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AKIRA MATSUDA: So. Welcome to Ruby on Rails
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
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,
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
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
after

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

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

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actually gonna spend the whole forty minutes
just for

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reading the whole framework code.

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And, not gonna talk anything about, like,
science. But

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it's like, reading a novel, reading a story.
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,
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,
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
piece of

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code in your application, that means you don't
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
are

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filled with such magics like, for example,
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
inheriting from ActionController::Base? We.

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Or, how the http request actually calls this
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
variable. Et

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cetera, et cetera.

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Or, think about this example. This, this,
this is

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

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

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not an application reader, right. We, we're
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
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
second line. Looks like

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a method call taking a hash parameter. What
is

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it doing? Who actually knows, who here actually
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
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,
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
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
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
need

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to deal with them. With the bugs.

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So, naturally, Rails programmer job is not
just to

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maintain the application, but you also need
to maintain

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Rails framework as well. It's our job. And
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
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
hope

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you enjoy.

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Let's begin. This is what I'm gonna talk.
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
inside. So. I

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

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if you're a Ruby programmer, you just can
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
tiny

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tip. How you can find the GitHub repository
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
and

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how you can use it.

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

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does is after this gem installed, it will
automatically

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git, git clone this source from GitHub repository.
So,

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you, you need not to memorize the author's
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
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.
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
like

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

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right.

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And you can find these declarations. A bunch
of

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add_dependencies. So that means Rails has
no code inside,

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but instead if defines several dependencies.
It means that

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this is a meta, meta-gem, meta-package, to
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
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
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
ActionView. And this

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is something called model, and these are views,
and

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these are controllers.

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So, Rails gem is a meta-package that depends
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
Rails server,

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you just need to run Rails server command.
So,

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what's happening internally when you execute
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
read

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that file first. That file should look like
this.

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

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requires rails/commands.

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

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gonna skip the bundler part, because it's,
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
requires rails/commands.

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So where is "rails" directory? You can find
"rails"

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directory in the railties gem. There's a gem
called

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

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is about railties.

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What, what actually railties is? Railties
is a very

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wisely-crafted tiny library, initially created
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
is about

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Rails internals. And the gemspec shows that
now this

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gem includes some libraries. Ruby files. Actually,
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
and one

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file called rails dot rb.

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

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

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It requires commands_tasks, and then invokes
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
rb.

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

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

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very top, it requires rails. So, then jump
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
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,
and it defines a

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Rails Application class, inheriting Rails
Engine.

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

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it, Rails Engine class inherits from Rails
Railtie. So,

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next file is rails/railtie.

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

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

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Initializable. So next follow the, next file
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,
Railtie, Initializable. Which

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are very, very important. Actually, the core
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,
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.
And I have

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another answer for you. Railties is, according
to Wikipedia,

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this is the definition of something called
Railroad tie.

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It's a rectangular piece of wood which is
laid

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underneath the rails, sometimes called sleeper,
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
lies

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underneath the Rails framework. This is why
they named

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it railties, I guess. This is a beautiful
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,
and

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you can find some uses of railtie. These are

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in, not only in railties, they're actually,
these are

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in mailers, ActiveRecord, ActionPack, blah,
blah, blah.

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

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take a look at it, like this. So, each

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

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this. This is how we use railtie.

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So, railtie is not only in the core, but

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in, we can find railties everywhere. Railtie.
It's inside

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each component, right. And, so, this is what's
written

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inside the railtie class.

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It has some, mainly we, we see two kinds

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of class method calls, config and initializer,
right. These

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are class method calls to railtie class. So,
what's

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config?

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This is the definition. Railtie config create
something. Instantiates

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something like Railtie::Configuration. And
so config is a instance

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of Railtie::Configuration. Railtie::Configuration
is something like this. It, it

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has one method_missing method. And it accepts
any method

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call and just stores the given name and arguments

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and block into a class-level hash.

