public function getSortData()
{
return ['single field without sort' => [['field1'], [['field' => 'field1', 'sort' => 'asc']]], 'single field with sort' => [['field1:desc'], [['field' => 'field1', 'sort' => 'desc']]], 'multiple fields' => [['field1', 'field2:desc', 'field3:asc'], [['field' => 'field1', 'sort' => 'asc'], ['field' => 'field2', 'sort' => 'desc'], ['field' => 'field3', 'sort' => 'asc']]]];
}