JSON Server (json-server)

Today we will look into a very handy tool json-server, which can give you a mock rest json server in a minute. In a regular enterprise application, you work with many teams and third party APIs. Imagine you have to call a third party restful web service that will get you JSON data to work on. You are in a tight schedule, so you can’t wait for them to finish their work and then start your own. If you wish to have a mockup Rest Web service in place to get the demo data for you, then json-server is the tool you are looking for.

JSON Server

JSON Server is a Node Module that you can use to create demo rest json webservice in less than a minute. All you need is a JSON file for sample data.

Installing JSON Server

You should have NPM installed on your machine. If not, then refer this post to install NPM. Below shows the one liner command to install json-server with output on my machine.

$ npm install -g json-server
npm WARN deprecated graceful-fs@3.0.8: graceful-fs v3.0.0 and before will fail on node releases >= v7.0. Please update to graceful-fs@^4.0.0 as soon as possible. Use 'npm ls graceful-fs' to find it in the tree.
/usr/local/bin/json-server -> /usr/local/lib/node_modules/json-server/bin/index.js
- bytes@2.3.0 node_modules/json-server/node_modules/raw-body/node_modules/bytes
/usr/local/lib
└─┬ json-server@0.8.10
  ├─┬ body-parser@1.15.1
  │ └── bytes@2.3.0
  ├─┬ compression@1.6.1
  │ └── bytes@2.2.0
  ├─┬ lowdb@0.10.3
  │ └─┬ steno@0.4.4
  │   └── graceful-fs@4.1.4
  ├─┬ update-notifier@0.5.0
  │ └─┬ configstore@1.4.0
  │   ├── graceful-fs@4.1.4
  │   └─┬ write-file-atomic@1.1.4
  │     └── graceful-fs@4.1.4
  └─┬ yargs@4.7.0
    ├─┬ pkg-conf@1.1.2
    │ └─┬ load-json-file@1.1.0
    │   └── graceful-fs@4.1.4
    └─┬ read-pkg-up@1.0.1
      └─┬ read-pkg@1.1.0
        └─┬ path-type@1.1.0
          └── graceful-fs@4.1.4

$

Checking json-server version and options

$ json-server -v
0.8.10

$ json-server -help
/usr/local/bin/json-server [options] <source>

Options:
  --config, -c       Path to config file           [default: "json-server.json"]
  --port, -p         Set port                                    [default: 3000]
  --host, -H         Set host                               [default: "0.0.0.0"]
  --watch, -w        Watch file(s)                                     [boolean]
  --routes, -r       Path to routes file
  --static, -s       Set static files directory
  --read-only, --ro  Allow only GET requests                           [boolean]
  --no-cors, --nc    Disable Cross-Origin Resource Sharing             [boolean]
  --no-gzip, --ng    Disable GZIP Content-Encoding                     [boolean]
  --snapshots, -S    Set snapshots directory                      [default: "."]
  --delay, -d        Add delay to responses (ms)
  --id, -i           Set database id property (e.g. _id)         [default: "id"]
  --quiet, -q        Suppress log messages from output                 [boolean]
 
$

Run JSON Server

Now it’s time to start our json-server. Below is a sample file with my employees json data.

{
  "employees": [
    {
      "id": 1,
      "name": "Pankaj",
      "salary": "10000"
    },
    {
      "name": "David",
      "salary": "5000",
      "id": 2
    }
  ]
}

Important point here is the name of array i.e employees. JSON server will create the REST APIs based on this. Let’s start our json-server with above file.

$ json-server --watch db.json

  \{^_^}/ hi!

  Loading db.json
  Done

  Resources
  https://localhost:3000/employees

  Home
  https://localhost:3000

  Type s + enter at any time to create a snapshot of the database
  Watching...

Don’t close this terminal, otherwise it will kill the json-server. Below are the sample CRUD requests and responses.