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So, what is initializer? Initializer looks
like this. The,

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it just keeps the given block as a proc

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instance, with a name, with a given name,
right.

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So, this is everything. This is what railties
is

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doing. It, it sets something, some values
via config

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method call and initializer method call. And
to, to

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use them for the later use.

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And railties is actually class, but it's prohibited
to

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instantiate. So, you cannot make a instance
of the

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railtie class. Instead, you just can inherit
and, when

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inherited, it, it kind of memorizes the, the
children

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class names.

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So, this is a summary what, of what railties

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is doing. Railties is a core of Rails that

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provides Railtie, Engine, Application, et
cetera, and we can

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find Railtie in other Rails components like
ActiveRecord, ActionPack.

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And a railtie can keep config and initializer
values.

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And Railtie ties up these railties, all right.

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So, let's see how, how actually Rails server
ties

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00:20:47,009 --> 00:20:53,999
these up. And how, how Rails server boots.
So,

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00:20:53,999 --> 00:20:58,169
let's go back to rails/commands/commands_tasks
dot rb. After it

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requiring rails/commands/server, it executes,
it requires the application and

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00:21:03,929 --> 00:21:07,340
then executes server dot start.

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Server dot start is defined here, because
it was

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00:21:15,909 --> 00:21:22,909
defined in Rails/commands/server. Server dot
start calls, just calls

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00:21:23,870 --> 00:21:28,470
super. And super is, super class of this class

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00:21:28,470 --> 00:21:30,669
is Rack::Server.

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00:21:30,669 --> 00:21:36,870
So, welcome to the Rack world. Now, now we

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00:21:36,870 --> 00:21:43,870
need to read the Rack code. Oh my god.

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00:21:48,330 --> 00:21:51,970
This is not Rack hacking guide, so I'm just

249
00:21:51,970 --> 00:21:58,970
gonna skip it. It. Anyway. Finally calls something
like

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00:22:04,019 --> 00:22:11,019
this, via rack/builder. It evaluates this
Ruby string. Like,

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00:22:16,610 --> 00:22:22,549
Rack::Builder dot new taking contents of config
dot ru

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00:22:22,549 --> 00:22:26,610
in your application.

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00:22:26,610 --> 00:22:33,610
And Rack::Builder just instance_evals the
given block. So, this

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00:22:35,110 --> 00:22:42,110
is what's written inside your application's
config dot ru.

255
00:22:43,940 --> 00:22:50,940
It requires config/environment dot rb first,
and runs Rails.application.

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00:22:52,299 --> 00:22:55,220
Run is also a Rack command, I mean, Rack

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00:22:55,220 --> 00:22:58,379
method.

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00:22:58,379 --> 00:23:05,379
So, I just, I just, like, explained very fast,

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00:23:07,519 --> 00:23:11,730
like, how the method, method call goes. How
method

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00:23:11,730 --> 00:23:15,409
call graph looks like. So, I guess you find

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00:23:15,409 --> 00:23:19,759
it difficult to follow, and how can it actually

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00:23:19,759 --> 00:23:24,090
follow these method, method call graphs?

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00:23:24,090 --> 00:23:30,929
Here's one tip. Just, puts caller from, in
a

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00:23:30,929 --> 00:23:35,019
file inside your application. For, example,
in config dot

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00:23:35,019 --> 00:23:39,919
ru file, like this. Just add a puts caller

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00:23:39,919 --> 00:23:44,299
here. And run Rails server. Then, you'll get
an

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00:23:44,299 --> 00:23:50,870
output like this in your console.

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00:23:50,870 --> 00:23:55,730
And these, these are basically what I explained.
Like,

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00:23:55,730 --> 00:24:02,730
we see commands/task and server and, like,
Rack::Builder.

