How to search a column that I added in Laravel Yajra Datatables with a relationship?

So i am using Yajra Datatables to make my datatable.

I have added a additional column like below so it can show the users name from a relationship.

->addColumn('customer_name', function (Order $order){
                return $order->user->name;
            })

Although this column appears in the datatable I am unable to search it. Below is the full function code:

public function viewDTPending(){
        $store= Auth::user()->store;
        $pending = Order::where('store', $store)->where('status', 'Pending')->orderBy('user_id')->groupBy('order_id', 'status', 'order_branch', 'user_id', 'created_at', 'updated_at');
        return Datatables::of($pending)
            ->addColumn('customer_name', function (Order $order){
                return $order->user->name;
            })
            ->editColumn('created_at', function (Order $order){
                    return $order->created_at->diffForHumans();
                })
            ->make(true);
    }

And below is the ajax code:

<script>
    $(function() {
        $('#table').DataTable({
            processing: true,
            serverSide: true,
            ajax: '{{ url('getPendingOrdersDT') }}',
            columns: [
                { data: 'order_id', name: 'order_id' },
                { data: 'user_id', name: 'user_id' },
                { data: 'customer_name', name: 'customer_name' },
                { data: 'status', name: 'status' }
            ]
        });
    });
</script>

How could i get it to search the customer_name column?

Try Eager loading :

$pending = Order::with('user:id,name')->where('store', $store)->where('status', 'Pending')->orderBy('user_id')->groupBy('order_id', 'status', 'order_branch', 'user_id', 'created_at', 'updated_at');
   return Datatables::of($pending)
     ->addColumn('customer_name', function ($row){
          return $row->user['name'];
   })