photo (to update data)
2. Server updated the data and refresh the page (refreshing trigger a new GET request and send new updated HTML)

Same is true with delete request

Question 11

When I create a new post on instagram, what kind of a request is client making?

Answer 11

1. Client sending Post (Create) request
2. API in the server hears the request and respond by creating a new post for client
3. When everything went ok, browser will refresh and send Read (Get) request and display a new post

Question 12

What is Express?

Answer 12

Fast, un-opinionated, minimalist web framework for Node.js.

With a myriad of HTTP utility methods and middleware at your disposal, creating a robust API is quick and easy

Question 13

What is middleware?

Answer 13

A lot of stuff happens in between a request coming in and response going out. All the tools and things that help the process between the request and response

Question 14

What is express (in simple terms)?

Answer 14

Web framework for node.js (can only be used with node.js)
(just like django for python, ruby on rails for Ruby, etc)

Question 15

Key steps before building

Answer 15

mkdir api-project
cd api-project
npm init
npm install express –save

Question 16

what is npm init?

Answer 16

Create package.json file

Question 17

const express = require(“express”)
const app = express()

app.get(“/”,(request, response) => {

})

Answer 17

const express: This declares a constant variable named express. Constants are variables whose values cannot be re-assigned. In this case, express is the name of a Node.js module used for creating web applications.

require(“express”): This is a Node.js function used to import modules. Here, it imports the express module, which is a popular framework for building web applications in Node.js.

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const app = express();
const app: This declares another constant variable named app. This variable will hold our Express application.

express(): This invokes the express function, creating a new instance of an Express application. This instance represents your entire web application.

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app.get(“/”,(request, response) => {

});
app.get(“/”): This sets up a route handler for HTTP GET requests to the root URL (“/”) of your application. It tells Express to execute the provided callback function when a GET request is made to the root URL.

(request, response) => { … }: This is an arrow function, which is the callback function that will be executed when a GET request is made to the root URL. It takes two parameters: request (an object representing the HTTP request) and response (an object representing the HTTP response). Inside this function, you define the logic to handle the request and send a response back to the client.

Overall, these lines of code initialize an Express application, set up a route handler for the root URL (“/”), and define the logic to handle GET requests to that route.

Question 18

How to start a server?

Answer 18

node server.js

Question 19

What does server.js file usually contain?

Answer 19

Contains the code to create and listen on a network port (usually contains modules like “http” or express framework

Question 20

Common workflow

Answer 20

1. Install Node.js:
   npm init in terminal
2. Install Express
   npm install express
3. Create server.js file
4. Start the Server
   node server.js