0:00:18.560,0:00:23.780
AKIRA MATSUDA: So. Welcome to Ruby on Rails[br]internal talk.

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This is titled Ruby on Rails Hacking Guide,

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which is deeply inspired by Minero Alki's[br]Legendary Ruby

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book titles Rails- for, Ruby Hacking Guide.

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So, before I get started, let me just introduce

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myself. I am Akira Matsuda - amatsuda on GitHub

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and Twitter. I'm a committer of Ruby and Ruby

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on Rails projects and I'm from Japan.

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As a individual on GitHub, I created a pagination

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library called kaminari and active_decoractor,[br]action_args and et cetera,

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et cetera. Such libraries.

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As a Rails committer, ranked in here, in the

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bottom, like, twenty-seventh. I've done 374[br]commits so far

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and, since I made my first commit about six

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years ago.

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I initially titled this talk as Ruby on Rails

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Hacking Guide, but I slightly changed my mind[br]after

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I listened to DHH's keynote. This talk should[br]be

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titled like Ruby on Rails Reading Guide. Since[br]we're

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actually gonna spend the whole forty minutes[br]just for

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reading the whole framework code.

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And, not gonna talk anything about, like,[br]science. But

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it's like, reading a novel, reading a story.[br]So,

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why should we, why should we read Rails? I

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think we have three big reasons here.

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Firstly, as DHH defined, we're software writers,[br]and you

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need to read a lot in order to be

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a good writer, right. This is obvious. So,[br]we

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need to read Rails to be a good Rails

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programmer. And if you don't understand any[br]piece of

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code in your application, that means you don't[br]really

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understand your application.

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So, don't let a magical piece of code exist

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in your app. I know that Rails applications[br]are

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filled with such magics like, for example,[br]like this.

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It's such simple, just one line of Ruby code,

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in just one method. But it, it really does

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a lot of things for you, right. But we

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need to be able to explain why, why is

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this controller inheriting from ApplicationController[br]inheriting from ActionController::Base? We.

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Or, how the http request actually calls this[br]in

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index Ruby method. Or why are we setting this

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u- users relation into a controller instance[br]variable. Et

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cetera, et cetera.

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Or, think about this example. This, this,[br]this is

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a typical Rails-ish DSL. This reads good.[br]It's pretty

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straight forward for readers, as a documentation.[br]But, you're

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not an application reader, right. We, we're[br]application writer.

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So you have to write this. And as a

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writer, you don't, don't usually write when[br]you don't

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understand what it means, right.

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So, so a question. What, what, what is this

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Rails.application.routes.draw, or get in the[br]second line. Looks like

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a method call taking a hash parameter. What[br]is

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it doing? Who actually knows, who here actually[br]knows

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what's gonna happen with this code? Can explain?

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Right. So, if you think, if you think you

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can explain how this define a route, if, if

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you cannot explain. Sorry. If you cannot explain[br]that

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means for, it's just a magic. And that's why

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you're, you're in this room now, right. So,[br]you'll

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soon get to know what the get means.

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And as the third reason to read Rails code

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is because Rails.has_many :bugs. So, as I[br]told you,

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I patched a lot. And mostly I, I patch

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Rails because I hit bugs in my production[br]application.

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And I guess, you all have the same experience.

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I'm sure. Rails is basically buggy. And we[br]need

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to deal with them. With the bugs.

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So, naturally, Rails programmer job is not[br]just to

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maintain the application, but you also need[br]to maintain

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Rails framework as well. It's our job. And[br]it's

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your job. So we need to be familiar with

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the code base.

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And strangely, this talk is kind of categorized[br]as

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a novice talk. But, I'm not sure. I'm, I'm

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gonna talk about the Rails internal. So. I[br]hope

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you enjoy.

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Let's begin. This is what I'm gonna talk.[br]So,

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first of all, Ruby on Rails is a open-source

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software on GitHub. There's no C-extension[br]inside. So. I

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mean, there's, there's no C-code. 100% Ruby.[br]That means,

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if you're a Ruby programmer, you just can[br]read

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it and, and you can write it if necessary.

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You can get its source code here, by git

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cloning from GitHub. By the way, here's a[br]tiny

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tip. How you can find the GitHub repository[br]for

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the gem you use. You can use, you can

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use a gem named gem-src. It's on, it's here

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on GitHub. And please take a look at this

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repository. This is how you can install it[br]and

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how you can use it.

