Empty values passed to Zend framework 2 validators

Question

How can I pass an empty value through Zend framework 2 ValidatorChain to my custom validator?

It was possible on ZF1 by allowEmpty(false)

On ZF2 with empty element value :

• If allowEmpty = false, NotEmptyValidator is added to the top of ValidatorChain with breakOnFailure = true, @see Zend/InputFilter/Input#injectNotEmptyValidator.

• If allowEmpty = true, Element is considered as Valid, @see Zend/InputFilter/BaseInputFilter#isValid

  if ($input->allowEmpty()) {
      $this->validInputs[$name] = $input;
      continue;
  }
  

Answer 1

Following works for ZF2 version 2.1.1:

The problem (if I got it correctly) is that in following example, for empty values of 'fieldName', no validation is triggered. This can be quite annoying, though in

$input = new \Zend\InputFilter\Input('fieldName');

$input
    ->setAllowEmpty(true)
    ->setRequired(false)
    ->getValidatorChain()
    ->attach(new \Zend\Validator\Callback(function ($value) {
        echo 'called validator!';

        return true; // valid
    }));

$inputFilter = new \Zend\InputFilter\InputFilter();
$inputFilter->add($input);

$inputFilter->setData(array('fieldName' => 'value'));
var_dump($inputFilter->isValid()); // true, echoes 'called validator!'

$inputFilter->setData(array('fieldName' => ''));
var_dump($inputFilter->isValid()); // true, no output

$inputFilter->setData(array());
var_dump($inputFilter->isValid()); // true, no output

This is quite annoying when you have particular cases, like checking an URL assigned to a page in your CMS and avoiding collisions (empty URL is still an URL!).

There's a way of handling this for empty strings, which is to basically attach the NotEmpty validator on your own, and avoiding calls to setRequired and setAllowEmpty. This will basically tell Zend\InputFilter\Input#injectNotEmptyValidator not to utomatically attach a NotEmpty validator on its own:

$input = new \Zend\InputFilter\Input('fieldName');

$input
    ->getValidatorChain()
    ->attach(new \Zend\Validator\NotEmpty(\Zend\Validator\NotEmpty::NULL))
    ->attach(new \Zend\Validator\Callback(function ($value) {
        echo 'called validator!';

        return true; // valid
    }));

$inputFilter = new \Zend\InputFilter\InputFilter();
$inputFilter->add($input);

$inputFilter->setData(array('fieldName' => 'value'));
var_dump($inputFilter->isValid()); // true, echoes 'called validator!'

$inputFilter->setData(array('fieldName' => ''));
var_dump($inputFilter->isValid()); // true, echoes 'called validator!'

$inputFilter->setData(array());
var_dump($inputFilter->isValid()); // false (null was passed to the validator)

If you also want to check against null, you will need to extend Zend\InputFilter\Input as following:

class MyInput extends \Zend\InputFilter\Input
{
    // disabling auto-injection of the `NotEmpty` validator
    protected function injectNotEmptyValidator() {}
}

Answer 2

I see often the people making the mistake using allowEmpty in the inputFilter config arrays. The string should be written with underscore separation not with camel case. So allow_empty will work:

'fieldName' => array(
    'name'        => 'fieldName',
    'required'    => true,
    'allow_empty' => true,
    'filters' => array(
        //... your filters ...
    )
    'validators' => array(
        //... your validators ...
    ),
);

meaning a field with key 'fieldName' must be present in the data, but its value is allowed to be empty.

Answer 3

If you like to use a separate form validate class or a array notation for validate, you can do as follows:

$factory     = new Zend\InputFilter\Factory();
$inputFilter = new Zend\InputFilter\InputFilter();

$inputFilter->add($factory->createInput(array(
    'name' => 'name',
    'required' => false,
    'allowEmpty' => true,
    'filters' => array(
        array('name' => 'StripTags'),
        array('name' => 'StringTrim'),
    ),
    'validators' => array(
        array(
            'name' => 'StringLength',
            'options' => array(
                'encoding' => 'UTF-8',
                'min' => '8',
                'max' => '100',
            ),
        ),
    ),
)));

You can pass an array with required => false and allowEmpty => true to input filter factory (as I remember you can pass it directly to input filter too - not so sure).

Answer 4

This triggered validation of my Callback validator when the value was an empty string:

'required'          => false,
'allow_empty'       => false,
'continue_if_empty' => true,
'validators'        => array(
    array(
        'name'    => 'Callback',
        'options' => array(
            'callback' => function ($value, $context = []) use ($self) {
                // ...
            }
        )
    )
)

The allow_empty initially invalidates the empty string and the continue_if_empty allows it to then be evaluated by the validators that follow.

Answer 5

continue_if_empty solved my problem. Thanks to @dson-horácio-junior. This is what I used:

$this->add(array(
    'name' => 'field',
    'continue_if_empty' => true,
    'filters' => array(
        array('name' => 'StripTags'),
        array('name' => 'StringTrim')
    ),
    'validators' => array(
        array(
            'name' => 'Application\Form\Validator\Sample'
        )
    )
));

public function isValid($value, $context = null)
{
    if ($value == '' && $context['otherfield'] == '') {
        $this->error(self::INVALID_FIELD);

        return false;
    }

    // ...
}