private function _validateColumn(array $data)
{
if (!isset($data['label'])) {
return 'Label key is required.';
}
if (!isset($data['index'])) {
return 'Index key is required.';
}
if (isset($data['renderer']) && (!$data['renderer'] instanceof \Closure && !is_string($data['renderer']))) {
return 'Renderer must be a string or instance of Closure object.';
}
if (isset($data['filter']) && !$data['filter'] instanceof \Closure) {
return 'Filter function must be instance of Closure object.';
}
return true;
}