Zend Form 2 multiselect field is empty after validation - php

Question

I'm not sure what's going on. I'm using Zend Form 2 with a multiselect field. When I submit the code, the values exist in post. When I run the values through zend form 2, I get no validation errors but the multiselect field is suddenly empty.
class Form extends \Zend\Form\Form
{
// input filter to set up filters and validators
protected $myInputFilter;
public function __construct()
{
// create the zend form
parent::__construct();
// make it a bootstrap form
$this->setAttribute('class', 'form-horizontal');
$this->setAttribute('role', 'form');
// set the default objects we'll use to build the form validator
$this->myInputFilter = new \Zend\InputFilter\InputFilter();
}
}
class AddPublicationForm extends Form
{
public function __construct()
{
// create the zend form
parent::__construct();
$this->setAttribute('class', 'form-horizontal');
$this->setAttribute('id', 'add-publication-form');
$this->add([
'name' => 'author[]',
'attributes' => [
'class' => 'form-control',
'data-placeholder' => 'Author',
'multiple' => 'multiple',
'placeholder' => 'Author',
],
'required' => false,
'type' => \Zend\Form\Element\Select::class,
'options' => [
'value_options' => [
'check1' => 'check1',
'check2' => 'check2',
],
],
]);
$this->myInputFilter->add([
'filters' => [],
'name' => 'author[]',
'required' => false,
'validators' => [],
]);
// attach validators and filters
$this->setInputFilter($this->myInputFilter);
// prepare the form
$this->prepare();
}
}
These are the zend form objects that I am using. I am using Slim Framework 2 as my backend. Here is the controller object:
public function addAction()
{
$request = $this->app->request;
$form = new Form\AddPublicationForm();
if ($request->isPost()) {
$params = $request->params();
// DUMP 1: exit('<pre>'.print_r($params, true).'</pre>');
$form->setData($params);
if ($form->isValid()) {
$data = $form->getData();
// DUMP 2: exit('<pre>'.print_r($data, true).'</pre>');
}
}
}
DUMP 1:
Array
(
[author] => Array
(
[0] => check1
[1] => check2
)
}
DUMP 2:
Array
(
[author[]] =>
)
I realize that I could very easily just bypass the validation here because I'm not using any validators on that field. I'm more concerned with the underlying cause though.
Why is the validated author data empty?

Answer 1

When you specify multiple in attributes, Zend\Form and Zend\InputFilter add []after the name. You should not do it yourself otherwise, in the html code, the element appears under the name author[][] and the setData method don't match.
To see it, replace required by true and look at the html code of the form.
$this->add([
'name' => 'author',
'attributes' => [
'class' => 'form-control',
'data-placeholder' => 'Author',
'multiple' => 'multiple',
'placeholder' => 'Author',
],
'required' => false,
'type' => \Zend\Form\Element\Select::class,
'options' => [
'value_options' => [
'check1' => 'check1',
'check2' => 'check2',
],
],
]);
$this->myInputFilter->add([
'filters' => [],
'name' => 'author',
'required' => false,
'validators' => [],
]);