JSON Server GET - Read All Employees

$ curl -X GET -H "Content-Type: application/json"  "https://localhost:3000/employees"
[
  {
    "id": 1,
    "name": "Pankaj",
    "salary": "10000"
  },
  {
    "name": "David",
    "salary": "5000",
    "id": 2
  }
]
$

Get Employee based on ID from json-server

$ curl -X GET -H "Content-Type: application/json"  "https://localhost:3000/employees/1"
{
  "id": 1,
  "name": "Pankaj",
  "salary": "10000"
}
$

JSON Server POST - Create an Employee

$ curl -X POST -H "Content-Type: application/json" -d '{"name": "Lisa","salary": "2000"}' "https://localhost:3000/employees"
{
  "name": "Lisa",
  "salary": 2000,
  "id": 3
}
$

JSON Server PUT - Update Employee Data

$ curl -XPUT -H "Content-Type: application/json" -d '{"name": "Lisa", "salary": "8000"}' "https://localhost:3000/employees/3"
{
  "name": "Lisa",
  "salary": 8000,
  "id": 3
}
$

JSON Server DELETE - Delete an Employee

$ curl -X DELETE -H "Content-Type: application/json"  "https://localhost:3000/employees/2"
{}
$ curl -GET -H "Content-Type: application/json"  "https://localhost:3000/employees"
[
  {
    "id": 1,
    "name": "Pankaj",
    "salary": "10000"
  },
  {
    "name": "Lisa",
    "salary": 8000,
    "id": 3
  }
]
$

As you can see that with a simple JSON, json-server creates demo APIs for us to use. Note that all the PUT, POST, DELETE requests are getting saved into db.json file. Now the URIs for GET and DELETE are same, similarly it’s same for POST and PUT requests. Well, we can create our custom URIs too with a simple mapping file.

json-server custom routes

Create a file with custom routes for our json-server to use. routes.json

{
  "/employees/list": "/employees",
  "/employees/get/:id": "/employees/:id",
  "/employees/create": "/employees",
  "/employees/update/:id": "/employees/:id",
  "/employees/delete/:id": "/employees/:id"
}

We can also change the json-server port and simulate like a third party API, just change the base URL when the real service is ready and you will be good to go. Now start the JSON server again as shown below.

$ json-server --port 7000 --routes routes.json --watch db.json
(node:60899) fs: re-evaluating native module sources is not supported. If you are using the graceful-fs module, please update it to a more recent version.

  \{^_^}/ hi!

  Loading db.json
  Loading routes.json
  Done

  Resources
  https://localhost:7000/employees

  Other routes
  /employees/list -> /employees
  /employees/get/:id -> /employees/:id
  /employees/create -> /employees
  /employees/update/:id -> /employees/:id
  /employees/delete/:id -> /employees/:id

  Home
  https://localhost:7000

  Type s + enter at any time to create a snapshot of the database
  Watching...

It’s showing the custom routes defined by us.

json-server example with custom routes

Below is the example of some of the commands and their output with custom routes.

$ curl -X GET -H "Content-Type: application/json"  "https://localhost:7000/employees/list"
[
  {
    "id": 1,
    "name": "Pankaj",
    "salary": "10000"
  },
  {
    "name": "Lisa",
    "salary": 8000,
    "id": 3
  }
]

$ curl -X GET -H "Content-Type: application/json"  "https://localhost:7000/employees/get/1"
{
  "id": 1,
  "name": "Pankaj",
  "salary": "10000"
}

$ curl -X POST -H "Content-Type: application/json" -d '{"name": "Lisa","salary": "2000"}' "https://localhost:7000/employees/create"
{
  "name": "Lisa",
  "salary": 2000,
  "id": 4
}

$ curl -XPUT -H "Content-Type: application/json" -d '{"name": "Lisa", "salary": "8000"}' "https://localhost:7000/emloyees/update/4"
{
  "name": "Lisa",
  "salary": 8000,
  "id": 4
}

$ curl -XDELETE -H "Content-Type: application/json"  "https://localhost:7000/employees/delete/4"
{}

$ curl -GET -H "Content-Type: application/json"  "https://localhost:7000/employees/list"
[
  {
    "id": 1,
    "name": "Pankaj",
    "salary": "10000"
  },
  {
    "name": "Lisa",
    "salary": 8000,
    "id": 3
  }
]
$

JSON server provides some other useful options such as sorting, searching and pagination. That’s all for json-server, it’s my go to tool whenever I need to create demo Rest JSON APIs. Reference: json-server GitHub