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I'm not gonna explain here. But. So, what[br]this

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does is after this gem installed, it will[br]automatically

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git, git clone this source from GitHub repository.[br]So,

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you, you need not to memorize the author's[br]name

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or you can not, you don't need to search

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on GitHub. As a gem install, it automatically[br]gets

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the code from GitHub. It's so useful for social

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coders.

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Anyway. Let's go back to the Rails source.[br]Firstly,

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let's see what's included in the gem. To know

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what's included in gem, take a look at the

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gemspec. So this is taken from the file rails.gemspec.

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Here it defines the files included. It looks[br]like

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it doesn't really include any program. It's[br]just documents,

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right.

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And you can find these declarations. A bunch[br]of

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add_dependencies. So that means Rails has[br]no code inside,

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but instead if defines several dependencies.[br]It means that

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this is a meta, meta-gem, meta-package, to[br]install these

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seven gems, right.

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And these seven gems are in the Rails repository.

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And Rails is a full-stack framework, a full-stack[br]MVC

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framework. And all these M and V and C

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are included in this one repository. So we[br]have

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model, view, and controller.

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And we have these gems. I'm sorry it's, can

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you read it? I'm sorry it's hard to read.

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Anyway. We have ActiveRecord, ActionPack and[br]ActionView. And this

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is something called model, and these are views,[br]and

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these are controllers.

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So, Rails gem is a meta-package that depends[br]on

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these seven gems.

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So let's take a look at the Rails server

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command and, and let me explain how, how the

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Rails actually boots. For, starting up the[br]Rails server,

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you just need to run Rails server command.[br]So,

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what's happening internally when you execute[br]this command?

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When I hit the Rails command it actually executes

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bin slash rails in your application. So, let's[br]read

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that file first. That file should look like[br]this.

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It requires config/boot inside your application[br]first, and then

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requires rails/commands.

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Rails/boot looks like this. It just bundles[br]something. I'm

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gonna skip the bundler part, because it's,[br]it's out

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of today's scope, but it, it, it kind of

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tweaks the $LOAD_PATH nicely.

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And so the second line. Rails/commands. It[br]requires rails/commands.

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So where is "rails" directory? You can find[br]"rails"

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directory in the railties gem. There's a gem[br]called

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railties, which I, I didn't explain. So, next[br]chapter

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is about railties.

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What, what actually railties is? Railties[br]is a very

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wisely-crafted tiny library, initially created[br]by Yehuda Katz and

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Carl, Carl Lerche. So let's dive into it.

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Here's the gemspec. The gemspec says this[br]is about

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Rails internals. And the gemspec shows that[br]now this

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gem includes some libraries. Ruby files. Actually,[br]it includes

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like this. So, when you step inside the railties

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lib directory, you'll see these. One directory[br]and one

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file called rails dot rb.

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So these's the rails directory. And this is[br]how

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Rails/commands dot rb looks like in the railties[br]gem.

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It requires commands_tasks, and then invokes[br]a CommandTask with

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a given command name. ARGV, right.

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In this case, so, in this case server, right.

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So this is the file named commands_tasks dot[br]rb.

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It requires rails/commands/server first. So[br]let's take a look

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at rails/commands/server. And this is rails/commands/server.[br]It requires, at

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very top, it requires rails. So, then jump[br]to

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rails dot rb. Rails dot rb was at the

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very top of the repository, right.

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So this is how rails dot rb looks like.

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It requires rails/application. So, let's go[br]to rails/application. And

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it defines a top-level module named Rails.

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So rails/application, it requires rails/engine,[br]and it defines a

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Rails Application class, inheriting Rails[br]Engine.

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So, jump to rails/engine. Now, rails/engine[br]requires rails/railtie and

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it, Rails Engine class inherits from Rails[br]Railtie. So,

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next file is rails/railtie.

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Railtie, it looks like this. It requires rails/initializable[br]and

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rails/configuration. And defines Rails Railtie[br]class, that includes Rails

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Initializable. So next follow the, next file[br]is rails/initializable.

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It defines a Rails Initizable- Initializer.

