Custom validator not found by ValidatorPluginManager - php

Question

I'm struggling with getting my custom validator to work.
The thing is I have a custom form element that uses a custom validator.
But when field is being created the ValidatorPluginManager fails to find my custom validator.
Now I know that it's a scope issue but I can' resolve it.
Error message:
A plugin by the name "AliasExists" was not found in the plugin manager Zend\Validator\ValidatorPluginManager
Validator code:
class AliasExists
extends AbstractValidator
implements AdapterAwareInterface
{
use AdapterAwareTrait;
const NOT_UNIQUE = 'notUnique';
/**
* Validation failure message templates definition
*
* #var array
*/
protected $messageTemplates = [
self::NOT_UNIQUE => "Entry with alias %value% already exists",
];
/**
* #var string
*/
protected $table;
/**
* #var Select
*/
protected $select;
/**
* #var string
*/
protected $categoryField = 'category';
/**
* #var int
*/
protected $categoryValue;
public function __construct($options)
{
parent::__construct($options);
if ($options instanceof Traversable) {
$options = ArrayUtils::iteratorToArray($options);
} elseif ($options instanceof Adapter) {
$temp = [];
$temp['adapter'] = $options;
$options = $temp;
} else {
if (func_num_args() > 1) {
$options = func_get_args();
$firstArgument = array_shift($options);
if (is_array($firstArgument)) {
$temp = ArrayUtils::iteratorToArray($firstArgument);
} else {
$temp['table'] = $firstArgument;
}
if (!empty($options)) {
$temp['adapter'] = array_shift($options);
}
$options = $temp;
}
}
if (array_key_exists('table', $options)) {
$this->setTable($options['table']);
}
if (array_key_exists('adapter', $options)) {
$this->setAdapter($options['adapter']);
}
}
public function isValid($value, $context = null)
{
if (null === $this->adapter) {
throw new \RuntimeException('No database adapter set.');
}
if (empty($this->table)) {
throw new \RuntimeException('Table has not been set.');
}
$valid = true;
$this->setValue($value);
if ($context) {
// TODO
}
$result = $this->query($value);
if (!$result) {
$valid = false;
$this->error(self::NOT_UNIQUE);
}
return $valid;
}
public function getSelect()
{
if ($this->select instanceof Select) {
return $this->select;
}
$select = new Select();
$table = new TableIdentifier($this->table);
$select->from($table);
$select->where->equalTo(
'alias',
null
);
if (!empty($this->categoryField) && !empty($this->categoryValue)) {
$select->where->equalTo(
$this->categoryField,
$this->categoryValue
);
}
$select->columns(['id']);
$this->select = $select;
return $this->select;
}
/**
* Returns the set adapter
*
* #return Adapter
*/
public function getAdapter(): Adapter
{
return $this->adapter;
}
/**
* Sets a (new) DB adapter
*
* #param Adapter $adapter
* #return self Provides a fluent interface
*/
public function setAdapter(Adapter $adapter)
{
return $this->setDbAdapter($adapter);
}
/**
* Returns the set table
*
* #return string
*/
public function getTable(): string
{
return $this->table;
}
/**
* Sets a (new) table
*
* #param string $table
* #return self Provides a fluent interface
*/
public function setTable(string $table)
{
$this->table = $table;
$this->select = null;
return $this;
}
/**
* #return string
*/
public function getCategoryField(): string
{
return $this->categoryField;
}
/**
* #param string $categoryField
*/
public function setCategoryField(string $categoryField)
{
$this->categoryField = $categoryField;
}
/**
* #return int
*/
public function getCategoryValue(): int
{
return $this->categoryValue;
}
/**
* #param int $categoryValue
*/
public function setCategoryValue(int $categoryValue)
{
$this->categoryValue = $categoryValue;
}
protected function query($value)
{
$sql = new Sql($this->getAdapter());
$select = $this->getSelect();
$statement = $sql->prepareStatementForSqlObject($select);
$parameters = $statement->getParameterContainer();
$parameters['where1'] = (string)$value;
$result = $statement->execute();
return $result->current();
}
}
Validator factory:
class AliasExistsFactory implements FactoryInterface
{
public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
{
$db = $container->get(AdapterInterface::class);
return new AliasExists($db);
}
}
Custom form element code:
class Alias
extends Text
implements InputProviderInterface
{
protected $attributes = [
'name' => 'alias',
'required' => 'required',
'class' => 'form-control',
];
protected $label = 'Alias';
public function __construct($name = null, array $options = [])
{
parent::__construct($name, $options);
$this->setAttribute('id', $this->getName());
}
public function getInputSpecification()
{
return [
'name' => $this->getName(),
'required' => true,
'filters' => [
['name' => 'StringTrim'],
['name' => 'StringToLower'],
],
'validators' => [
[
'name' => 'NotEmpty',
'options' => [
'type' => 'string'
],
],
[
'name' => 'Regex',
'options' => [
'pattern' => '/^[0-9a-zA-Z-_]+$/',
'messages' => [
Regex::NOT_MATCH => 'Only numbers, underscore, dash and characters from A to Z are allowed'
],
],
],
[
'name' => 'StringLength',
'options' => [
'min' => 1,
'max' => 255
],
],
[
'name' => 'AliasExists', <--- Custom validator
]
],
];
}
}
module.config.php
'form_elements' => [
'factories' => [
Form\Element\Alias::class => InvokableFactory::class,
],
],
'validators' => [
'factories' => [
Validator\AliasExists::class => Factory\AliasExistsFactory::class,
],
'aliases' => [
'AliasExists' => Validator\AliasExists::class,
]
]
Controller factory that instantiates form that has this custom field:
class EditControllerFactory implements FactoryInterface
{
public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
{
$formManager = $container->get('FormElementManager');
$form = $formManager->get(ArticleForm::class);
return new EditController($form);
}
}
The only way I can get my custom validator to work is (as found in this answer Possible to create a factory to instantiate custom Form validators?) is to set validator chain in controller factory that instantiates form but its an overkill to have to do this in every controller factory that could possibly have a form that uses this field that has custom validator in it.