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00:24:05,919 --> 00:24:12,210
So, this is very useful. Like, when you get

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00:24:12,210 --> 00:24:17,940
lost in the Ruby, Ruby jungle, use puts caller

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00:24:17,940 --> 00:24:22,869
in caller locations, and that'll show you
the path

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00:24:22,869 --> 00:24:25,690
to the place you are.

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00:24:25,690 --> 00:24:32,690
All right. Anybody, but. The config dot ru
file

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00:24:33,759 --> 00:24:39,039
requires config/environment.rb, and this is,
as you know, what's

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00:24:39,039 --> 00:24:44,679
written inside the config/environment.rb.
It requires config/application dot rb

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00:24:44,679 --> 00:24:47,610
and calls Rails.application.initialize!

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00:24:47,610 --> 00:24:54,610
So, Rails.application.initialize! is the very,
very important method. As

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00:24:57,809 --> 00:25:01,720
you may notice from, because it, it has an

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00:25:01,720 --> 00:25:08,720
exclamation mark. This is what's written in
application.rb. Since,

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00:25:09,220 --> 00:25:13,529
Rails 4 point 1, it, it really has nothing

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00:25:13,529 --> 00:25:16,970
in its, in its class.

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00:25:16,970 --> 00:25:23,970
But, but it defines a class called Application,
inheriting

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00:25:24,360 --> 00:25:31,360
from Rails::Application.

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00:25:33,499 --> 00:25:39,460
Before that, it requires rails/all and bundles
all the

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00:25:39,460 --> 00:25:45,330
bundled gems. So this is rails dot, rails/all
dot

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00:25:45,330 --> 00:25:51,759
rb. What it actually does is something like
this.

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00:25:51,759 --> 00:25:57,909
It defines, so, it requires all these railties
that

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00:25:57,909 --> 00:26:04,909
I showed you before. Railties defines configs
and initializers,

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00:26:06,330 --> 00:26:10,879
as we have seen already.

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00:26:10,879 --> 00:26:17,879
And then, we call Rails.application.initialize
exclamation. So, so we,

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00:26:22,039 --> 00:26:27,929
we define initializers here and load all initializers
and

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00:26:27,929 --> 00:26:33,049
then initialize exclamation, right.

294
00:26:33,049 --> 00:26:40,049
So, this is the initialize method. It run_initializers,
and

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00:26:41,559 --> 00:26:48,559
run_initializers, it calls run, run method
for, for each

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00:26:53,059 --> 00:26:59,830
initialize- initializable object in the initializers
collection.

297
00:26:59,830 --> 00:27:06,070
So initializable looks like this. Run just
executes the

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00:27:06,070 --> 00:27:13,070
given argument. I mean, instance_exec through
stored proc inside

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00:27:13,950 --> 00:27:20,950
the same context, right. I mean, in this case,

300
00:27:23,080 --> 00:27:27,119
at sign context is actually the application
instance, so

301
00:27:27,119 --> 00:27:34,119
it just instance_execs the stored procs in
the initializers.

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00:27:34,460 --> 00:27:38,190
In the application's context.

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00:27:38,190 --> 00:27:45,190
So, I said initializers collection. Initializers
collection is this.

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00:27:52,749 --> 00:27:59,749
And initializers, so, initializers, yeah.
In rai- railties initializers

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00:28:02,239 --> 00:28:07,860
was created like this. So, what, what's in
the

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00:28:07,860 --> 00:28:13,669
initializer's collection is instances of Rails
initializer, initializable initializer.

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00:28:13,669 --> 00:28:20,320
Which, each initializer just, just holds a
proc instance,

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00:28:20,320 --> 00:28:24,159
right.

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00:28:24,159 --> 00:28:27,269
And as we've seen already these are called
from

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00:28:27,269 --> 00:28:33,129
each Railtie classes.

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00:28:33,129 --> 00:28:40,129
So. This is, this is what initialize do. And,

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00:28:41,129 --> 00:28:45,659
so let's go back to the server. As we've

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00:28:45,659 --> 00:28:52,659
seen, the start method calls super. I'm sorry.
I'll

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00:28:52,730 --> 00:28:54,440
skip this.