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So, what we learned so far is, railties defines

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these core classes, like Application, Engine,[br]Railtie, Initializable. Which

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are very, very important. Actually, the core[br]of Rails.

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So railties is like this. It's the core of

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Rails, in the middle.

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And we had something called Plugin as well,[br]but

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it was gone since Rails 4.

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So, let's skip it. So railties is a library

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providing something underneath the Rails Application.[br]And I have

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another answer for you. Railties is, according[br]to Wikipedia,

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this is the definition of something called[br]Railroad tie.

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It's a rectangular piece of wood which is[br]laid

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underneath the rails, sometimes called sleeper,[br]railway sleeper.

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So this is rail ties. Consider this. The applications

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are the trains that run on Rails, and railties,

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Rails is the framework, and railties is something[br]lies

0:16:46.420,0:16:50.510
underneath the Rails framework. This is why[br]they named

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it railties, I guess. This is a beautiful[br]metaphor,

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isn't it?

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So how does it work? Or, how can we

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use it? This is how, how, how it's work.

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We can git grep the whole railtie repository,[br]and

0:17:10.169,0:17:15.900
you can find some uses of railtie. These are

0:17:15.900,0:17:20.939
in, not only in railties, they're actually,[br]these are

0:17:20.939,0:17:25.339
in mailers, ActiveRecord, ActionPack, blah,[br]blah, blah.

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We're gonna take it. So, so let's take a,

0:17:30.379,0:17:34.820
take a look at it, like this. So, each

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component has its own railtie, inheriting[br]from Rails::Railtie, like

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this. This is how we use railtie.

0:17:43.250,0:17:48.690
So, railtie is not only in the core, but

0:17:48.690,0:17:55.690
in, we can find railties everywhere. Railtie.[br]It's inside

0:17:55.690,0:18:00.779
each component, right. And, so, this is what's[br]written

0:18:00.779,0:18:03.580
inside the railtie class.

0:18:03.580,0:18:06.179
It has some, mainly we, we see two kinds

0:18:06.179,0:18:13.179
of class method calls, config and initializer,[br]right. These

0:18:14.429,0:18:21.429
are class method calls to railtie class. So,[br]what's

0:18:22.799,0:18:24.299
config?

0:18:24.299,0:18:31.299
This is the definition. Railtie config create[br]something. Instantiates

0:18:31.679,0:18:38.679
something like Railtie::Configuration. And[br]so config is a instance

0:18:41.639,0:18:47.070
of Railtie::Configuration. Railtie::Configuration[br]is something like this. It, it

0:18:47.070,0:18:52.220
has one method_missing method. And it accepts[br]any method

0:18:52.220,0:18:55.860
call and just stores the given name and arguments

0:18:55.860,0:19:02.570
and block into a class-level hash.

0:19:02.570,0:19:09.570
So, what is initializer? Initializer looks[br]like this. The,

0:19:10.590,0:19:15.600
it just keeps the given block as a proc

0:19:15.600,0:19:22.600
instance, with a name, with a given name,[br]right.

0:19:26.389,0:19:32.610
So, this is everything. This is what railties[br]is

0:19:32.610,0:19:38.019
doing. It, it sets something, some values[br]via config

0:19:38.019,0:19:42.950
method call and initializer method call. And[br]to, to

0:19:42.950,0:19:49.950
use them for the later use.

0:19:51.299,0:19:54.370
And railties is actually class, but it's prohibited[br]to

0:19:54.370,0:19:59.610
instantiate. So, you cannot make a instance[br]of the

0:19:59.610,0:20:06.610
railtie class. Instead, you just can inherit[br]and, when

0:20:07.809,0:20:13.960
inherited, it, it kind of memorizes the, the[br]children

0:20:13.960,0:20:17.889
class names.

0:20:17.889,0:20:24.759
So, this is a summary what, of what railties

0:20:24.759,0:20:27.759
is doing. Railties is a core of Rails that

0:20:27.759,0:20:30.779
provides Railtie, Engine, Application, et[br]cetera, and we can

0:20:30.779,0:20:34.870
find Railtie in other Rails components like[br]ActiveRecord, ActionPack.

0:20:34.870,0:20:38.580
And a railtie can keep config and initializer[br]values.

0:20:38.580,0:20:43.499
And Railtie ties up these railties, all right.

