106 lines
4.4 KiB
Markdown
106 lines
4.4 KiB
Markdown
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# Hello, World
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Just about every framework ever written has some kind of hello world example included, so it'd be pretty rude of us to break this tradition!
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We'll start out by creating a very very basic hello world, and then we'll expand it to follow MVC principles.
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## Bare bones
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First off we have to make a controller that Kohana can use to handle a request.
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Create the file `application/classes/Controller/Hello.php` in your application folder and fill it out like so:
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<?php defined('SYSPATH') OR die('No Direct Script Access');
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Class Controller_Hello extends Controller
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{
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public function action_index()
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{
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echo 'hello, world!';
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}
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}
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Lets see what's going on here:
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`<?php defined('SYSPATH') OR die('No Direct Script Access');`
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: You should recognize the first tag as an opening php tag (if you don't you should probably [learn php](http://php.net)). What follows is a small check that makes sure that this file is being included by Kohana. It stops people from accessing files directly from the url.
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`Class Controller_Hello extends Controller`
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: This line declares our controller, each controller class has to be prefixed with `Controller_` and an underscore delimited path to the folder the controller is in (see [Conventions and styles](about.conventions) for more info). Each controller should also extend the base `Controller` class which provides a standard structure for controllers.
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`public function action_index()`
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: This defines the "index" action of our controller. Kohana will attempt to call this action if the user hasn't specified an action. (See [Routes, URLs and Links](tutorials.urls))
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`echo 'hello, world!';`
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: And this is the line which outputs the customary phrase!
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Now if you open your browser and go to http://localhost/index.php/hello you should see something like:
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## That was good, but we can do better
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What we did in the previous section was a good example of how easy it to create an *extremely* basic Kohana app. (In fact it's so basic, that you should never make it again!)
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If you've ever heard anything about MVC you'll probably have realised that echoing content out in a controller is strictly against the principles of MVC.
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The proper way to code with an MVC framework is to use _views_ to handle the presentation of your application, and allow the controller to do what it does best – control the flow of the request!
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Lets change our original controller slightly:
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<?php defined('SYSPATH') OR die('No Direct Script Access');
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Class Controller_Hello extends Controller_Template
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{
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public $template = 'site';
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public function action_index()
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{
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$this->template->message = 'hello, world!';
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}
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}
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`extends Controller_Template`
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: We're now extending the template controller, it makes it more convenient to use views within our controller.
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`public $template = 'site';`
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: The template controller needs to know what template you want to use. It'll automatically load the view defined in this variable and assign the view object to it.
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`$this->template->message = 'hello, world!';`
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: `$this->template` is a reference to the view object for our site template. What we're doing here is assigning a variable called "message", with a value of "hello, world!" to the view.
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Now lets try running our code...
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For some reason Kohana's thrown a wobbly and isn't showing our amazing message.
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If we look at the error message we can see that the View library wasn't able to find our site template, probably because we haven't made it yet – *doh*!
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Let's go and make the view file `application/views/site.php` for our message:
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<html>
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<head>
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<title>We've got a message for you!</title>
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<style type="text/css">
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body {font-family: Georgia;}
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h1 {font-style: italic;}
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</style>
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</head>
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<body>
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<h1><?php echo $message; ?></h1>
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<p>We just wanted to say it! :)</p>
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</body>
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</html>
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If we refresh the page then we can see the fruits of our labour:
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## Stage 3 – Profit!
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In this tutorial you've learnt how to create a controller and use a view to separate your logic from your display.
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This is obviously a very basic introduction to working with Kohana and doesn't even scrape the potential you have when developing applications with it.
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