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00:28:54,440 --> 00:29:01,440
So. Summary. So, this is what we, what the

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00:29:02,830 --> 00:29:08,210
railtie does for booting up the Rails server.
Finally,

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00:29:08,210 --> 00:29:13,669
it runs Rails::Application in config dot ru.
Do you

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00:29:13,669 --> 00:29:17,610
remember? It's written in config dot ru file.
Run.

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00:29:17,610 --> 00:29:20,340
Run the application.

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00:29:20,340 --> 00:29:26,539
So what is run? What is run method? It's

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00:29:26,539 --> 00:29:31,499
defined like this. And with this, with this
definition,

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00:29:31,499 --> 00:29:38,499
the Rack server calls Rails.application dot
call. Rails.application responds

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00:29:41,129 --> 00:29:44,789
to call. So you can call this. That means

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00:29:44,789 --> 00:29:47,850
Rails.application is a Rack application.

325
00:29:47,850 --> 00:29:54,489
And Rails.application as a Rack application,
it, it has

326
00:29:54,489 --> 00:29:58,759
a call method like this. It calls super. The

327
00:29:58,759 --> 00:30:05,759
super, the Rails.application super class was
Rails::Engine. So, so

328
00:30:07,429 --> 00:30:08,999
jump to Rails::Engine.

329
00:30:08,999 --> 00:30:15,999
Rails::Engine has this like call method. OK.
The call

330
00:30:16,080 --> 00:30:22,769
goes to app dot call. App is something like

331
00:30:22,769 --> 00:30:28,460
this. It's a config middleware that contains
default middleware

332
00:30:28,460 --> 00:30:35,460
stack, and the endpoint, something called
endpoint. Look at

333
00:30:36,039 --> 00:30:38,049
this.

334
00:30:38,049 --> 00:30:44,330
So, what's the end point? End point is a

335
00:30:44,330 --> 00:30:51,330
route. Route is a ActionDispatch::Routing::RouteSet
by default. OK.

336
00:30:56,169 --> 00:31:03,169
So. So, the next thing is routes. Route is

337
00:31:06,989 --> 00:31:13,989
usually defined in config/routes dot rb like
this. So,

338
00:31:14,379 --> 00:31:21,289
let's think of this simple route. Routes,
Rails.application.routes is,

339
00:31:21,289 --> 00:31:28,289
is ActionDispatch::Routing::RouteSet. It's
defined here in ActionDispatch gem, I'm

340
00:31:29,159 --> 00:31:33,749
sorry. ActionPack gem in action_dispatch directory.

341
00:31:33,749 --> 00:31:38,470
It, it also responds to call, as it's a

342
00:31:38,470 --> 00:31:45,470
Rack application. And call goes to router
dot call.

343
00:31:47,460 --> 00:31:54,460
Router is defined like this. Journey::Router.new.
So, so router

344
00:31:54,690 --> 00:31:57,059
is a Journey thing.

345
00:31:57,059 --> 00:32:04,059
Then, so Rails.application routes is also
a Rack application

346
00:32:14,080 --> 00:32:17,989
that defines endpoint, and it finally goes
to the

347
00:32:17,989 --> 00:32:20,679
Journey thing. But for now let's go back to

348
00:32:20,679 --> 00:32:25,590
the Routes.draw DSL.

349
00:32:25,590 --> 00:32:28,340
Here.

350
00:32:28,340 --> 00:32:35,340
So, routes.draw is defined like this. It just
evaluates

351
00:32:37,059 --> 00:32:44,059
the given block. In the ActionDispatch routing
mapper. So,

352
00:32:47,570 --> 00:32:54,519
this DSL actually calls ActionDispatch::Routing::Mapper#get
method, right. And get

353
00:32:54,519 --> 00:32:58,799
method is like this. It calls map_method.
map_method calls

354
00:32:58,799 --> 00:33:05,600
match. match calls decomposed_match, and decomposed_match
calls add_route.

