Category Archives: Kohana

kohana-view

Using Views in Kohana 3

What is a View?

If you’ve never worked with Kohana Views in the past, they’re not hard to understand. Controllers handle most of your logic, Models handle the database communication, and Views handle the presentation of the data (generally-speaking). In Kohana, views are very easy to work with. Unfortunately, a fresh install of Kohana won’t contain a default view for you so we’ll have to make one ourselves. I trust you’ve installed and configured Kohana 3 on your server and are ready for what follows.

Adding our first View

Stepping back a moment, by default Kohana’s example controller sends text directly to the output without loading a view – perhaps you’ll find cases where this is desirable (especially when debugging), but for the most part it’s not what you’ll want to be doing. When developing your next project, you’ll want to build views that represent templates, modules, and many other aspects of your design.

Suppose we have the following saved to application/views/myview.php

<p>If you see me, the view loaded.</p>

This is nothing more than a paragraph element and some static text, but let’s load it from within a controller. I should mention that there are a couple different ways you can load a view, but they’re all pretty straight forward and intuitive.

Loading our View

class Controller_Demo extends Controller {
  public function action_index()
  {
    $this->request->response = View::factory( 'myview' );
  }
}

In this case we’re using the static factory method of the View class to load the view file we previously created. Note also that I’m not providing the .php extension – Kohana figures that out for itself. If myview.php was in a subfolder, we would reflect that in the path passed to the factory method.

Kohana 3 is loaded onto my localhost, so visiting http://localhost/kohana/demo/index results in showing me the contents of my view, meaning the view was loaded properly. If your view isn’t loading properly, make sure you placed it within application/views, and that your controller code contains no mistakes.

Handling a View from a variable

Another way to load a view is to place it within a variable reference, and then pass that into the response.

class Controller_Demo extends Controller {
  public function action_index()
  {
    $view = View::factory( 'myview' );
    $this->request->response = $view->render();
  }
}

With time you’ll settle on the method you prefer most. In fact, what we’re about to cover might help determine which method you prefer most.

Passing Data to your View

Views are not necessarily restricted to being static files – they wouldn’t be all that useful if they were. Controllers can pass variables into views to be displayed upon pages. Let’s go back to our view from above and change our static text to something a bit more dynamic and open to more possibilities:

<p><?php echo $message; ?></p>

Here our view is expecting to display the $message variable, so we have to be sure to provide this value within our controller. Passing variables and values into views is also a task that can be done a couple different ways. One very common method is to create an associative array, and pass that into the static factory method:

class Controller_Demo extends Controller {
  public function action_index()
  {
    $data['message'] = "Hello, World";
    $this->request->response = View::factory( 'myview', $data );
  }
}

What this does is makes all $data array keys available within the view as variables themselves, so $data[‘message’] within the view is $message. Refreshing your page should result in a new message, “Hello, World”.

Adding Data via the Set Method

The view class also contains many method to allow the adding data on a variable-by-variable basis. We can use the set method to add a variable to a view as well.

class Controller_Demo extends Controller {
  public function action_index()
  {
    $this->request->response = View::factory( 'myview' )
      ->set( 'message', 'Hello, World' );
  }
}

The set method of the view class accepts two parameters: 1) The key, and 2) the value. Like the previous method, this also creates a variable called $message within the view with whatever value you provide. The set method also allows you to add an array of values:

class Controller_Demo extends Controller {
  public function action_index()
  {
    $this->request->response = View::factory( 'myview' )
      ->set( array( 'Name' => 'Jonathan', 'Year' => 2011 ) );
  }
}

When you provide an array, the set method will cycle through your array and add all of your values as if you had done each one of them individually with the previous style of using the set method.

Chaining the Set Method

Another thing to note about the set method is that it’s chainable, meaning you can run it over and over and over again.

class Controller_Demo extends Controller {
  public function action_index()
  {
    $this->request->response = View::factory( 'myview' )
      ->set( 'name', 'Jonathan' )
      ->set( 'year', '2011' )
      ->set( 'website', 'http://sampsonresume.com' );
  }
}

Working directly with the View

So far we’ve been using the set method in conjunction with the static factory method, but you can do the same thing even if you apply the view to a variable earlier in the control:

class Controller_Demo extends Controller {
  public function action_index()
  {
    $view = View::factory('myview');
    $view->set( 'name', 'Jonathan' );
    $this->request->response = $view->render();
  }
}

Another method of adding data is to just add it directly to the view object itself:

class Controller_Demo extends Controller {
  public function action_index()
  {
    $view = View::factory('myview');
    $view->message = "Hello, World";
    $this->request->response = $view->render();
  }
}

Setting Global Variables

At times you may want to make a variable available to all views that are loaded. The view class makes this easy as well via its global data array.

class Controller_Demo extends Controller {
  public function action_index()
  {
    View::set_global('message', 'Hello World');
    $this->request->response = View::factory('myview')
      ->set( 'myWidget', View::factory('anotherview') );
  }
}

In this example you can see that we call the set_global method early in the controller logic. The variable $message will now be available in all views loaded. You can also see that I’ve loaded a second view into the first, and represented it with the variable $myWidget. Both views can reliably access the global $message variable now.

There’s still a lot more you can do with views, like passing variables by reference via the bind method. The bind method is just like the set method, with the one caveat that the variable is being passed by reference and isn’t being copied:

class Controller_Demo extends Controller {
  public function action_index()
  {
    $view = View::factory( 'myview' );
    $myVal = "Hello, World";
    $view->bind( 'message', $myVal );
    $this->request->response = $view;
  }
}

In this example $myVal is being assigned by reference to $view->message. If the value of $myVal changes, this change will reflect automatically within $view->message since the value is assigned by reference via the bind method. You can also use the bind_global method if you need set_global functionality while maintaining references.

