edit calling created_by method in contractor controller

app/Http/Controllers/Contractor/WorkOrderController.php

@@ -614,7 +614,7 @@ class WorkOrderController extends Controller
 			$product = $product->package_name;
 		}
 
-		$created_by = Staff::with('StaffDetail')->find($wo->created_by)->first(); 
+		$created_by = Staff::with('StaffDetail')->where("_id",$wo->created_by)->first();
 		if(empty($created_by)){
 			$created_by = '';
 		}
@@ -639,7 +639,6 @@ class WorkOrderController extends Controller
 
 		}
 
-
         $pdf = PDF::loadView('pdf.workorder-pdf',compact('wo','form','product','created_at','created_by','address'));
         $pdf->setPaper('A4', 'potrait');
         return $pdf->stream();