Form API Validation

This module extends the form API to include convenient access to common for submission filters and validation checks. The core form API has no built in validators available to you, nor filters, and all have to be manually placed in a validation function. With this module you simply add the basic filers and/or validators you want to have in your form render area.

You can use the existent filters and rules or create your own. This module is fully extensible using hooks, allowing you to easily add your own and reuse them throughout the site. Abstraction at it's finest!

Available Validators

Rule	Usage	Description
numeric	numeric	Must contains only numbers.
alpha	alpha	Must contains only alpha characters.
length	length[<total>], length[<min>, <max>], length[<min>, *]
chars	chars[<char 1>, <char 2>, ..., <char N>]	Accept only specified characters.
email	email	Valid email
url	url, url[absolute]	Valid URL. If absolute parameter is specified, the field value must have to be a full URL.
ipv4	ipv4	Valid IPv4
alpha_numeric	alpha_numeric	Accept only Alpha Numeric characters
alpha_dash	alpha_dash	Accept only Alpha characters and Dash ( - )
digit	digit	Checks wheter a string consists of digits only (no dots or dashes).
decimal	decimal, decimal[<digits>,<decimals>]
regexp	regexp[/^regular expression$/]	PCRE Regular Expression
match_field	match_field[otherfield]	Check if the field has same value of otherfield.
range	range[<min>, <max>]	Check if the field value is in defined range.

Available Filters

Filter	Description
numeric	Remove all non numeric characters.
trim	Remove all spaces before and after value.
uppercase	Transform all characters to upper case.
lowercase	Transform all characters to lower case.
strip_tags	Strips out ALL html tags.
html_entities	Decodes all previously encoded entities, and then encodes all entities.

Usage

Example:

<?php
//...

$form['myfield'] = array(
  '#type' => 'textfield',
  '#title' => 'My Field',
  '#required' => TRUE,
  '#validators' => array(
    'email', 
    'length[10, 50]', 
    array('rule' => 'alpha_numeric', 'error' => 'Please, use only alpha numeric characters at %field.'),
    array('rule' => 'match_field[otherfield]', 'error callback' => 'mymodule_validation_error_msg'),
  ),
  '#filters' => array('trim', 'uppercase')
);

//...

function mymodule_validation_error_msg($rule, $params, $element, $form_state) {
  return t("My custom error message for %field", array("%field" => $element['#title']));
}

Custom Validator / Filter

The Validator or Filter was built using the Drupal Plugin API, so to create your own custom validator or filter you should use the FapiValidationValidator or FapiValidationFilter Annontation and it respective implementation class.

Validators

First you have to create a file at src/Plugin/FapiValidationValidator/MyCustomValidator.php path of your module with the class implementation.

<?php

namespace Drupal\my_module\Plugin\FapiValidationValidator;

use Drupal\Core\Form\FormStateInterface;
use Drupal\fapi_validation\FapiValidationValidatorsInterface;
use Drupal\fapi_validation\Validator;

/**
 * Provides a custom validation.
 *
 * Field must have JonhDoe as value.
 *
 * @FapiValidationValidator(
 *   id = "custom_validator",
 *   error_message = "Type the text 'custom value' at field %field."
 * )
 */
class MyCustomValidator implements FapiValidationValidatorsInterface {
  /**
   * {@inheritdoc}
   */
  public function validate(Validator $validator, array $element, FormStateInterface $form_state) {
    return $validator->getValue() == 'custom value';
  }
}

Now you are able to use at your form definiton.

//...

    $form['custom_field'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Custom Field'),
      '#description' => $this->t('The Value should be "custom value".'),
      '#validators' => [
        'custom_validator',
      ],
      '#required' => TRUE,
    ];

//...

Processed Error Messages

If you need create a error message programaticaly, change the error_message key at annotation to error_callback with the public static method name.

//...

/**
 * @FapiValidationValidator(
 *   id = "custom_validator",
 *   error_callback = "processError"
 * )
 */
class MyCustomValidator implements FapiValidationValidatorsInterface {
  //...
  
  /**
   * Process custom error.
   *
   * @param Drupal\fapi_validation\Validator $validator
   *   Validator.
   * @param array $element
   *   Form element.
   *
   * @return string
   *   Error message.
   */
  public static function processError(Validator $validator, array $element) {
    $params = [
      '%value' => $validator->getValue(),
      '%field' => $element['#title'],
    ];
    return \t("You must enter 'custom value' as value and not '%value' at field %field", $params);
  }
}

Filters

First you have to create a file at src/Plugin/FapiValidationFilter/MyCustomFilter.php path of your module with the class implementation.

<?php

namespace Drupal\my_module\Plugin\FapiValidationFilter;

use Drupal\fapi_validation\FapiValidationFiltersInterface;

/**
 * Fapi Validation Plugin for remove Numeric filter.
 *
 * @FapiValidationFilter(
 *   id = "custom_filter"
 * )
 */
class MyCustomFilter implements FapiValidationFiltersInterface {

  /**
   * {@inheritdoc}
   */
  public function filter($value) {
    return preg_replace('/[^0-5]+/', '', $value);
  }
}

Now you are able to use at your form definiton.

//...

    $form['custom_field'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Custom Field'),
      '#filters' => [
        'custom_filter',
      ],
      '#required' => TRUE,
    ];

//...