How to update radio group status in a metabox? - php

Question

I have implemented radio-group option in WordPress metabox. I got the desire radio group in meta box with respective label, but I failed to update my checked status on selecting radio or saving the post where I am using it. I think there is something I need to put.
<div class="my radio group">
<h2>my radio group </h2>
<?php
$cars = array('BMW', 'FERRARI', 'PORSCHE', 'BENTALI', 'MRX', 'CHEVROLET');
foreach ($cars as $car) {
echo '<input name="my-best-car" type="radio" onchange="javascript:document.post.submit()"';
$option = 'id=" ' .$car . '"';
$option = '<value="' . $car . '"';
if ($car == $my_favorite_car) $option .= "checked";
$option .= '>';
$option .= '<label for=" '.$car .' ">' . $car .' ';
$option .= '</label>';
echo $option;
}
?>
</div>
WordPress meta box save function is also added. My other option type like text, select & checkbox updating properly.
While I trying to update my RADIO-GROUP meta values using:
update_post_meta($post_id, 'my-best-car', $_POST['my-best-car'], true);

Answer 1

Ok I found your mistake in foreach loop you have one < extra before the value so the line would look like this:
$option = 'value="' . $car . '"';
Also your js is not submitting the form so just add js function in head like this for example:
<script>
function submitOnClick(formName){
document.forms[formName].submit();
}
</script>
And in the form instead of:
onchange="javascript:document.post.submit()"
put
onclick="submitOnClick(\'myForm\')"
I tried it and it works you just need to rename your form name accordingly