Real basic REST API server in one script

SinatraAPI.rb

#!/usr/bin/env ruby
#
# stevie_chambers@viewyonder.com July 2012
#
# I'm playing around with APIs, and sharing my learnings
# You can follow my trials and tribulations at http://viewyonder.com/apis
#
# This is a simple Ruby script to show how a simple API might work.
# The resource model is just a simple array of a single class - no back-end store (yet)
#
# This will take browser/curl on all four CRUD verbs and hopefully give the right HTTP responses :)
# 
# Open the API root for more 'documentation'

require 'sinatra'
require 'JSON'

API_VERSION='2012-07-10'

# Our complex resource model :)  We have a hash of these, key is id.  That's it; that's all
class Person
  attr_accessor :id, :name
  def initialize(id,name)
    @id = id
    @name = name
  end
end
steve = Person.new('1','Steve')
alan = Person.new('2','Alan')
dave = Person.new('3','Dave')
team = { '1' => steve, '2' => alan, '3' => dave } 

# This bad boy is called at the end of every route to push (some of) the client's request headers for debugging.
def request_html(request)
  html = Array.new
  html << "<h3>Debugging</h3>"
  html << "<p>Team API Version X-Api-Header - #{API_VERSION}</p>"
  html << "<p>Request Method - #{request.request_method}</p>"
  html << "<p>URL - #{request.url}</p>" 
  html << "<p>Accept - #{request.accept}</p>"              
  html << "<p>Body - #{request.body}</p>"                
  html << "<p>Query String - #{request.query_string}</p>"
  html << "<p>Content Length - #{request.content_length}</p>"
  html << "<p>Media Type - #{request.media_type}</p>"       
  html << "<p>HEADER - #{request["SOME_HEADER"]}</p>"  # Use this later to authentication    
  html << "<p>User Agent - #{request.user_agent}</p>"     
  html
end

def doc_html
  html = Array.new
  html << "<h3>Documentation</h3>"
  html << "<p>This version uses all the CRUD verbs - in order, POST, GET, PUT, DELETE.</p>"
  html << "<p>The only resource in the API is /api/team and in there each member has a unique number ID.</p>"
  html << "<p>This team resource is a simple hash of a simple class called Person with id and name attributes.</p>"
  html << %{<li>Create a specific resource: curl -X POST -i -d '{ "id": "666", "name" : "Jeramiah" }' http://localhost:4567/api/team/666</li>}  
  html << %{<li>Read a specific resource: curl -X GET -i http://localhost:4567/api/team/666</li>}  
  html << %{<li>Update a specific resource: curl -X PUT -i -d '{ "id": "666", "name" : "Satan" }' http://localhost:4567/api/team/666</li>}  
  html << %{<li>Delete a specific resource: curl -X DELETE -i http://localhost:4567/api/team/666</li></ul>}  
  html
end

# Sinatra server root, not the api root (that's /api, not /)
get '/' do
  html = Array.new
  html << %{<h1>Sinatra Web Server</h1>}
  html << %{<h3>Resources</h3>}
  html << %{<p><a href="/api" rel="api">Team API Root End Point</a></p>}
  request_html(request).each { |p| html << p }

  status 200 # OK
  content_type 'text/html'
  body(html)
end

# The Team API root, so we give some useful info here on how to use, what's done, what's not done.
get '/api/?' do
  html = Array.new
  html << %{<h1>Team API</h1>}
  doc_html.each { |p| html << p }
  html << %{<h3>Resources</h3>}
  html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
  request_html(request).each { |p| html << p }

  status 200 # OK
  content_type 'text/html'
  body(html)
end

get '/api/team/?' do
  html = Array.new
  html << %{<h1>Team Resources</h1>}
  doc_html.each { |p| html << p }
  html << %{<h3>Resources</h3>}
  team.each do |key, person|
    html << %{<li><a href="/api/team/#{person.id}" rel="#{person.name}">#{person.name}</a></li>}
  end
  html << %{<p><a href="/api" rel="api">Team API Root End Point</a></p>}
  request_html(request).each { |p| html << p }

  status 200 # OK
  content_type 'text/html'
  body(html)
end

get '/api/team/:id' do
  person = team[params[:id]]
  if person.nil? then
    html = Array.new
    html << %{<h1>Team Resource - Error</h1>}
    html << %{<p>NOT FOUND: Unable to find the team member with ID: #{params[:id]}</p>}
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    status 404 # Not Found
    content_type 'text/html'
    body(html)
  else
    html = Array.new
    doc_html.each { |p| html << p }
    html << %{<h1>Team Resource - #{person.name}</h1>}
    html << %{<p>ID - #{person.id}</p>}
    html << %{<p>Name - #{person.name}</p>}
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    status 200 # OK
    content_type 'text/html'
    body(html)
  end
end

delete '/api/team/:id' do
  person = team[params[:id]]
  if person.nil? then
    html = Array.new
    html << %{<h1>Team Resource</h1>}
    html << %{<p>NOT FOUND: Unable to find the team member with ID: #{params[:id]}</p>}
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    status 404 # Not Found
    content_type 'text/html'
    body(html)
  else
    name = team[params[:id]].name
    team.delete(params[:id])
    html = Array.new
    html << %{<h1>Team Resource</h1>}
    html << %{<p>ACCEPTED: Deleted team member #{name} with ID #{params[:id]}</p>}#
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    status 202 # Accepted
    content_type 'text/html'
    body(html)
  end
end

post '/api/team/:id' do
  data = JSON.parse(request.body.string)
  if data.nil? or !data.has_key?('id') or !data.has_key?('name') then
    html = Array.new
    html << %{<h1>Team Resources</h1>}
    html << %{<p>BAD REQUEST: Unable to create the team member, insufficient data (missing id or name)</p>}
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    status 400 # Bad Request
    content_type 'text/html'
    body(html)
  else
    html = Array.new
    html << %{<h1>Team Resourcer</h1>}
    if team[data['id']] then
      html << %{<p>FORBIDDEN: Unable to create the team member, id #{data['id']} already exists</p>}
      html << %{<p><a href="/api/team/#{data['id']}">Go to see existing team member</a></p>}
      status 403 # Forbidden
    else
      person = Person.new(data['id'],data['name'])
      team[data['id']] = person
      html << %{<p>CREATED: id: #{person.id} name: #{person.name}</p>}

      status 201 # Created
    end
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    content_type 'text/html'
    body(html)
  end 
end

put '/api/team/:id' do
  data = JSON.parse(request.body.string)
  if data.nil? or !data.has_key?('id') or !data.has_key?('name') then
    html = Array.new
    html << %{<h1>Team Resources</h1>}
    html << %{<p>BAD REQUEST: Unable to update the team member, insufficient request data (missing id or name)</p>}
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    status 400 # Bad Request
    content_type 'text/html'
    body(html)
  else
    html = Array.new
    html << %{<h1>Team Resourcer</h1>}
    if !team[data['id']] then
      html << %{<p>NOT FOUND: Unable to update the team member, id #{data['id']} doesn't exist</p>}
      status 404 # Not Found
    else
      person = Person.new(data['id'],data['name'])
      team[data['id']] = person
      html << %{<p>ACCEPTED: Updated team member id #{person.id} to #{person.name}</p>}
      status 202 # Accepted
    end
    html << %{<p><a href="/api/team" rel="team">Team Resources</a></p>}
    request_html(request).each { |p| html << p }

    content_type 'text/html'
    body(html)
  end 
end

after do
  response['X-Api-Header'] = API_VERSION
end