Sinatra PostgreSQL Grape Template

What is this good for?

• Development of simple REST API for web, mobile and desktop applications
• Isolation of code for web services
• An alternative to having one big Rails application with cluttered routes
• Sanity

Examples

• If you're writing an API implementation for various machine learning/ automation tasks, the best way is to isolate this and not make it a part of your probably bloated application
• REST API for specific mobile applications that may or may not rely another application

Dependencies

• Ruby 2.1.2 or greater
• Grape
• PostgreSQL
• Sinatra
• ActiveRecord
• will_paginate

Getting Started

$ git clone --depth 1 git://github.com/katgironpe/sinatra-pg-grape.git myapp
$ rm -r myapp/.git && rm myapp/README.md

PostgreSQL Configuration

Install PostgreSQL if you haven't yet.

On Mac OSX, you can use Homebrew to install PostgreSQL as

$ brew install pg

On Linux distros, use your package manager to install PostgreSQL. For instance, if you are on Ubuntu or Ubuntu derivative, you might use

$ apt-get install postgresql

You might need sudo privileges to run the above command. On CentOS-Fedora-Redhat, you would most likely use yum package manager. Similarly, on Arch, PostgreSQL can be installed with pacman.

Configuration

$ cp config/database.yml.example config/database.yml

Update config/database.yml.

Test Data

There's a rake task for loading test data.

bundle exec rake db:populate_db

After loading that data, you can check /api/v1/posts.

Start the application:

bundle exec shotgun config.ru

Use curl or probably just your browser to view the output:

curl http://localhost:9393/api/v1/posts

Grape Entity

With grape-entity, you can expose only the fields you want and format them as needed.

Testing

We can use RSpec and Rack::Test to test the API requests.

Here's an example:

#example.rb
class Example < Grape::API
  prefix 'api'
  version 'v1'
  format :json

  get :hello do
    { hello: 'Hello world' }
  end
end

We should make sure it returns correct status code and output:

require 'spec_helper'

describe Example do
  include Rack::Test::Methods

  def app
    Example
  end

  describe 'GET /api/v1/hello' do
    it 'says hello to the world' do
      get '/api/v1/hello'
      expect(last_response.status).to eq(200)
      expect(JSON.parse(last_response.body)['hello']).to eq('Hello world')
    end
  end
end

Use the commands:

bundle exec rake

The Golden Rule of API Design

It’s not enough to write tests for an API you develop; you have to write unit tests for code that uses your API.

— Michael Feathers

Have any questions/ suggestions?

Katherine Pe

• c.kat.pe