0:20:43.499,0:20:47.009
So, let's see how, how actually Rails server[br]ties

0:20:47.009,0:20:53.999
these up. And how, how Rails server boots.[br]So,

0:20:53.999,0:20:58.169
let's go back to rails/commands/commands_tasks[br]dot rb. After it

0:20:58.169,0:21:03.929
requiring rails/commands/server, it executes,[br]it requires the application and

0:21:03.929,0:21:07.340
then executes server dot start.

0:21:07.340,0:21:14.340
Server dot start is defined here, because[br]it was

0:21:15.909,0:21:22.909
defined in Rails/commands/server. Server dot[br]start calls, just calls

0:21:23.870,0:21:28.470
super. And super is, super class of this class

0:21:28.470,0:21:30.669
is Rack::Server.

0:21:30.669,0:21:36.870
So, welcome to the Rack world. Now, now we

0:21:36.870,0:21:43.870
need to read the Rack code. Oh my god.

0:21:48.330,0:21:51.970
This is not Rack hacking guide, so I'm just

0:21:51.970,0:21:58.970
gonna skip it. It. Anyway. Finally calls something[br]like

0:22:04.019,0:22:11.019
this, via rack/builder. It evaluates this[br]Ruby string. Like,

0:22:16.610,0:22:22.549
Rack::Builder dot new taking contents of config[br]dot ru

0:22:22.549,0:22:26.610
in your application.

0:22:26.610,0:22:33.610
And Rack::Builder just instance_evals the[br]given block. So, this

0:22:35.110,0:22:42.110
is what's written inside your application's[br]config dot ru.

0:22:43.940,0:22:50.940
It requires config/environment dot rb first,[br]and runs Rails.application.

0:22:52.299,0:22:55.220
Run is also a Rack command, I mean, Rack

0:22:55.220,0:22:58.379
method.

0:22:58.379,0:23:05.379
So, I just, I just, like, explained very fast,

0:23:07.519,0:23:11.730
like, how the method, method call goes. How[br]method

0:23:11.730,0:23:15.409
call graph looks like. So, I guess you find

0:23:15.409,0:23:19.759
it difficult to follow, and how can it actually

0:23:19.759,0:23:24.090
follow these method, method call graphs?

0:23:24.090,0:23:30.929
Here's one tip. Just, puts caller from, in[br]a

0:23:30.929,0:23:35.019
file inside your application. For, example,[br]in config dot

0:23:35.019,0:23:39.919
ru file, like this. Just add a puts caller

0:23:39.919,0:23:44.299
here. And run Rails server. Then, you'll get[br]an

0:23:44.299,0:23:50.870
output like this in your console.

0:23:50.870,0:23:55.730
And these, these are basically what I explained.[br]Like,

0:23:55.730,0:24:02.730
we see commands/task and server and, like,[br]Rack::Builder.

0:24:05.919,0:24:12.210
So, this is very useful. Like, when you get

0:24:12.210,0:24:17.940
lost in the Ruby, Ruby jungle, use puts caller

0:24:17.940,0:24:22.869
in caller locations, and that'll show you[br]the path

0:24:22.869,0:24:25.690
to the place you are.

0:24:25.690,0:24:32.690
All right. Anybody, but. The config dot ru[br]file

0:24:33.759,0:24:39.039
requires config/environment.rb, and this is,[br]as you know, what's

0:24:39.039,0:24:44.679
written inside the config/environment.rb.[br]It requires config/application dot rb

0:24:44.679,0:24:47.610
and calls Rails.application.initialize!

0:24:47.610,0:24:54.610
So, Rails.application.initialize! is the very,[br]very important method. As

0:24:57.809,0:25:01.720
you may notice from, because it, it has an

0:25:01.720,0:25:08.720
exclamation mark. This is what's written in[br]application.rb. Since,

0:25:09.220,0:25:13.529
Rails 4 point 1, it, it really has nothing

0:25:13.529,0:25:16.970
in its, in its class.

0:25:16.970,0:25:23.970
But, but it defines a class called Application,[br]inheriting

0:25:24.360,0:25:31.360
from Rails::Application.

0:25:33.499,0:25:39.460
Before that, it requires rails/all and bundles[br]all the

0:25:39.460,0:25:45.330
bundled gems. So this is rails dot, rails/all[br]dot

0:25:45.330,0:25:51.759
rb. What it actually does is something like[br]this.

