How to create custom filter in CakePHP?

CakePHP is a popular PHP development framework that provides many powerful features that enable developers to quickly build reliable web applications. One of these features is filters.

A filter is a technology used to inspect, transform, or filter incoming request data. In CakePHP, filters can be applied to controller methods or model operations, thus ensuring the safety and correctness of the application. In this article, we will cover how to create custom filters in CakePHP.

Step One: Create a Custom Filter

To create a custom filter, we need to create a file called CustomFilter.php and place it under the lib folder . Then, add the following code:

App::uses('Sanitize', 'Utility');
class CustomFilter
{
    public function url($string)
    {
        return Sanitize::clean($string, array('encode' => false, 'remove_html' => true));
    }

    public function email($string)
    {
        return Sanitize::clean($string, array('encode' => false, 'remove_html' => true));
    }
}

The above code creates a class named CustomFilter, which contains two functions url() and email(), which are used to filter URL and Email request data. The Sanitize class that comes with CakePHP is used here, which provides a series of functions that can be used for data filtering.

In this code, we use the Sanitize::clean() method, which accepts two parameters: a string that needs to be filtered and filter options. Use the "encode" option to encode the data into HTML entities, while using the "remove_html" option will remove HTML tags from the string.

Step 2: Add the custom filter to CakePHP

In order to let CakePHP know that we have created a custom filter, we need to add the following code to app/Config/bootstrap.php In the file:

App::uses('CustomFilter', 'Lib');
CakeEventManager::instance()->attach(new CustomFilter());

The first line of code introduces the CustomFilter class we just created, while the second line adds the CustomFilter instance to the CakePHP event manager.

Step 3: Use custom filters in Controller

Now, we can use the filter we just created in Controller. Suppose we have a UserController class and there is a method called register() in the class as shown below:

class UserController extends AppController
{
    public function register()
    {
        $email = $this->request->data['User']['email'];

        // 对email进行过滤
        $email = $this->CustomFilter->email($email);

        // 保存用户
        $this->User->save($this->request->data);
    }
}

In this example, we first get the email value from the request data and add it Passed to the email() method of the CustomFilter class for filtering. We then use the User model to save the request data to the database.

Step 4: Use custom filters in Model

We can also use custom filters in Model. Suppose we have a User model with a method called register() as shown below:

class User extends AppModel
{
    public $validate = array(
        'email' => array(
            'rule' => 'email',
            'message' => 'Invalid email address'
        )
    );

    public function beforeSave($options = array())
    {
        $this->data['User']['email'] = $this->CustomFilter->email($this->data['User']['email']);
        return true;
    }
}

In this example, we first check if the incoming email address is valid using the $email validation rule. Then, in the beforeSave() method, we use the email() method of the CustomFilter class to filter the email address.

Summary

Creating custom filters in CakePHP is very simple. By creating a CustomFilter class and adding it to the event manager, we can filter the request data passed in controller methods and model operations. This improves application security and reliability and makes web development easier.

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