Extracting Production Order Reference into Inventory Lot/Serial History Screen

Thank you ​@aiwan and ​@MichaelShirk for the help. I have taken the suggestions into concern and the code modified below works to pull values specifically for transaction types ‘Issue’ and ‘Receipt’. Please find code below for reference, thank you!

 protected virtual void INTranSplit_RowSelected(PXCache sender, PXRowSelectedEventArgs e)
    {
        if (e.Row == null)
            return;

        var row = (InventoryLotSerInq.INTranSplit)e.Row;

        // Get the extension first
        INTranSplitExt splitRowExt = sender.GetExtension<INTranSplitExt>(row);

        // Only process receipts and issues 
        if (row.DocType != INDocType.Receipt && row.DocType != INDocType.Issue)
        {
            splitRowExt.UsrMAINProdOrdID = null;
            return;
        }

        if (string.IsNullOrEmpty(row.RefNbr) || string.IsNullOrEmpty(row.DocType))
            return;

        PXTrace.WriteInformation($"Processing INTranSplit_RowSelected for DocType: {row.DocType}, RefNbr: {row.RefNbr}");

        try
        {
            string prodOrdID = null;

            if (row.DocType == INDocType.Receipt)
            {
                // Handle receipts 
                prodOrdID = GetProductionOrderFromReceipt(row);
            }
            else if (row.DocType == INDocType.Issue)
            {
                // Handle issues 
                prodOrdID = GetProductionOrderFromIssue(row);
            }

            // Set the production order ID if found
            if (!string.IsNullOrEmpty(prodOrdID))
            {
                splitRowExt.UsrMAINProdOrdID = prodOrdID;
                PXTrace.WriteInformation($"Successfully set UsrMAINProdOrdID to {prodOrdID}");
            }
            else
            {
                splitRowExt.UsrMAINProdOrdID = null;
                PXTrace.WriteInformation("No production order found for this transaction");
            }
        }
        catch (Exception ex)
        {
            PXTrace.WriteError($"Error in INTranSplit_RowSelected: {ex.Message}\n{ex.StackTrace}");
        }
    }

    private string GetProductionOrderFromReceipt(InventoryLotSerInq.INTranSplit row)
    {
        try
        {
            // Get the INRegister for this transaction
            INRegister inRegister = PXSelect<INRegister,
                Where<INRegister.docType, Equal<Required<INRegister.docType>>,
                    And<INRegister.refNbr, Equal<Required<INRegister.refNbr>>>>>
                .Select(Base, row.DocType, row.RefNbr)
                .RowCast<INRegister>()
                .FirstOrDefault();

            if (inRegister == null)
            {
                PXTrace.WriteWarning($"No INRegister found for DocType: {row.DocType}, RefNbr: {row.RefNbr}");
                return null;
            }

            // Get the AMBatNbr from the INRegister extension
            INRegisterExt inRegisterExt = PXCache<INRegister>.GetExtension<INRegisterExt>(inRegister);
            if (inRegisterExt == null)
            {
                PXTrace.WriteWarning("INRegisterExt is null");
                return null;
            }

            string amBatNbr = inRegisterExt.AMBatNbr;
            PXTrace.WriteInformation($"Found INRegister with AMBatNbr: {amBatNbr}");

            if (string.IsNullOrEmpty(amBatNbr))
                return null;

            // Find the AMMTran record using AMBatNbr AND matching InventoryID
            AMMTran amMTran = PXSelect<AMMTran,
                Where<AMMTran.batNbr, Equal<Required<AMMTran.batNbr>>,
                    And<AMMTran.inventoryID, Equal<Required<AMMTran.inventoryID>>>>>
                .Select(Base, amBatNbr, row.InventoryID)
                .RowCast<AMMTran>()
                .FirstOrDefault();

            if (amMTran == null)
            {
                PXTrace.WriteWarning($"No AMMTran found for AMBatNbr: {amBatNbr}, InventoryID: {row.InventoryID}");
                return null;
            }

            PXTrace.WriteInformation($"Found Production Order ID from receipt: {amMTran.ProdOrdID}");
            return amMTran.ProdOrdID;
        }
        catch (Exception ex)
        {
            PXTrace.WriteError($"Error in GetProductionOrderFromReceipt: {ex.Message}");
            return null;
        }
    }

    private string GetProductionOrderFromIssue(InventoryLotSerInq.INTranSplit row)
    {
        try
        {

            // Look for AMMTran records that match this inventory transaction using INBatNbr and INDocType
            AMMTran amMTran = PXSelect<AMMTran,
                Where<AMMTran.inventoryID, Equal<Required<AMMTran.inventoryID>>,
                    And<AMMTran.iNBatNbr, Equal<Required<AMMTran.iNBatNbr>>,
                    And<AMMTran.iNDocType, Equal<Required<AMMTran.iNDocType>>>>>>
                .Select(Base, row.InventoryID, row.RefNbr, row.DocType)
                .RowCast<AMMTran>()
                .FirstOrDefault();

            if (amMTran != null)
            {
                PXTrace.WriteInformation($"Found Production Order ID from issue AMMTran: {amMTran.ProdOrdID}");
                return amMTran.ProdOrdID;
            }

            //Check if the INRegister has manufacturing batch number
            INRegister inRegister = PXSelect<INRegister,
                Where<INRegister.docType, Equal<Required<INRegister.docType>>,
                    And<INRegister.refNbr, Equal<Required<INRegister.refNbr>>>>>
                .Select(Base, row.DocType, row.RefNbr)
                .RowCast<INRegister>()
                .FirstOrDefault();

            if (inRegister != null)
            {
                INRegisterExt inRegisterExt = PXCache<INRegister>.GetExtension<INRegisterExt>(inRegister);
                if (inRegisterExt != null && !string.IsNullOrEmpty(inRegisterExt.AMBatNbr))
                {
                    // Find AMMTran with this batch number
                    AMMTran batchMTran = PXSelect<AMMTran,
                        Where<AMMTran.batNbr, Equal<Required<AMMTran.batNbr>>,
                            And<AMMTran.inventoryID, Equal<Required<AMMTran.inventoryID>>>>>
                        .Select(Base, inRegisterExt.AMBatNbr, row.InventoryID)
                        .RowCast<AMMTran>()
                        .FirstOrDefault();

                    if (batchMTran != null)
                    {
                        PXTrace.WriteInformation($"Found Production Order ID from issue batch: {batchMTran.ProdOrdID}");
                        return batchMTran.ProdOrdID;
                    }
                }
            }

            PXTrace.WriteWarning($"No production order found for issue transaction: {row.RefNbr}");
            return null;
        }
        catch (Exception ex)
        {
            PXTrace.WriteError($"Error in GetProductionOrderFromIssue: {ex.Message}");
            return null;
        }
    }