AX 2012 Creating, Confirming, Invoicing Purchase Order

static void Esh_CreatePO(Args _args)
{

PurchTable purchTable;
PurchLine purchLine;
VendTable vendTable = VendTable::find("US_TX_001"); //Specify Vendor Account which is nothing but selecting a Purchase Order
AxPurchTable axPurchTable;
AxPurchLine axPurchLine;
PurchFormLetter purchFormLetter;
;

//Create Purchase order
purchTable.initFromVendTable(vendTable);

axPurchTable = axPurchTable::newPurchTable(purchTable);
axPurchTable.parmPurchaseType(PurchaseType::Purch);
axPurchTable.parmDocumentStatus(DocumentStatus::PurchaseOrder);


axPurchTable.parmDeliveryDate(str2date("08/18/2014",213)); // Important because system check the transaction date.
axPurchTable.parmAccountingDate(str2date("08/18/2014",213));
axPurchTable.parmPurchStatus(PurchStatus::Backorder);

axPurchTable.doSave();


purchLine.initFromPurchTable(purchTable);

axPurchLine = AxPurchLine::newPurchLine(purchLine);
axpurchLine.parmItemId("A0001");
axpurchLine.parmInventDimId('000458');//important because Wherhouse, dimension location, dimension inventory status must be specified.
axPurchLine.parmPurchQty(10);
axPurchLine.parmPurchPrice(100);
axPurchLine.doSave();

//PO confirmation 
purchTable = axPurchTable.purchTable();
purchFormLetter = PurchFormLetter::construct(DocumentStatus::PurchaseOrder);
purchFormLetter.update(purchTable, strFmt("Inv_%1", purchTable.PurchId));

// PO invoicing
purchFormLetter = PurchFormLetter::construct(DocumentStatus::Invoice);
purchFormLetter.update(purchTable, strFmt("Inv_%1", purchTable.PurchId));
info(strFmt("purchase order %1 invoiced",purchTable.PurchId));

}