JSON Server tutorial
last modified October 18, 2023
JSON Server tutorial introduces the JavaScript json-server library,
which can be used to create fake REST API.
JSON server
The json-server is a JavaScript library to create testing REST API.
JSON Server installation
First, we create a project directory an install the json-server module.
$ mkdir json-server-lib $ cd json-server-lib $ npm init -y $ npm i -g json-server
The JSON server module is installed globally with npm.
$ npm install axios
In addition, we install the axios module, which is a promise-based
JavaScript HTTP client.
$ cat package.json
{
"name": "json-server-lib",
"version": "1.0.0",
"description": "",
"main": "index.js",
"dependencies": {
"axios": "^0.18.0"
},
"devDependencies": {},
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"keywords": [],
"author": "",
"license": "ISC"
}
This is our package.json file.
JSON test data
We have some JSON test data:
{
"users": [
{
"id": 1,
"first_name": "Robert",
"last_name": "Schwartz",
"email": "rob23@gmail.com"
},
{
"id": 2,
"first_name": "Lucy",
"last_name": "Ballmer",
"email": "lucyb56@gmail.com"
},
{
"id": 3,
"first_name": "Anna",
"last_name": "Smith",
"email": "annasmith23@gmail.com"
},
{
"id": 4,
"first_name": "Robert",
"last_name": "Brown",
"email": "bobbrown432@yahoo.com"
},
{
"id": 5,
"first_name": "Roger",
"last_name": "Bacon",
"email": "rogerbacon12@yahoo.com"
}
]
}
Starting JSON server
The JSON server is started with the json-server, which we have
installed globally.
$ json-server --watch users.json
The --watch command is used to specify the data for the server.
$ curl localhost:3000/users/3/
{
"id": 3,
"first_name": "Anna",
"last_name": "Smith",
"email": "annasmith23@gmail.com"
}
With the curl command, we get the user with Id 3.
JSON Server GET request
In the next example we retrieve data with a GET request.
const axios = require('axios');
axios.get('http://localhost:3000/users')
.then(resp => {
data = resp.data;
data.forEach(e => {
console.log(`${e.first_name}, ${e.last_name}, ${e.email}`);
});
})
.catch(error => {
console.log(error);
});
With the axios module, we get all users as a JSON array and loop through
it with forEach.
$ node get_request.js Robert, Schwartz, rob23@gmail.com Lucy, Ballmer, lucyb56@gmail.com Anna, Smith, annasmith23@gmail.com Robert, Brown, bobbrown432@yahoo.com Roger, Bacon, rogerbacon12@yahoo.com
This is the output of the example. We get all users and print their full names and emails.
JSON Server POST request
With a POST request, we create a new user.
const axios = require('axios');
axios.post('http://localhost:3000/users', {
id: 6,
first_name: 'Fred',
last_name: 'Blair',
email: 'freddyb34@gmail.com'
}).then(resp => {
console.log(resp.data);
}).catch(error => {
console.log(error);
});
A new user is created with axios.
$ node post_request.js
{ id: 6,
first_name: 'Fred',
last_name: 'Blair',
email: 'freddyb34@gmail.com' }
The server responds with a newly created object.
$ curl localhost:3000/users/6/
{
"id": 6,
"first_name": "Fred",
"last_name": "Blair",
"email": "freddyb34@gmail.com"
}
We verify the newly created user with the curl command.
JSON Server modify data with PUT request
In the following example we modify data with a PUT request.
const axios = require('axios');
axios.put('http://localhost:3000/users/6/', {
first_name: 'Fred',
last_name: 'Blair',
email: 'freddyb34@yahoo.com'
}).then(resp => {
console.log(resp.data);
}).catch(error => {
console.log(error);
});
In the example, we modify the user's email address.
$ node put_request.js
{ first_name: 'Fred',
last_name: 'Blair',
email: 'freddyb34@yahoo.com',
id: 6 }
JSON Server DELETE request
In the following example, we show how to delete a user with a DELETE request.
const axios = require('axios');
axios.delete('http://localhost:3000/users/1/')
.then(resp => {
console.log(resp.data)
}).catch(error => {
console.log(error);
});
In the example, we delete the user with Id 1.
$ node delete_request.js
{}
The server responds with empty JSON data.
JSON Server sorting data
In the next example, we sort our data.
const axios = require('axios');
axios.get('http://localhost:3000/users?_sort=last_name&_order=asc')
.then(resp => {
data = resp.data;
data.forEach(e => {
console.log(`${e.first_name}, ${e.last_name}, ${e.email}`)
});
}).catch(error => {
console.log(error);
});
The code example sorts data by the users' last name in ascending order.
We use the _sort and _order query parameters.
$ node sort_data.js Roger, Bacon, rogerbacon12@yahoo.com Lucy, Ballmer, lucyb56@gmail.com Fred, Blair, freddyb34@yahoo.com Robert, Brown, bobbrown432@yahoo.com Robert, Schwartz, rob23@gmail.com Anna, Smith, annasmith23@gmail.com
JSON Server operators
We can use _gte and _lte for getting a specific range
of data.
const axios = require('axios');
axios.get('http://localhost:3000/users?id_gte=4')
.then(resp => {
console.log(resp.data)
}).catch(error => {
console.log(error);
});
The code example show users with id greater than or equal to 4.
$ node operators.js
[ { id: 4,
first_name: 'Robert',
last_name: 'Brown',
email: 'bobbrown432@yahoo.com' },
{ id: '5',
first_name: 'Roger',
last_name: 'Bacon',
email: 'rogerbacon12@yahoo.com' },
{ first_name: 'Fred',
last_name: 'Blair',
email: 'freddyb34@yahoo.com',
id: 6 } ]
JSON Server full text search
A full text search can be performed with the q parameter.
const axios = require('axios');
axios.get('http://localhost:3000/users?q=yahoo')
.then(resp => {
console.log(resp.data)
}).catch(error => {
console.log(error);
});
The code example searches for the yahoo term.
$ node full_text_search.js
[ { id: 4,
first_name: 'Robert',
last_name: 'Brown',
email: 'bobbrown432@yahoo.com' },
{ id: '5',
first_name: 'Roger',
last_name: 'Bacon',
email: 'rogerbacon12@yahoo.com' },
{ first_name: 'Fred',
last_name: 'Blair',
email: 'freddyb34@yahoo.com',
id: 6 } ]
The search query returned these three users.
Source
In this article we have introduced the JSON Server JavaScript library.
