protected function guessColumns()
{
$models = $this->dataProvider->getModels();
$model = reset($models);
if (is_array($model) || is_object($model)) {
foreach ($model as $name => $value) {
if ($value === null || is_scalar($value) || is_callable([$value, '__toString'])) {
$this->columns[] = (string) $name;
}
}
}
}