Intuit Partner Platform - Can't add an invoice because Item ID is unknown

Question

I am trying to insert an invoice via IPP into a blank Quickbooks store. The insert will always fail because the Item's ID for the Invoice line item does not exist. I have been trying multiple paths to code around this with no success. I thought I could query for the Items and if it cannot find the one I am looking for It will create it. I cannot seem to get this to work. Can I just build an Invoice with a new Item I have created?

I currently build the invoice like this: (the problem is the line that starts with "object[] invoiceItemValues") Intuit.Ipp.Data.Qbd.InvoiceHeader invoiceHeader = new Intuit.Ipp.Data.Qbd.InvoiceHeader(); invoiceHeader.ARAccountName = "Accounts Receivable"; invoiceHeader.BillAddr = physicalAddress; invoiceHeader.CustomerName = customer.Name; invoiceHeader.DocNumber = (invoiceMaxId).ToString().PadLeft(4, '0'); invoiceHeader.TaxAmt = salesTax; invoiceHeader.TotalAmt = amount;

        List<Intuit.Ipp.Data.Qbd.InvoiceLine> listLine = new List<Intuit.Ipp.Data.Qbd.InvoiceLine>();


        Intuit.Ipp.Data.Qbd.ItemsChoiceType2[] invoiceItemAttributes = { Intuit.Ipp.Data.Qbd.ItemsChoiceType2.ItemId, Intuit.Ipp.Data.Qbd.ItemsChoiceType2.UnitPrice, Intuit.Ipp.Data.Qbd.ItemsChoiceType2.Qty };
        object[] invoiceItemValues = { new Intuit.Ipp.Data.Qbd.IdType() { idDomain = Intuit.Ipp.Data.Qbd.idDomainEnum.QB, Value = "2" }, amount, new decimal(1) };



        var invoiceLine = new Intuit.Ipp.Data.Qbd.InvoiceLine();
        invoiceLine.Amount = amount;
        invoiceLine.AmountSpecified = true;
        invoiceLine.Desc = "test " + date.ToShortDateString(); // TODO: This will need to hold the additional fields
        invoiceLine.ItemsElementName = invoiceItemAttributes;
        invoiceLine.Items = invoiceItemValues;
        invoiceLine.ServiceDate = date;
        invoiceLine.ServiceDateSpecified = true;
        listLine.Add(invoiceLine);

        Intuit.Ipp.Data.Qbd.Invoice invoice = new Intuit.Ipp.Data.Qbd.Invoice();
        invoice.Header = invoiceHeader;
        invoice.Line = listLine.ToArray();

This is the error I get: "Validation for txn_line_rec.item_id INVALID key = 30 domain=QB enum = Item"

Here is what tries to query Items, but also requires IDs.

ItemQuery qbdItemQuery = new ItemQuery();
qbdItemQuery.Items = new object[] { new IdSet() { Id = new IdType[] { new IdType() { idDomain = idDomainEnum.NG, Value = "79841" } } } };
qbdItemQuery.ItemsElementName = new ItemsChoiceType4[] { ItemsChoiceType4.ListIdSet };
List<Item> ItemQueryResult = qbdItemQuery.ExecuteQuery<Item>(context).ToList<Item>();

Answer 1

Please see the sample in QBO, similarly you can code for QBD- Intuit.Ipp.Data.Qbo.Invoice invoice = new Intuit.Ipp.Data.Qbo.Invoice();

Intuit.Ipp.Data.Qbo.InvoiceHeader invoiceHeader = new     Intuit.Ipp.Data.Qbo.InvoiceHeader();
invoiceHeader.DocNumber = "AUTO_GENERATE";
invoiceHeader.TxnDate = new DateTime(2013, 09, 04);
invoiceHeader.TxnDateSpecified = true;
invoiceHeader.CustomerId = new Intuit.Ipp.Data.Qbo.IdType() { idDomain =     Intuit.Ipp.Data.Qbo.idDomainEnum.QBO, Value = "12" };
invoiceHeader.SubTotalAmt = 100;
invoiceHeader.SubTotalAmtSpecified = true;
invoiceHeader.TotalAmt = 100;
invoiceHeader.TotalAmtSpecified = true;

invoice.Header = invoiceHeader;

Intuit.Ipp.Data.Qbo.InvoiceLine invoiceLine = new Intuit.Ipp.Data.Qbo.InvoiceLine();
invoiceLine.Desc = "Description";
invoiceLine.Amount = 100;
invoiceLine.AmountSpecified = true;
invoiceLine.Taxable = false;
invoiceLine.TaxableSpecified = true;
invoiceLine.ItemsElementName = new Intuit.Ipp.Data.Qbo.ItemsChoiceType2[] {     Intuit.Ipp.Data.Qbo.ItemsChoiceType2.ItemId,     Intuit.Ipp.Data.Qbo.ItemsChoiceType2.UnitPrice, Intuit.Ipp.Data.Qbo.ItemsChoiceType2.Qty };
invoiceLine.Items = new object[] { new Intuit.Ipp.Data.Qbo.IdType() { idDomain = Intuit.Ipp.Data.Qbo.idDomainEnum.QBO, Value = "30" }, 100m, 1m };

invoice.Line = new Intuit.Ipp.Data.Qbo.InvoiceLine[] { invoiceLine };

Intuit.Ipp.Data.Qbo.Invoice addedInvoice = dataService.Add<Intuit.Ipp.Data.Qbo.Invoice>(invoice);

Edit: To create item-

Intuit.Ipp.Data.Qbo.Item qboItem = new Intuit.Ipp.Data.Qbo.Item();                          
                        qboItem.Name = "nemoitem11";
                        qboItem.Desc = "Itemdesc";
                        qboItem.UnitPrice = new Money() ;
                        qboItem.UnitPrice.Amount = 20;
                        qboItem.IncomeAccountRef = new AccountRef();
                        qboItem.IncomeAccountRef.AccountId = new IdType() { idDomain = idDomainEnum.QBO, Value = "1" };
                        Item resultItem = commonService.Add(qboItem) as Item;