0:25:51.759,0:25:57.909
It defines, so, it requires all these railties[br]that

0:25:57.909,0:26:04.909
I showed you before. Railties defines configs[br]and initializers,

0:26:06.330,0:26:10.879
as we have seen already.

0:26:10.879,0:26:17.879
And then, we call Rails.application.initialize[br]exclamation. So, so we,

0:26:22.039,0:26:27.929
we define initializers here and load all initializers[br]and

0:26:27.929,0:26:33.049
then initialize exclamation, right.

0:26:33.049,0:26:40.049
So, this is the initialize method. It run_initializers,[br]and

0:26:41.559,0:26:48.559
run_initializers, it calls run, run method[br]for, for each

0:26:53.059,0:26:59.830
initialize- initializable object in the initializers[br]collection.

0:26:59.830,0:27:06.070
So initializable looks like this. Run just[br]executes the

0:27:06.070,0:27:13.070
given argument. I mean, instance_exec through[br]stored proc inside

0:27:13.950,0:27:20.950
the same context, right. I mean, in this case,

0:27:23.080,0:27:27.119
at sign context is actually the application[br]instance, so

0:27:27.119,0:27:34.119
it just instance_execs the stored procs in[br]the initializers.

0:27:34.460,0:27:38.190
In the application's context.

0:27:38.190,0:27:45.190
So, I said initializers collection. Initializers[br]collection is this.

0:27:52.749,0:27:59.749
And initializers, so, initializers, yeah.[br]In rai- railties initializers

0:28:02.239,0:28:07.860
was created like this. So, what, what's in[br]the

0:28:07.860,0:28:13.669
initializer's collection is instances of Rails[br]initializer, initializable initializer.

0:28:13.669,0:28:20.320
Which, each initializer just, just holds a[br]proc instance,

0:28:20.320,0:28:24.159
right.

0:28:24.159,0:28:27.269
And as we've seen already these are called[br]from

0:28:27.269,0:28:33.129
each Railtie classes.

0:28:33.129,0:28:40.129
So. This is, this is what initialize do. And,

0:28:41.129,0:28:45.659
so let's go back to the server. As we've

0:28:45.659,0:28:52.659
seen, the start method calls super. I'm sorry.[br]I'll

0:28:52.730,0:28:54.440
skip this.

0:28:54.440,0:29:01.440
So. Summary. So, this is what we, what the

0:29:02.830,0:29:08.210
railtie does for booting up the Rails server.[br]Finally,

0:29:08.210,0:29:13.669
it runs Rails::Application in config dot ru.[br]Do you

0:29:13.669,0:29:17.610
remember? It's written in config dot ru file.[br]Run.

0:29:17.610,0:29:20.340
Run the application.

0:29:20.340,0:29:26.539
So what is run? What is run method? It's

0:29:26.539,0:29:31.499
defined like this. And with this, with this[br]definition,

0:29:31.499,0:29:38.499
the Rack server calls Rails.application dot[br]call. Rails.application responds

0:29:41.129,0:29:44.789
to call. So you can call this. That means

0:29:44.789,0:29:47.850
Rails.application is a Rack application.

0:29:47.850,0:29:54.489
And Rails.application as a Rack application,[br]it, it has

0:29:54.489,0:29:58.759
a call method like this. It calls super. The

0:29:58.759,0:30:05.759
super, the Rails.application super class was[br]Rails::Engine. So, so

0:30:07.429,0:30:08.999
jump to Rails::Engine.

0:30:08.999,0:30:15.999
Rails::Engine has this like call method. OK.[br]The call

0:30:16.080,0:30:22.769
goes to app dot call. App is something like

0:30:22.769,0:30:28.460
this. It's a config middleware that contains[br]default middleware

0:30:28.460,0:30:35.460
stack, and the endpoint, something called[br]endpoint. Look at

0:30:36.039,0:30:38.049
this.

0:30:38.049,0:30:44.330
So, what's the end point? End point is a

0:30:44.330,0:30:51.330
route. Route is a ActionDispatch::Routing::RouteSet[br]by default. OK.

