├── README.md
├── app
    ├── controllers
    │   └── posts_controller.rb
    └── views
    │   └── posts
    │       ├── index.html.erb
    │       └── show.html.erb
├── config
    └── routes.rb
├── database.yml
├── internal
    ├── fake_rails.rb
    └── fake_rails
    │   ├── application.rb
    │   ├── controller.rb
    │   ├── dispatcher.rb
    │   └── routes.rb
└── server.rb


/README.md:
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 1 | Just having fun trying to recreate basic Rails functionality with pure ruby, no gems.
 2 | 
 3 | Inspiration and a lot of code in this repository comes from @OngMaple's amazing talk on Building web apps with Ruby Standard Library, at Euruko 2021 (https://www.youtube.com/watch?v=lxczDssLYKA) and @pedrogaspar's follow up on creating a TCP chat server (https://twitter.com/pedrogaspar/status/1398798494169772032).
 4 | 
 5 | To start the server, simply run `ruby server.rb`.
 6 | 
 7 | **Index page**
 8 | 
 9 | ![Screen Shot 2021-05-30 at 11 29 01 AM](https://user-images.githubusercontent.com/23641464/120110123-50099000-c13a-11eb-9b3d-bc5f28ebd18f.png)
10 | 
11 | **Show page**
12 | 
13 | ![Screen Shot 2021-05-30 at 11 28 27 AM](https://user-images.githubusercontent.com/23641464/120110126-53048080-c13a-11eb-8298-a762d7d02d96.png)
14 | 


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/app/controllers/posts_controller.rb:
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 1 | require "./internal/fake_rails/controller.rb"
 2 | 
 3 | class PostsController < FakeRails::Controller
 4 |   def index
 5 |     @posts = database.transaction { database[:posts] }
 6 | 
 7 |     @posts = @posts.map {|p| OpenStruct.new(p)}
 8 |   end
 9 | 
10 |   def show
11 |     @post = database.transaction { OpenStruct.new(database[:posts][params[:id].to_i]) }
12 |   end
13 | end
14 | 


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/app/views/posts/index.html.erb:
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1 | <h1>Posts</h1>
2 | <% @posts.each do |post| %>
3 |   <div>
4 |     <h2><%= post.title %></h2>
5 |     <p><%= post.content %></p>
6 |   </div>
7 | <% end %>
8 | 


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/app/views/posts/show.html.erb:
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1 | <h1><%= @post.title %></h1>
2 | <p><%= @post.content %></p>
3 | 


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/config/routes.rb:
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1 | FakeRails.application.routes.draw do
2 |   resources :posts
3 | end
4 | 


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/database.yml:
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1 | ---
2 | :posts:
3 | - :title: Amazing title
4 |   :content: Here's the content
5 | - :title: second post
6 |   :content: Another content!
7 | 


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/internal/fake_rails.rb:
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 1 | require "socket"
 2 | require "uri"
 3 | require "yaml/store"
 4 | require "erb"
 5 | require "ostruct"
 6 | 
 7 | require "./internal/fake_rails/dispatcher.rb"
 8 | require "./internal/fake_rails/application.rb"
 9 | require "./internal/fake_rails/routes.rb"
10 | require "./app/controllers/posts_controller.rb"
11 | 
12 | module FakeRails
13 |   def self.application
14 |     @application ||= Application.new
15 |   end
16 | end
17 | 
18 | require "./config/routes.rb"
19 | 


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/internal/fake_rails/application.rb:
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 1 | module FakeRails
 2 |   class Application
 3 |     attr_accessor :routes
 4 | 
 5 |     def initialize
 6 |       @routes = Routes.new
 7 |     end
 8 |   end
 9 | end
10 | 


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/internal/fake_rails/controller.rb:
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 1 | module FakeRails
 2 |   class Controller
 3 |     attr_reader :database, :params
 4 | 
 5 |     def initialize(params:)
 6 |       @database = YAML::Store.new("database.yml")
 7 |       @params = params
 8 |     end
 9 | 
10 |     def get_binding
11 |       binding
12 |     end
13 |   end
14 | end
15 | 


