How to create a REST API Using Express Module #66

Question 1

Pop quiz! What are the first 2 lines of code we always write when using Express.js?

Answer 1

1. Require the library
2. Declare a variable for our app and assign express( ) to it

const express = require('express')
const app = express( )

Question 2

What line of code is required in order to start up the express server instance?

Answer 2

app.listen(3000, ( ) => console.log(“Server is ready Captain!”)

You can choose any port you want as long as it isn’t in use. I used 3005 because somehow I had a port conflict.

Question 3

Defining endpoints: which two params are accepted when writing endpoints?

Answer 3

The path to watch/listen and a callback function that is triggered when a new connection happens.

Example:
app.get(“/”, (req, res) => { /* Actions */ } )

Question 4

What parameters are received when we run these express handlers?

app. get(‘/’, (req, res) => { /* / })
app. post(‘/’, (req, res) => { / / })
app. put(‘/’, (req, res) => { / / })
app. delete(‘/’, (req, res) => { / / })
app. patch(‘/’, (req, res) => { / */ })

Answer 4

( req, res ) =

Request, Response
They are variables and subject to whatever we want to call them. The order though needs to have the request first and I see no need to rename these to anything else that might be less readable.

Question 5

How is the response object used when working with API’s

Answer 5

It is used to return information back to the user/client.

Question 6

How are GET requests for the root directory handled?

Answer 6

They are handled automatically.

Question 7

What’s the basic syntax for handling other directories or paths that you create?

Answer 7

app.get(“path”, (req, res) => { } )

Question 8

Using Express, how can we send a response about the status of a request?

Answer 8

app.get(‘/dogs/”id”, (req, res) => {
res.status(404)
res.status(‘Dog not found’)
} )

The status and message can also be chained.

Question 9

What language is used to serve up the response object?

Answer 9

JSON. Examples below:

app.get('/dogs', (req, res) => {
  const dogs = []
  dogs.push({ name: 'Roger' })
  dogs.push({ name: 'Syd' })
  res.json(dogs)
})

app.get('/dogs/:id', (req, res) => {
  const dogs = [{
		id: 1,
     name: 'Roger'
	}]

  const dog = dogs.filter(dog => dog.id === req.params.id)
  if (dog.length) {
    res.json(dog[0])
  } else {
    res.status(404).send('File not found')
  }
})

Question 10

What does the basic syntax of a POST request look like in Express JS?

Answer 10

app.post(‘/’, (req, res) => { //do stuff })

Question 11

What does the syntax look like in order to accept a JSON object

Answer 11

app.use(express.json( )) then you get the request body inside the request handler.

app.post('/dog', (req, res) => {
  const dog = {
    name: req.body.name,
    age: req.body.age
  }
  //we have the dog data, we can go on
})

Question 12

What is the most common way to send form data?

Answer 12

by sending URL encoded data. Example:

{
  "name": "Roger",
  "age": 8
}
 Or when sent URL-encoded on the server-side looks like name=Roger&age=8.

Question 13

How is a fetch request structured?

Answer 13

fetch(baseurl + '/dog', {
  "method": "POST",
  "headers": {
    "content-type": "application/x-www-form-urlencoded",
  },
  "body": {
    "name": "Roger",
    "age": 8
  }
})

Question 14

There is a much different way to set up a way to handle URL encoded data from a server. How is that set up?

Answer 14

app.use(express.urlencoded({ extended: true }))

The data then becomes available in the body property just like the JSON request like this:

app.post('/dog', (req, res) => {
  const dog = {
    name: req.body.name,
    age: req.body.age
  }
  //we have the dog data, we can go on
})

The way it is “POSTed” is the same

Question 15

What is the PUT method used for?

Answer 15

Udatating data on the server.

Question 16

How is the most basic form of a PUT request structured?

Answer 16

Basically it’s app.put
except there is an ID in the URL
app.put(‘/dog/:id’, (req, res) => {})

Question 17

Let’s say we want to update the data of something we already have on the server? What does that look like?

Answer 17

It looks much the same as a POST request. Example:

const express = require('express')
const app = express()

app.use(express.json())

app.put('/dog/:id', (req, res) => {
  const dog = {
    name: req.body.name,
    age: req.body.age
  }
  //we have the new dog data, we can update it
})

OR URL encoded data like this

const express = require('express')
const app = express()

app.use(express.urlencoded({ extended: true }))

app.put('/dog/:id', (req, res) => {
  const dog = {
    name: req.body.name,
    age: req.body.age
  }
  //we have the new dog data, we can update it
})

Question 18

PATCH is also used to update data resources, but how does it differ from PUT?

Answer 18

Patch only partially updates a resource. For example we can update the age of somebody without touching the rest of the data object.

Here’s what it looks like:

app.patch(‘/dog/:id’, (req, res) => {})

Question 19

In what way is PATCH the same as the PUT method?

Answer 19

You still need to include the /:id in the URL because we want to partially update a specific record. Here’s an example:

const express = require('express')
const app = express()

app.use(express.json())

app.patch('/dog/:id', (req, res) => {
  const age = req.body.age
  //we have the new dog age, we can update it
})

OR for URL encoded data

const express = require('express')
const app = express()

app.use(express.urlencoded({ extended: true }))

app.patch('/dog/:id', (req, res) => {
  const age = req.body.age
  //we have the new dog age, we can update it
})

Question 20

DELETE is used for deleting resources, but how is it written?

Answer 20

const express = require('express')
const app = express()

app.delete('/dog/:id', (req, res) => {
  //delete the dog with the specified `id`  from our database
})
A response with a 200 status code:

const express = require('express')
const app = express()

app.delete('/dog/:id', (req, res) => {
  //delete the dog with the specified `id`  from our database

// …

res.status(200).send(‘OK’)
})