<?php
$c = \Modules\ApprovalWorkflow\Models\ApprovalChain::where('approvable_type', \Modules\MaterialLogistics\Models\PurchaseOrder::class)->first();
if ($c) {
    if (method_exists($c->approvable, 'items')) {
        $c->approvable->load('items');
        $c->approvable->append('total_cost');
    }
    echo json_encode($c->approvable->toArray(), JSON_PRETTY_PRINT);
} else {
    echo "No PO found.";
}