CakePHP: Hello World!

CakePHP is an MVC framework. Model, view, controller are the main components. Generally speaking, the model is an object and is used to operate database. You should employ it to communicate with database, like inserting, deleting, querying. The view is as its name. It is used to display the result. Usually it contains lots of HTML but few PHP code. The controller is employed to handle HTTP requests and do some logic. The controller is central in an MVC pattern. It calls the model to get data from database, then do some work, and sends the result to a view to display.

Let's have a look at CakePHP. I will use CakePHP to write a "hello world" program. My CakePHP is located in D:\xampplite\htdocs\cake. In it there are four directories: app, cake, docs, vendors. "app" is the working directory where we should save our code. Now let's write some codes.

<?php
class TestersController extends Controller{
  var $uses=null;
  var $autoRender=false;
  function sayHello(){
    echo 'Hello, CakePHP!';
  }
}
?>

As you see, the name of the controller class is TestersController. i.e. The controller's name is Testers. According to the CakePHP convention, the controller's name should be plural form. You must save it as "testers_controller" in app\controllers so that CakePHP can find the controller class.

Before you run it, please make sure that mod_rewrite is on. Check your Apache http.conf, find the line like "LoadModule rewrite_module modules/mod_rewrite.so". If it is commented, just uncomment it (remove "#"). Now start or restart (if you modified http.conf) Apache server. Enter http://localhost/cake/testers/sayHello in your browser's address bar. You can see the result if no problem happens:

Now let me explain the program in detail. In the TestersController class I define two variables: $uses and $autoRender. $uses specifies which models the controller can use. I set it "null" so that it don't use any model. If I omit it, CakePHP will look for the model "Tester" automatically. That will produce an error because I haven't created the model class. See below:

$autoRender=false makes CakePHP not search for the view for TestersController::sayHello() because I haven't create the view. If it is omitted, a missing view error will occurred.

The function sayHello() is called "action" in the controller class. That's to say, A controller may have several actions to handle different tasks, and each action is just a function in the controller class. Controllers and actions are mapped into URL. For example, when we open http://localhost/cake/testers/sayHello, CakePHP will find TestersController class and execute sayHello() function automatically. We can call any action by typing different URLs.

That's all. In this example I just used controller to write a "hello world" program. It is just beginning. There are many features in CakePHP. I hope my articles will be helpful for you.

Update: To simplify the example, I use "echo" statement in the controller. That's a bad style. In fact, we should use "view" to show data or result. If you are interested, see Working with View.