0:30:56.169,0:31:03.169
So. So, the next thing is routes. Route is

0:31:06.989,0:31:13.989
usually defined in config/routes dot rb like[br]this. So,

0:31:14.379,0:31:21.289
let's think of this simple route. Routes,[br]Rails.application.routes is,

0:31:21.289,0:31:28.289
is ActionDispatch::Routing::RouteSet. It's[br]defined here in ActionDispatch gem, I'm

0:31:29.159,0:31:33.749
sorry. ActionPack gem in action_dispatch directory.

0:31:33.749,0:31:38.470
It, it also responds to call, as it's a

0:31:38.470,0:31:45.470
Rack application. And call goes to router[br]dot call.

0:31:47.460,0:31:54.460
Router is defined like this. Journey::Router.new.[br]So, so router

0:31:54.690,0:31:57.059
is a Journey thing.

0:31:57.059,0:32:04.059
Then, so Rails.application routes is also[br]a Rack application

0:32:14.080,0:32:17.989
that defines endpoint, and it finally goes[br]to the

0:32:17.989,0:32:20.679
Journey thing. But for now let's go back to

0:32:20.679,0:32:25.590
the Routes.draw DSL.

0:32:25.590,0:32:28.340
Here.

0:32:28.340,0:32:35.340
So, routes.draw is defined like this. It just[br]evaluates

0:32:37.059,0:32:44.059
the given block. In the ActionDispatch routing[br]mapper. So,

0:32:47.570,0:32:54.519
this DSL actually calls ActionDispatch::Routing::Mapper#get[br]method, right. And get

0:32:54.519,0:32:58.799
method is like this. It calls map_method.[br]map_method calls

0:32:58.799,0:33:05.600
match. match calls decomposed_match, and decomposed_match[br]calls add_route.

0:33:05.600,0:33:12.600
So, anyway. It finally goes to Mapper#add_route.[br]And Mapper

0:33:14.190,0:33:21.190
add_route calls Mapping dot new route. And[br]add_route returns

0:33:24.330,0:33:31.330
a, finally, it returns a Journey route. And[br]then,

0:33:31.879,0:33:37.789
like, adds the given, sorry, the traded route[br]into

0:33:37.789,0:33:42.649
the collection. Journey::Routes collection.

0:33:42.649,0:33:49.649
So. So, this is what the Journey does. And,

0:33:51.059,0:33:58.059
what's this? Yeah. It finally calls Mapper[br]to_route, Mapping#to_route,

0:33:58.609,0:34:02.340
so to_route is defined like this.

0:34:02.340,0:34:09.340
I'm just gonna skip this. It's, it just returns

0:34:11.379,0:34:16.219
the given app parameter, which was the endpoint[br]given

0:34:16.219,0:34:21.239
into the methods parameter. So it finally,[br]finally it,

0:34:21.239,0:34:28.010
it returns endpoint. And endpoint is if, if[br]it

0:34:28.010,0:34:32.679
responds_to call, just returns that. And if[br]not, call

0:34:32.679,0:34:34.500
Dispatcher.

0:34:34.500,0:34:41.500
So. So the, the. The hash value can, could

0:34:45.239,0:34:49.750
be respond_to call, for example, like this.[br]Or mounted

0:34:49.750,0:34:53.659
engine, for example. But usually it doesn't[br]respond to

0:34:53.659,0:35:00.660
call, so it calls dispatcher. Dispatcher is[br]a Routing::RouteSet::Dispatcher.

0:35:04.940,0:35:08.080
And Dispatcher is also a Rack app, so it

0:35:08.080,0:35:12.190
can be called. And the call the Dispatcher[br]goes

0:35:12.190,0:35:16.900
to, dispatch method.

0:35:16.900,0:35:23.900
Dispatch, so, it finally goes at the bottom[br]line.

0:35:25.030,0:35:28.470
It finally goes to controller dot action with[br]a

0:35:28.470,0:35:35.470
given action name, dot call. So, so finally,[br]what,

0:35:36.970,0:35:42.730
what the router finally calls is this. FooController[br]dot

0:35:42.730,0:35:49.730
action method with a given action, action[br]name. And

0:35:50.280,0:35:52.830
it returns something callable.

0:35:52.830,0:35:58.790
So, this is the route DSL. get "/hello" =>

0:35:58.790,0:36:05.790
"foo#bar" maps to FooController dot action('bar').

