Data Validation

For value validation, you can use the Entity::getPreparedData method

$fields = array(
    'id_user'      => array(
        Entity::OPTION_KEY_TYPE     => Entity::FIELD_TYPE_INT,
        Entity::OPTION_KEY_REQUIRED => true,
    ),
);

$data = $this->getPreparedData($_POST, $fields);
if (!$data['id_user']) {
    throw new SystemException(__('User ID is required'));
}

If you need to get the error text:

$fields = array(
    'id_student'      => array(
        Entity::OPTION_KEY_TYPE     => Entity::FIELD_TYPE_INT,
        Entity::OPTION_KEY_REQUIRED => false,
    ),
    'id_study_period' => array(
        Entity::OPTION_KEY_TYPE     => Entity::FIELD_TYPE_INT,
        Entity::OPTION_KEY_REQUIRED => true,
    ),
);

$errors = array();
$data = $this->getPreparedData($_POST, $fields, $errors);
if (!empty($errors)) {
    throw new SystemException(array_shift($errors));
}

protected function getFields(): array
    {
        return array(
            'page' => array(
                Entity::OPTION_KEY_TYPE    => Entity::FIELD_TYPE_INT,
                Entity::OPTION_KEY_DEFAULT => 1,
            ),
            'order_by' => array(
                Entity::OPTION_KEY_TYPE    => Entity::FIELD_TYPE_STRING,
                Entity::OPTION_KEY_DEFAULT => 'DESC'
            ),
        );
    } 

Available Options

• OPTION_KEY_DEFAULT - sets the default value if the field is not present
• OPTION_KEY_ERROR - sets the error text if the field is not present
• OPTION_KEY_FILTER - sets the filter type for applying filter_var
• OPTION_KEY_OBJECT_TYPE - specifies the class/interface to which the object contained in the value should belong
• OPTION_KEY_REGEXP - sets a regular expression for validation
• OPTION_KEY_REQUIRED - indicates whether the field is mandatory
• OPTION_KEY_TYPE - indicates what type the value should be converted to (Available value types)
• OPTION_KEY_RULE - specifies a function for custom validation rules

Available Value Types

• FIELD_TYPE_ARRAY
• FIELD_TYPE_BOOL
• FIELD_TYPE_FILE
• FIELD_TYPE_FLOAT
• FIELD_TYPE_INT
• FIELD_TYPE_JSON
• FIELD_TYPE_METHOD
• FIELD_TYPE_OBJECT
• FIELD_TYPE_SECURITY_STRING
• FIELD_TYPE_STRING
• FIELD_TYPE_STRING_NULL

Example of OPTION_KEY_RULE

    public function testGetPreparedDataCustomRulePositive(): void
    {
        $fields = array(
            'id' => array(
                Entity::OPTION_KEY_TYPE => Entity::FIELD_TYPE_INT,
                Entity::OPTION_KEY_RULE => static function ($value, ?string &$error) {
                    if ($value < 1) {
                        $error = 'Must be greater than 0!';
                        return false;
                    }

                    return $value;
                },
            ),
        );

        $errors = array();
        $data = $this->entity->getPreparedData($_REQUEST, $fields, $errors);
    }