WEBVTT

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Ok, here's the scoop.

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Wesley Crusher - everyone's favorite ensign
from Star Trek - has retired from Starfleet

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and is working with us to start a
new business: Wesley's Star Shop.

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Someone's gotta break the Ferengi monopoly
on the galaxy's starship repair business,

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and he's hired us to build the site to do that.

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We're about to give the Ferengi
a run for their latinum!

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And it starts with building our first page.

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The idea behind every page is always the same.

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Step one, give it a cool URL.

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That's called the route.

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Step two, write a PHP function
that generates the page.

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That's known as the controller.

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And that page could be HTML,
JSON, ASCII art, anything.

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In Symfony, the controller is
always a method inside a PHP class.

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So, we need to create our first PHP code!

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Where does PHP code live in our app?

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That's right, the src/ directory.

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Inside this src/Controller/
directory, create a new file.

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I would normally select new "PHP class", but
for this first time, create an empty file.

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We'll do each part by hand.

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Call it MainController.php, but you
can name this whatever you want.

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Inside, add the open PHP tag, and
then say class MainController.

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Above this, add a namespace of App\Controller.

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Okay, a few things about this.

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First, the fact that I put this class inside
a directory called Controller is optional.

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That's just a convention.

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You could rename this to
whatever the Klingon word

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for Controller is and everything
would the same...

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and probably be more interesting!

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However, there are a few rules
about PHP classes in general.

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The first is that every class must have
a namespace and that namespace needs

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to match your directory structure.

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It's always going to be App\ then
whatever directory you're inside.

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Without going into too much detail, that's
a rule you'll find in every PHP project.

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The second rule is that your class
name must match your filename .php.

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If you mess either of these up, you'll get an
error from PHP that it can't find your class.

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The Ferengi never make this mistake.

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Anyway, our goal is to create a controller,

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which is a method in a class
that builds the page.

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Add a new public function and call it homepage.

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But, again, the name doesn't matter.

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And... yea!

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It's not done yet, but this is our controller!

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But remember, a page is the
combination of a controller

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and a route, which defines the page's URL.

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Where do we put the route?

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Right above the controller method using
a feature of PHP called an attribute.

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Write #[] then start typing Route with a
capital R. Check out that auto-completion!

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Either option will work, but use the one from
Attribute - which is newer - then hit tab.

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When I did that, something
super important happened:

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my editor added a use statement
at the top of the class.

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Anytime you use a PHP attribute, you
must have a corresponding use statement

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for it in the same file.

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These attributes work almost like PHP
functions: you can pass a bunch of arguments.

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The first one is the path.

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Set this to /. Thanks to this, when
someone goes to the homepage - / -

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Symfony will call this controller
method to build the page!

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What... should our method return?

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Just the HTML we want, right?

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Or the JSON if we're building an API?

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Almost. The web works on a well-known system.

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First, a user requests a page.

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They say: Hey, I want to see /products...

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or I want to see /users.json.

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What we return back to them,
yes, contains HTML or JSON.

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But it's more than that.

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We also communicate back a status code -
which says whether the response was okay

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or had an error - as well as these things called
headers, which communicate a bit more info,

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like the format of what we're returning.

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This whole beautiful package
is called the response.

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So yeah, most of the time, we'll just be
thinking about returning HTML or JSON.

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But what we're truly sending is this
bigger, nerdier thing called a response.

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And so our entire job as web developers - no
matter what language we're programming in -

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is to understand the request from the
user, then create and return the response.

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And this brings us back to
something I love about Symfony.

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What does our controller return?

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A new Response object from Symfony!

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And again, PhpStorm wants to auto-complete this,
suggesting a few different Response classes.

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We want the one from the
Symfony HttpFoundation component.

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That's the Symfony library that contains
everything related to requests & responses.

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Hit tab. Once again, when we did that, PhpStorm
added a use statement at the top of the file.

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I'm going to use this trick constantly.

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Anytime you reference a class name, you
must have a corresponding use statement,

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else PHP will give you an error that
it can't find the Response class.

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Inside this, the first argument is
the content that we want to return.

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Start with a hardcoded string.

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Route, check!

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Controller that returns a Response, check!

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Let's try this.

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Back at the browser, this page was just a demo
that shows before we have a real homepage.

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Now that we do, when we refresh...

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there it is!

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I know it's not much yet, but we just learned
the first fundamental part of Symfony:

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that every page is a route & controller...

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and that every controller returns a response.

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Oh, and it's optional, but because our
controller always returns a Response,

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we can add a Response return type.

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That doesn't change how our code works,
but it makes it more descriptive to read.

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And if we ever did something silly and
returned something other than a response,

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PHP would give us a clear reminder.

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Next up: to supercharge our development, let's
install our first third-party package and learn

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about Symfony's amazing recipe system.