radioButtonGroup doesn't send value in ajax validation

[liviuk2]

Prerequisites

• [x] I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• [x] The issue still exists against the latest master branch of yii2-widget-activeform.
• [x] This is not an usage question. I confirm having gone through and read the documentation for ActiveForm and ActiveField.
• [x] This is not a general programming / coding question. (Those should be directed to the webtips Q & A forum).
• [x] I have attempted to find the simplest possible steps to reproduce the issue.
• [ ] I have included a failing test as a pull request (Optional).

Steps to reproduce the issue

1. Create an ActiveForm

2. Add a field of kind radioButtonGroup

   $form->field($model, 'attribute_name')->radioButtonGroup([1 => 'Active', 2 => 'Second Option', 3 => 'Disabled']);

3. Enable the ajax validation adding php 'enableAjaxValidation' => true to the options of the ActiveForm

Expected behavior and actual behavior

When I follow those steps, looking into the parameters of the ajax request for validation I see the value of the 'attribute_name' always empty.

I was expecting the actual value of the selected option of the `radioButtonGroup

Environment

Browsers

• [x] Google Chrome
• [ ] Mozilla Firefox
• [ ] Internet Explorer
• [ ] Safari

Operating System

• [ ] Windows
• [x] Mac OS X
• [ ] Linux
• [ ] Mobile

Libraries

• jQuery version: v2.2.4
• yii2-widget-activeform version: 1.4.8

Isolating the problem

• [ ] This bug happens on the demos page
• [ ] The bug happens consistently across all tested browsers
• [x] This bug happens when using yii2-widget-activeform without other plugins.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.