How to use form validation in CakePHP framework?

CakePHP framework is a popular PHP framework that provides a form validation mechanism with rich functions that can help developers process form data more easily, efficiently and reliably. In this article, we will introduce how to use form validation in CakePHP framework.

1. Create form

First, we need to create a form, which will be used to submit data to the server for processing. In the CakePHP framework, we can use the form helper class, which provides methods to create forms and can automatically add form validation rules. The following is a simple form example:

<?= $this->Form->create($user) ?>
    <?= $this->Form->input('username') ?>
    <?= $this->Form->input('password') ?>
    <?= $this->Form->button(__('Submit')) ?>
<?= $this->Form->end() ?>

In the above code, we used the $this->Form->create() method to create the form and passed A variable named $user serves as the form data source. Then, we used the $this->Form->input() method to create two form input boxes for entering usernames and passwords. Finally, we create a submit button using the $this->Form->button() method. When the user clicks the button, the form data will be submitted to the server.

2. Create validation rules

Next, we need to create some validation rules to ensure that the submitted form data meets our requirements. In the CakePHP framework, we can use the validation component, which provides some built-in validation rules, such as required, minimum length, maximum value, etc.

The following is a simple validation rule example:

<?php
namespace AppModelEntity;

use CakeORMEntity;
use CakeAuthDefaultPasswordHasher;

class User extends Entity
{
    protected $_accessible = [
        '*' => true,
        'id' => false
    ];

    protected function _setPassword($password)
    {
        return (new DefaultPasswordHasher)->hash($password);
    }

    public function validationDefault(Validator $validator)
    {
        $validator
            ->notEmptyString('username', __('Username cannot be empty'))
            ->maxLength('username', 50, __('Username cannot be longer than 50 characters'))
            ->notEmptyString('password', __('Password cannot be empty'))
            ->maxLength('password', 255, __('Password cannot be longer than 255 characters'));

        return $validator;
    }
}

In the above code, we created an entity class named User and defined a name It is the method of validationDefault(). In this method, we use the validator object to define several verification rules, such as the user name is required, the user name cannot exceed 50 characters, the password is required, and the password cannot exceed 255 characters, etc.

3. Apply Validation Rules

Finally, we need to apply validation rules to our form, this will ensure that the submitted form data meets our requirements. In the CakePHP framework, we can use the following steps to apply validation rules:

public function add()
{
    $user = $this->Users->newEntity();
    if ($this->request->is('post')) {
        $user = $this->Users->patchEntity($user, $this->request->getData());
        if ($this->Users->save($user)) {
            $this->Flash->success(__('The user has been saved.'));

            return $this->redirect(['action' => 'index']);
        }
        $this->Flash->error(__('The user could not be saved. Please, try again.'));
    }
    $this->set(compact('user'));
    $this->viewBuilder()->setLayout('login');
}

In the above code, we have created a method called add() for processing the form submit. In this method, we first create an entity object named $user to store form data. We then populate the submitted form data into the entity object using the $this->Users->patchEntity() method, and $this->Users->save( )Method to save entity objects.

If the save is successful, we use the $this->Flash->success() method to display a success message and redirect to the user list page. If the save fails, we use the $this->Flash->error() method to display the error message and re-render the form page.

Finally, we pass the entity object to the view and set the view layout to login.

Summary

In this article, we introduced how to use form validation in the CakePHP framework. You can use the form helper class to create the form, use the validation component to create validation rules, and use the patchEntity() method to populate the form data into the entity object. When trying to save an entity object, the CakePHP framework will automatically apply validation rules and return a validation error message. These features make the CakePHP framework a powerful tool that helps you work with form data more easily.

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