Kohana checks environment to ensure it can run properly with present configuration.

Install and Setup of Kohana 3, The

Kohana is the wildly popular PHP Framework used by many developers all over. I’ve used it numerous times in the past on some rather different projects and found it to be pretty versatile and reliable over-all. One of my largest projects received well over 100,000 unique visitors a day, and still managed to hold up exceptionally well under the stress.

This post will serve as nothing more than a guide to installing Kohana version 3.

Environment

In order to run Kohana you will need a server, but don’t worry too much as your average computer will do. I develop on windows (for now) so I typically install WAMPServer, which places Apache, MySQL, and PHP all on my box inside a live server environment so that I can develop on the domain http://localhost/ – awfully handy.

Depending on what operating system you’re using, you may not find WAMPServer to be all that helpful. There are always alternatives: MAMP and XAMPP are two popular ones.

The Classic Download, Copy and Paste Procedure

Like so many other frameworks, we’ll begin with downloading Kohana and extracting the files into our project directory. You can download Kohana 3 from the Kohana download page. At the time of this writing, the latest (stable) version is 3.0.9, which also happens to be the version I’ll use in the following examples.

Extract the contents of your download to your project directory. You may keep the standard /kohana folder that comes in the archive, or you can just pull the files themselves our and into your directory. Once you have this done though, load up your favorite browser and navigate to your project directory to begin the requirements testing.

Kohana checks environment to ensure it can run properly with present configuration.

This stage will test your environment for Kohana┬ácompatibility. Kohana will need to ensure that your server configuration allows for writable log directories, appropriate versions of PHP and so much more. This screen will give you a nice rundown of how you stack up. All green is all good, but if Kohana finds something it doesn’t like (like unwritable directories) be sure to handle it here and refresh to re-check your system.

If you require assistance setting up your server environment to allow for writable directories, or enabling extensions in the PHP library, please consider visiting serverfault, and online peer-reviewed question and answer website for server maintenance.

As indicated in the automated test, once your system is clear you may delete (or rename) the install.php file to continue the process of setting up Kohana 3.

Setting the Base URL

Some of you may have refreshed your browser only to find a aesthetically pleasing (yet heartbreaking) error on your screen. You got antsy, slow down and keep reading (we’re almost done, I promise). The next thing we need to do is update our base bath to the project on our server.

Kohana uses Apache’s mod_rewrite to beautify your url structure. Much of this logic exists within the example.htaccess file found immediately within your Kohana directory. Open this up to make our next edit.

If necessary, let’s update the following line:

# Installation directory
RewriteBase /

If your project is immediately inside your /www or /htdocs folder (your web-server directory) then you can leave this as /, however if you’ve created a project folder to house your Kohana application you need to point this to where that project is. Hint: it’s the same path that we accessed to get to the previous phase, the system check.

My project happens to be in a custom path, so I’ll update my example.htaccess file.

# Installation directory
RewriteBase /projects/demoKohana/website

When you are ready to save this file, save it as .htaccess in the same directory. It’s an odd filename, but trust me on this. This file is handled by Apache and often times contains very important rules for how requests ought to be handled. You can read more about .htaccess on the Apache website.

Now that we’ve modified the .htaccess file, our directory ought to look like this:

Basic Kohana 3 root directory appearance.

  • application (folder)
  • modules (folder)
  • system (folder)
  • .htaccess
  • build.xml
  • DEVELOPERS.md
  • example.htaccess
  • index.php
  • LICENSE.md
  • install.php (deleted or renamed)
  • README.md

If this looks like your directory, you’re well on your way to finishing the setup process.

Once you’ve confirmed your directory structure is correct, we can move on to the the final touches before starting development with the Kohana 3 framework.

Updating the Bootstrap

Our next, and final, step is to update an array found within application/bootstrap.php. Within bootstrap.php, locate the following lines:

Kohana::init(array(
	'base_url' => '/',
));

Here, again, we’ll want to change the base_url value. Within a comment the Kohana developers tell us that this value represents the “path, and optionally domain, of your application.” As such, if you want to provide the domain you are more than welcome to. I will be using a path instead:

Kohana::init(array(
	'base_url' => '/projects/demoKohana/website',
));

Save, and exit.

At this point, if all went as it should, you should be able to refresh your project directory and find one of the most glorious messages developers have enjoyed since 1974.

To the Controller!

By default, Kohana will run the index action of the default Welcome controller. The default controller and action are set within the bootstrap.php file, located just inside the applications folder. Locate the following lines:

Route::set('default', '(<controller>(/<action>(/<id>)))')
	->defaults(array(
		'controller' => 'welcome',
		'action'     => 'index',
	));

If you would like to change the controller and/or action, you may do so here. Instead of changing the present values, I’m going to leave them as they are and simply take a look at the welcome controller. You can find the welcome controller source located inside application/classes/controllers under the filename welcome.php:

<?php defined('SYSPATH') or die('No direct script access.');

class Controller_Welcome extends Controller {

	public function action_index()
	{
		$this->request->response = 'hello, world!';
	}

} // End Welcome

You can see from this code that all the action_index() method does is send the ‘hello, world!’ message directly to the response. No views are being loaded, so we’ll go ahead and load a view now. We’ll start by creating a new file at application/views/welcome.php and placing within it the text “This is my view.” Next, back in our controller we will make the following change to the action_index method body:

//$this->request->response = 'hello, world!';
$this->request->response = View::factory( 'welcome' );

Here we are loading the welcome view into the response. This now allows us to make changes to our applications/views/welcome.php file rather than modifying the output within the controller itself.

Next up, Using Views in Kohana 3.