355
00:33:05,600 --> 00:33:12,600
So, anyway. It finally goes to Mapper#add_route.
And Mapper

356
00:33:14,190 --> 00:33:21,190
add_route calls Mapping dot new route. And
add_route returns

357
00:33:24,330 --> 00:33:31,330
a, finally, it returns a Journey route. And
then,

358
00:33:31,879 --> 00:33:37,789
like, adds the given, sorry, the traded route
into

359
00:33:37,789 --> 00:33:42,649
the collection. Journey::Routes collection.

360
00:33:42,649 --> 00:33:49,649
So. So, this is what the Journey does. And,

361
00:33:51,059 --> 00:33:58,059
what's this? Yeah. It finally calls Mapper
to_route, Mapping#to_route,

362
00:33:58,609 --> 00:34:02,340
so to_route is defined like this.

363
00:34:02,340 --> 00:34:09,340
I'm just gonna skip this. It's, it just returns

364
00:34:11,379 --> 00:34:16,219
the given app parameter, which was the endpoint
given

365
00:34:16,219 --> 00:34:21,239
into the methods parameter. So it finally,
finally it,

366
00:34:21,239 --> 00:34:28,010
it returns endpoint. And endpoint is if, if
it

367
00:34:28,010 --> 00:34:32,679
responds_to call, just returns that. And if
not, call

368
00:34:32,679 --> 00:34:34,500
Dispatcher.

369
00:34:34,500 --> 00:34:41,500
So. So the, the. The hash value can, could

370
00:34:45,239 --> 00:34:49,750
be respond_to call, for example, like this.
Or mounted

371
00:34:49,750 --> 00:34:53,659
engine, for example. But usually it doesn't
respond to

372
00:34:53,659 --> 00:35:00,660
call, so it calls dispatcher. Dispatcher is
a Routing::RouteSet::Dispatcher.

373
00:35:04,940 --> 00:35:08,080
And Dispatcher is also a Rack app, so it

374
00:35:08,080 --> 00:35:12,190
can be called. And the call the Dispatcher
goes

375
00:35:12,190 --> 00:35:16,900
to, dispatch method.

376
00:35:16,900 --> 00:35:23,900
Dispatch, so, it finally goes at the bottom
line.

377
00:35:25,030 --> 00:35:28,470
It finally goes to controller dot action with
a

378
00:35:28,470 --> 00:35:35,470
given action name, dot call. So, so finally,
what,

379
00:35:36,970 --> 00:35:42,730
what the router finally calls is this. FooController
dot

380
00:35:42,730 --> 00:35:49,730
action method with a given action, action
name. And

381
00:35:50,280 --> 00:35:52,830
it returns something callable.

382
00:35:52,830 --> 00:35:58,790
So, this is the route DSL. get "/hello" =>

383
00:35:58,790 --> 00:36:05,790
"foo#bar" maps to FooController dot action('bar').

384
00:36:10,760 --> 00:36:15,090
This is about Journey. And I think I have

385
00:36:15,090 --> 00:36:17,150
no time, so I'm gonna skip this. I'm gonna

386
00:36:17,150 --> 00:36:22,200
skip this long Journey. Anyway, it resolves
the route.

387
00:36:22,200 --> 00:36:26,610
So, this is a summary. The, the main point

388
00:36:26,610 --> 00:36:29,800
is that 'foo#bar' becomes a Rack application
generated by

389
00:36:29,800 --> 00:36:33,740
FooController dot action('bar').

390
00:36:33,740 --> 00:36:39,870
So, the final chapter. Controllers and actions.
This, what's

391
00:36:39,870 --> 00:36:42,770
gonna happen when the server got a request?
It,

392
00:36:42,770 --> 00:36:49,770
it, it just calls this. So what is this?

