Validation
----------
Phalcon\Validation is an independent validation component to validate an arbitrary set of data.
This component can be used to implement validation rules that does not belong to a model or collection.

The following example shows its basic usage:

.. code-block:: php

	use Phalcon\Validation\Validator\PresenceOf,
		Phalcon\Validation\Validator\Email;

	$validation = new Phalcon\Validation();

	$validation->add('name', new PresenceOf(
		'message' => 'The name is required'
	));

	$validation->add('email', new PresenceOf(
		'message' => 'The e-mail is required'
	));

	$validation->add('email', new Email(
		'message' => 'The e-mail is not valid'
	));

	$messages = $validation->validate($_POST);
	if (count($messages)) {
		foreach ($messages as $message) {
			echo $message, '<br>;
		}
	}

Validators
----------
Phalcon exposes a set of built-in validators for this component:

+--------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------+
| Name         | Explanation                                                                                                                                                      | Example                                                           |
+==============+==================================================================================================================================================================+===================================================================+
| PresenceOf   | Validates that a field's value isn't null or empty string.                                                                                                       | :doc:`Example <../api/Phalcon_Validation_Validator_PresenceOf>`   |
+--------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------+
| Email        | Validates that field contains a valid email format                                                                                                               | :doc:`Example <../api/Phalcon_Validation_Validator_Email>`        |
+--------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------+
| ExclusionIn  | Validates that a value is not within a list of possible values                                                                                                   | :doc:`Example <../api/Phalcon_Validation_Validator_Exclusionin>`  |
+--------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------+
| InclusionIn  | Validates that a value is within a list of possible values                                                                                                       | :doc:`Example <../api/Phalcon_Validation_Validator_Inclusionin>`  |
+--------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------+
| Regex        | Validates that the value of a field matches a regular expression                                                                                                 | :doc:`Example <../api/Phalcon_Validation_Validator_Regex>`        |
+--------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------+
| StringLength | Validates the length of a string                                                                                                                                 | :doc:`Example <../api/Phalcon_Validation_Validator_StringLength>` |
+--------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------+

Additional validators can be created by the developer. The following class explains how to create a validator for this component:

.. code-block:: php