I need to populate the Checkbox Group field, reading from the database, bringing the values with checked, according to the records inside the database.

I managed to do the items and with the checked, but the listing is grouping and I am not able to update/submit the record of that field.

Does anyone know of any documentation on how to poll this field?

my script

//<code>
$items = array();
$db = JFactory::getDbo();
$user = JFactory::getUser();

$query = $db->getQuery(true);
$query->select('a.id, a.title, IF(b.group_id IS NOT NULL, 1, 0) AS checked')
->from($db->quoteName('#__usergroups', 'a'))
->leftJoin($db->quoteName('#__user_usergroup_map', 'b') . ' ON (' . $db->quoteName('a.id') . ' = ' . $db->quoteName('b.group_id') . ' AND ' . $db->quoteName('b.user_id') . ' = ' . $db->quote($user->id) . ')')
->where('a.parent_id IN (16, 17, 24, 27)');

$db->setQuery($query);
$results = $db->loadObjectList();

foreach ($results as $result)
{
$value = $result->id;
$label = $result->title;
$checked = $result->checked ? 'checked' : '';
$items[] = "<input type='checkbox' name='form[assunto-de-interesse][]' class='rsform-checkbox form-check-input' id='assunto-de-interesse{$value}' value='{$value}' {$checked}> <label id='assunto-de-interesse{$value}' for='assunto-de-interesse{$value}' class='form-check-label'>{$label}</label>";
}

$items = implode("<br>", $items);

return $items;
//</code>