393
00:36:50,500 --> 00:36:57,500
Firstly, the action method is defined like
this. It's,

394
00:37:00,730 --> 00:37:06,140
it calls the new dot dispatch inside the block.

395
00:37:06,140 --> 00:37:09,260
New, new means Controller dot new.

396
00:37:09,260 --> 00:37:16,260
So, dispatch, dispatch method creates set,
call set_response! and

397
00:37:16,430 --> 00:37:20,310
then calls super. So, what this dispatch method
does

398
00:37:20,310 --> 00:37:27,310
is creates Rails response object. And then
dispatch method,

399
00:37:29,720 --> 00:37:34,320
then creates request object. Whoops.

400
00:37:34,320 --> 00:37:39,990
All right. It sets the request object into
the

401
00:37:39,990 --> 00:37:46,990
instance. And then calls process method. Dispatch
finally calls

402
00:37:47,730 --> 00:37:53,940
ActionController::Metal#process. So, this
is what's written inside the process

403
00:37:53,940 --> 00:37:58,590
method. process method calls process_action,
and process_action calls send_action,

404
00:37:58,590 --> 00:38:05,590
and send_action is aliased to send. Ruby's
send method,

405
00:38:07,140 --> 00:38:09,130
right.

406
00:38:09,130 --> 00:38:16,130
So, FooController dot action('bar') creates
the Rails Request and

407
00:38:17,140 --> 00:38:21,780
Response objects into the controller instance.
Then, it just

408
00:38:21,780 --> 00:38:25,370
calls, calls the method name bar via Ruby
send

409
00:38:25,370 --> 00:38:28,810
method, OK.

410
00:38:28,810 --> 00:38:34,240
So, it can be like, FooController dot new,
with

411
00:38:34,240 --> 00:38:38,400
something, dot bar. It's a very simple Ruby
method

412
00:38:38,400 --> 00:38:43,080
call, finally. So, this is what's happening
inside the

413
00:38:43,080 --> 00:38:50,080
HTTP request. When the Rails server accepts
the HTTP

414
00:38:51,980 --> 00:38:57,360
request, it, it kind of, the Journey kind
of,

415
00:38:57,360 --> 00:39:02,060
somehow, resolves the results, and finally
calls this simple

416
00:39:02,060 --> 00:39:06,430
Ruby method. OK?

417
00:39:06,430 --> 00:39:10,530
And I guess it's, yeah. I guess it's time.

418
00:39:10,530 --> 00:39:17,530
I have thirty, thirty seconds left. So.

419
00:39:18,840 --> 00:39:24,270
Obviously there's more and more and more topics
about

420
00:39:24,270 --> 00:39:29,220
Rails internals, but unfortunately I had,
I just had

421
00:39:29,220 --> 00:39:32,090
forty minutes. Forty minutes was not enough
to talk

422
00:39:32,090 --> 00:39:37,740
about, like, ActiveRecord internals or helpers
or ActionPack, ActionController

423
00:39:37,740 --> 00:39:40,940
- these things.

424
00:39:40,940 --> 00:39:44,920
So, this is the end of my talk. But

425
00:39:44,920 --> 00:39:49,930
I'm kind of planning to write a book titled

426
00:39:49,930 --> 00:39:56,930
Ruby on Rails Hacking Guide. So, so hopefully.
I'm

427
00:39:57,580 --> 00:39:59,810
planning to write it in Japanese first and
then

428
00:39:59,810 --> 00:40:03,760
translate it into English later. So, hopefully
can find

429
00:40:03,760 --> 00:40:07,330
it, like, next year, maybe.

430
00:40:07,330 --> 00:40:12,900
And, yeah. I'll write everything in that book.
So

431
00:40:12,900 --> 00:40:19,900
please wait until the book is coming. Thank
you

432
00:40:19,900 --> 00:40:21,140
very much.