I have experienced this kind of problem. The error was
PHP Warning – yii\base\ErrorException
htmlspecialchars() expects parameter 1 to be string, object given
what I did was transfer the function in the model like this.
function functionName($data) {
return Lookup::item("SubjectType", $data->subject_type);
},
and then in your view.php file..
[
'label'=>'subject_type',
'value'=>$model->functionName($data),
],