Unable to retrieve slected values in Multiselect form element

[shifra123]

Preconditions

1. Magento ver. 2.1.5
2. PHP 7.0.16-3+deb.sury.org-trusty+1 (cli) (built: Feb 22 2017 10:27:05) ( NTS ) Copyright (c) 1997-2017 The PHP Group Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies with Zend OPcache v7.0.16-3+deb.sury.org-trusty+1, Copyright (c) 1999-2017, by Zend Technologies with Xdebug v2.5.0, Copyright (c) 2002-2016, by Derick Rethans

Issue happens when adding a custom tab to customer_form.xml via block file

Steps to reproduce

1. Add block to customer_index_edit.xml layout

2. Block file extends \Magento\Backend\Block\Widget\Form\Generic implements TabInterface

3. In function _prepareForm() adding a new filedset that will add a new form element

   
   $fieldset = $form->addFieldset('base_fieldset', ['legend' => __('Destinations')]);
   $fieldset->addField(
           'destination',
           'multiselect',
           [
               'name' => 'destination[]',
               'data-form-part' => $this->getData('target_form'),
               'label' => __('Destination'),
               'title' => __('Destination'),
               'values' => array( '1'=> array( 'label' => 'Customer', 'value' => 'customer'),
                   '2'=> array( 'label' => 'Shipping Agent', 'value' => 'shipping_agent'),
                   '3'=> array( 'label' => 'Customer Representative', 'value' => 'customer_representative'),
               ),
               'disabled' => false,
           ]
       );

4. Run code

5. Select more then one option in multiselect above

6. Save form

7. In save controller check the value of this $this->getRequest()->getPost('destination')

   Expected result

   It should return for the multiselect all options selected

Actual result

It always returns one option

[TomashKhamlai]

Hello! Thank you for reporting. Please provide the whole code of your controller.

When I tried to reproduce your issue I got this:

Here is my code: Webkul.zip

Please check if the problem is actual for you.

[shifra123]

@TomashKhamlai Thank for responding, Just added your code to my project and seems like the error still exist for me

[TomashKhamlai]

Reproducible on 2.1.5, 2.1.6 and latest at this moment 2.1.7. Not reproducible on 2.2.0 (GitHub branch develop). Internal ticket MAGETWO-71177 was created to address this issue.

[magento-engcom-team]

@shifra123, thank you for your report. The issue is already fixed in 2.2.0