0:36:10.760,0:36:15.090
This is about Journey. And I think I have

0:36:15.090,0:36:17.150
no time, so I'm gonna skip this. I'm gonna

0:36:17.150,0:36:22.200
skip this long Journey. Anyway, it resolves[br]the route.

0:36:22.200,0:36:26.610
So, this is a summary. The, the main point

0:36:26.610,0:36:29.800
is that 'foo#bar' becomes a Rack application[br]generated by

0:36:29.800,0:36:33.740
FooController dot action('bar').

0:36:33.740,0:36:39.870
So, the final chapter. Controllers and actions.[br]This, what's

0:36:39.870,0:36:42.770
gonna happen when the server got a request?[br]It,

0:36:42.770,0:36:49.770
it, it just calls this. So what is this?

0:36:50.500,0:36:57.500
Firstly, the action method is defined like[br]this. It's,

0:37:00.730,0:37:06.140
it calls the new dot dispatch inside the block.

0:37:06.140,0:37:09.260
New, new means Controller dot new.

0:37:09.260,0:37:16.260
So, dispatch, dispatch method creates set,[br]call set_response! and

0:37:16.430,0:37:20.310
then calls super. So, what this dispatch method[br]does

0:37:20.310,0:37:27.310
is creates Rails response object. And then[br]dispatch method,

0:37:29.720,0:37:34.320
then creates request object. Whoops.

0:37:34.320,0:37:39.990
All right. It sets the request object into[br]the

0:37:39.990,0:37:46.990
instance. And then calls process method. Dispatch[br]finally calls

0:37:47.730,0:37:53.940
ActionController::Metal#process. So, this[br]is what's written inside the process

0:37:53.940,0:37:58.590
method. process method calls process_action,[br]and process_action calls send_action,

0:37:58.590,0:38:05.590
and send_action is aliased to send. Ruby's[br]send method,

0:38:07.140,0:38:09.130
right.

0:38:09.130,0:38:16.130
So, FooController dot action('bar') creates[br]the Rails Request and

0:38:17.140,0:38:21.780
Response objects into the controller instance.[br]Then, it just

0:38:21.780,0:38:25.370
calls, calls the method name bar via Ruby[br]send

0:38:25.370,0:38:28.810
method, OK.

0:38:28.810,0:38:34.240
So, it can be like, FooController dot new,[br]with

0:38:34.240,0:38:38.400
something, dot bar. It's a very simple Ruby[br]method

0:38:38.400,0:38:43.080
call, finally. So, this is what's happening[br]inside the

0:38:43.080,0:38:50.080
HTTP request. When the Rails server accepts[br]the HTTP

0:38:51.980,0:38:57.360
request, it, it kind of, the Journey kind[br]of,

0:38:57.360,0:39:02.060
somehow, resolves the results, and finally[br]calls this simple

0:39:02.060,0:39:06.430
Ruby method. OK?

0:39:06.430,0:39:10.530
And I guess it's, yeah. I guess it's time.

0:39:10.530,0:39:17.530
I have thirty, thirty seconds left. So.

0:39:18.840,0:39:24.270
Obviously there's more and more and more topics[br]about

0:39:24.270,0:39:29.220
Rails internals, but unfortunately I had,[br]I just had

0:39:29.220,0:39:32.090
forty minutes. Forty minutes was not enough[br]to talk

0:39:32.090,0:39:37.740
about, like, ActiveRecord internals or helpers[br]or ActionPack, ActionController

0:39:37.740,0:39:40.940
- these things.

0:39:40.940,0:39:44.920
So, this is the end of my talk. But

0:39:44.920,0:39:49.930
I'm kind of planning to write a book titled

0:39:49.930,0:39:56.930
Ruby on Rails Hacking Guide. So, so hopefully.[br]I'm

0:39:57.580,0:39:59.810
planning to write it in Japanese first and[br]then

0:39:59.810,0:40:03.760
translate it into English later. So, hopefully[br]can find

0:40:03.760,0:40:07.330
it, like, next year, maybe.

0:40:07.330,0:40:12.900
And, yeah. I'll write everything in that book.[br]So

0:40:12.900,0:40:19.900
please wait until the book is coming. Thank[br]you

0:40:19.900,0:40:21.140
very much.