sinatra-patterns

Sinatra Patterns Skill

Tier 1: Quick Reference

Common Routing Patterns

Basic Routes:

get '/' do
  'Hello World'
end

post '/users' do
  # Create user
end

put '/users/:id' do
  # Update user
end

delete '/users/:id' do
  # Delete user
end

Route Parameters:

# Named parameters
get '/users/:id' do
  User.find(params[:id])
end

# Parameter constraints
get '/users/:id', :id => /\d+/ do
  # Only matches numeric IDs
end

# Wildcard
get '/files/*.*' do
  # params['splat'] contains matched segments
end

Query Parameters:

get '/search' do
  query = params[:q]
  page = params[:page] || 1
  results = search(query, page: page)
end

Basic Middleware

# Session middleware
use Rack::Session::Cookie, secret: ENV['SESSION_SECRET']

# Security middleware
use Rack::Protection

# Logging
use Rack::CommonLogger

# Compression
use Rack::Deflater

Simple Error Handling

not_found do
  'Page not found'
end

error do
  'Internal server error'
end

error 401 do
  'Unauthorized'
end

Helpers

helpers do
  def logged_in?
    !session[:user_id].nil?
  end

  def current_user
    @current_user ||= User.find_by(id: session[:user_id])
  end
end

---

Tier 2: Detailed Instructions

Advanced Routing

Modular Applications:

# app/controllers/base_controller.rb
class BaseController < Sinatra::Base
  configure do
    set :views, Proc.new { File.join(root, '../views') }
    set :public_folder, Proc.new { File.join(root, '../public') }
  end

  helpers do
    def json_response(data, status = 200)
      content_type :json
      halt status, data.to_json
    end
  end
end

# app/controllers/users_controller.rb
class UsersController < BaseController
  get '/' do
    users = User.all
    json_response(users.map(&:to_hash))
  end

  get '/:id' do
    user = User.find(params[:id]) || halt(404)
    json_response(user.to_hash)
  end

  post '/' do
    user = User.create(params[:user])
    if user.persisted?
      json_response(user.to_hash, 201)
    else
      json_response({ errors: user.errors }, 422)
    end
  end
end

# config.ru
map '/users' do
  run UsersController
end