Vtiger. API create PurchaseOrder - php

Question

There is a problem over which I am puzzling for the second day.
$purchaseOrders = new PurchaseOrder();
$lists = new ItemLists();
$lists->productid->set(201);
$lists->hdnGrandTotal->set($balance);
$lists->hdnSubTotal->set($balance);
$lists->quantity->set(1);
$lists->listprice->set($balance);
$arrayDataLineItems = [];
$arrayDataLineItems[] = $lists;
$purchaseOrders->dataLineItems->set($arrayDataLineItems);
$purchaseOrders->subject->set($data['caseId']);
$purchaseOrders->purchaseorderNo->set('PO');
$purchaseOrders->vendorid->set($getVendor->id->getCrmValue());
$purchaseOrders->postatus->set('Created');
$purchaseOrders->bill_street->set($getVendor->street->getCrmValue());
$purchaseOrders->ship_street->set($getVendor->street->getCrmValue());
$purchaseOrders->productid->set(201);
$purchaseOrders->balance->set($balance);
$purchaseOrders->assignedUserId->set(6);
$purchaseOrders->conversion_rate->set(1);
$purchaseOrders->currency_id->set('21x1');
$purchaseOrders->hdnTaxType->set('group');
$purchaseOrders->terms_conditions->set('SEE FULL TERMS OF SERVICE AT https://www.salvagedata.com/about/service-terms/');
$valueMapPurchase = $purchaseOrders->toCrmMap();
$crmPurchase = $api->doCreate(PurchaseOrder::getModuleName(),$valueMapPurchase);
There is such a code. It does not add a PurchaseOrder and does not even return any errors. When I do an error check, it returns just Null. Please help, nothing in my head does not climb as it could be corrected.
Now i have database mysql 5.6

Answer 1

Try something like this:
$po = Vtiger_Record_Model::getCleanInstance('PurchaseOrder');
$po->set('subject', 'my po');
$po->set('assigned_user_id', 1);
//set other variables as needed...
$po->save();