I had a MySQL schema from a booking.com like platform. I wanted to generate REST API very fast from my MySQL database tables. Like I have a table named hotels. I want to generate following endpoints:

GET    /api/hotels
GET    /api/hotels/:id
POST   /api/hotels
PUT    /api/hotels/:id
DELETE /api/hotels/:id

I tried to use Haskell but the security was very low on postgrest package in Haskell. The postgrest is amazing, it generates the api endpoints from a database. But the problem is it will delete all the rows in a table if I perform a DELETE request in /api/hotels. So, I can not use it.

Finally found that Kemal Rest API is the perfect for doing this which is on Crystal Lang. Suppose I have a table named hotels. This is what I did. I installed Crystal Lang. I ran shards init app hotel to generate an empty project. shards is the dependency manager, task runner for crystal. So after this I have a folder named hotel which has the following structure:

├── README.md
├── db.sql
├── shard.lock
├── shard.yml
├── spec
│   ├── hotel_spec.cr
│   └── spec_helper.cr
└── src
    └── hotel.cr

I have modified the shard.yml file and added following lines at the end.

    github: crystal-lang/crystal-db
    github: kemalcr/kemal
    github: blocknotes/kemal-rest-api
    github: crystal-lang/crystal-mysql

I have ran the shards install to install the libraries and modified the hotel.cr file like following:

require "db"
require "mysql"
require "kemal"
require "kemal-rest-api"
require "json"

DB_NAME       = "hotel"
DB_CONNECTION = "mysql://hotel@localhost/#{DB_NAME}"

class MyModel < KemalRestApi::Adapters::CrystalDbModel
  def initialize
    super DB_CONNECTION, "hotels"

module WebApp
  res = KemalRestApi::Resource.new MyModel.new, KemalRestApi::ALL_ACTIONS, prefix: "api", singular: "hotel"

  # Routes
  get "/" do |env|
    env.response.content_type = "application/json"
    {name: "--", info: "--", version: "0.0.1"}.to_json


  # Starts Kemal

to generate these routes automatically:

GET    /api/hotels
GET    /api/hotels/:id
POST   /api/hotels
PUT    /api/hotels/:id
DELETE /api/hotels/:id

At last I have ran shards build to make the binary executable file. And ran it like ./bin/hotel. And the API is working properly.

The Crystal code is just like Ruby language but as fast as C. What I need to do next is make an array of tables and it will generate the API endpoints. I don’t need to take hassle about images and users because we already have other microservices to handle those. Also, this API will never be exposed to clients rather another API wrapper will fetch data from it. So, I found it perfect fit for my job.

Thus I have made my hotel API up in just couple of hours.