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/internal/fake_rails/dispatcher.rb:
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 1 | require "./internal/fake_rails.rb"
 2 | 
 3 | module FakeRails
 4 |   class Dispatcher
 5 |     attr_accessor :params
 6 | 
 7 |     def initialize(request_line:)
 8 |       @request_line = request_line
 9 |       @params = {}
10 |     end
11 | 
12 |     def http_response
13 |       if current_path
14 |         status_code = "200 OK"
15 | 
16 |         controller = Kernel.const_get("#{controller_name.capitalize}Controller").new(params: params)
17 |         controller.send(controller_action)
18 | 
19 |         body = erb_view.result(controller.get_binding)
20 |       else
21 |         status_code = "404 NOT FOUND"
22 |         body = "<b>Didn't hit any endpoint</b>"
23 |       end
24 | 
25 |       puts status_code
26 | 
27 |       <<~MSG
28 |         HTTP/1.1 #{status_code}
29 |         Content-Type: text/html
30 |         location: /show/data
31 | 
32 |         #{body}
33 |       MSG
34 |     end
35 | 
36 |     private
37 | 
38 |     def controller_name
39 |       current_path[:controller_name]
40 |     end
41 | 
42 |     def controller_action
43 |       current_path[:controller_action]
44 |     end
45 | 
46 |     def current_path
47 |       return @current_path if @current_path
48 | 
49 |       @current_path = paths.find { |path| path[:method] == request_method && path[:url] == request_url_with_params }
50 |     end
51 | 
52 |     def paths
53 |       FakeRails.application.routes.paths
54 |     end
55 | 
56 |     def request_method
57 |       @request_line.split[0]
58 |     end
59 | 
60 |     def request_url_with_params
61 |       return @request_url_with_params if @request_url_with_params
62 | 
63 |       # update params to correctly match paths with keywords, ex. /posts/2 to /posts/:id
64 |       url_parts = request_url.split("/")
65 |       paths.each do |path|
66 |         path_url_parts = path[:url].split("/")
67 |         path_url_parts.each.with_index do |part, index|
68 |           if part.start_with?(":") && url_parts[index]
69 |             params[part.sub(":", "").to_sym] = url_parts[index]
70 |             url_parts[index] = part
71 |           end
72 |         end
73 |       end
74 | 
75 |       @request_url_with_params = url_parts.join("/")
76 |     end
77 | 
78 |     def request_url
79 |       @request_url ||= @request_line.split[1]
80 |     end
81 | 
82 |     def request_version_number
83 |       @request_line.split[2]
84 |     end
85 | 
86 |     def erb_view
87 |       file_content = File.read("./app/views/#{controller_name}/#{controller_action}.html.erb")
88 |       body = ERB.new(file_content)
89 |     end
90 |   end
91 | end
92 | 


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/internal/fake_rails/routes.rb:
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 1 | module FakeRails
 2 |   class Routes
 3 |     attr_accessor :paths
 4 | 
 5 |     def initialize
 6 |       @paths = []
 7 |     end
 8 | 
 9 |     def draw(&block)
10 |       instance_exec(&block)
11 |     end
12 | 
13 |     def resources(name)
14 |       @paths = [
15 |         {method: "GET", url: "/#{name}", controller_action: "index", controller_name: name},
16 |         {method: "GET", url: "/#{name}/:id", controller_action: "show", controller_name: name},
17 |         {method: "GET", url: "/#{name}/new", controller_action: "new", controller_name: name},
18 |       ]
19 |     end
20 |   end
21 | end
22 | 


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/server.rb:
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 1 | require "./internal/fake_rails.rb"
 2 | 
 3 | server = TCPServer.new(3000)
 4 | 
 5 | loop do
 6 |   client = server.accept
 7 | 
 8 |   request_line = client.readline
 9 | 
10 |   http_response = FakeRails::Dispatcher.new(request_line: request_line).http_response
11 | 
12 |   client.puts(http_response)
13 | 
14 |   client.close
15 | end
16 | 


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