Node.js Simple Backend Server

In this assignment you will be expected to write a backend system to handle saving and serving information to and from a client.

Most of the server code has already been provided for you - you will need to concentrate on the internal workings of the server (file system).

Getting started

Please run npm install before starting

What you will be doing

This project will teach you:

The difference between GET and POST requests
How to write files in Node.js
How to read files in Node.js

This project assumes you've already had experience with:

JavaScript
Frontend
Fetch API
Tools for testing APIs, such as Postman or Insomnia

Assignments

For the backend part of this assignment, you are expected to write your code in the file server.js

Assignment 1 - Test!

Let's perform a simple test to see if we can connect to our server.

In the console, run the command: nodemon server.js or node server.js

Hint: The difference between nodemon and node is that nodemon will automatically reload / reserve your file when you make changes. node will not.
Once your server is running, you can connect to it with one of your API testing tools (Postman, Insomnia)

Use this URL http://localhost:3000/save/user to connect to the server
What is the response?

Assignment 2 - Understanding the code

In the last assignment, we connected to the server using the path http://localhost:3000/save/user, but why this path?

The first part, http://localhost, is because we are running the server locally on our machines. But where does the rest come from?

Look at the code inside server.js. On the last line we have the following line app.listen(3000);. That number 3000 is known as the port. This is the port number to which the server is listening to.
Look again at the code inside server.js

Do you notice the function call, called app.post()?

This function call is listening for a path called /save/user

If we put this information together, we build the URL http://localhost:3000/save/user

Assignment 3 - Preparing to write data

For this assignment, we will be using the Node.js module, fs. Look over your notes regarding the Node.js file system.

Before you can use the fs module, we should import it:

const fs = require('fs');

Research: fs.writeFile()

Create a function which will write data to the server

The function should use the fs.writeFile() function

The function should either return a Promise

The function should take 2 arguments, filename and data

Assignment 4 - Writing data from the user

Update the app.post() function with the route /save/user:

Take the request.body value and stringify it

Hint: You will need to use the JSON.stringify() function
From inside the callback in app.post(), call the function you created in Assignment 2, passing in the data you stringified in the previous step. Also pass in an appropriate filename.
Test your code by making a POST request, sending a JSON object as the body. Include some test data here. When you make your request, it should create a new file with the data you passed in.

Hint: If your testing tool gives you the error Cannot GET /save/user, check you are making a POST and not a GET request

Assignment 5 - Reading data from a file

Research: fs.readFile()

Create a function which will write data to the server

The function should use the fs.readFile() function

The function should either return a Promise - OR - use a Promise natively

The function should take 1 argument, filename

The function should return or resolve with the data from the file

Assignment 6 - Sending data with a GET request

If you look at the code again, you should notice a function call, called app.get(). This is the GET request counterpart for your POST request. We will make this return a value.

From inside the callback in app.get(), call the function you created in Assignment 5, passing in the filename you wish to read from.

Hint: Remember, this function should return a Promise

If the Promise resolves:
1. Set the status of the response to 200 with the function response.status(200)
2. Send the file data back to the user via the function response.send()
If the Promise rejects:
1. Set the status of the response to 500 with the function response.status(500)

Assignment 7 - Build a frontend to make these calls

Build a frontend which will make both the GET and POST requests you were previously testing with your API testing tool.

The frontend should consist of a <form>, which will take the following details:
- First name
- Last name
- Age
- E-mail address
- Interests
There should be a button to Submit the form
Add a callback to the click event on the button to a POST request to the server
1. Put all your <form> input values into one object
2. Use JSON.stringify to stringify this object
3. Use the fetch API to send this object to your server endpoint, with the following options:
```
    method: 'post',
    headers: {
        'Accept': 'application/json, text/plain, */*',
        'Content-Type': 'application/json'
    },
    body: data
```
Look at the generated file on your server. It should contain all the data.
Add another button on your website which will do a fetch GET request to get the data from the server.
Display the results on your website

Flotsam3/nodejs-server-exercise