SyteLine IDO Extension Class Method Generator (C#)

using System;
using Mongoose.IDO;
using Mongoose.IDO.Protocol;

namespace Netray.SyteLine.Ext
{
    [IDOExtensionClass("SLItems")]
    public class UETItemsExt : IDOExtensionClass
    {
        // Hand-coded method. Returns 0 on success, non-zero on error.
        // The message for the caller goes in Infobar.
        [IDOMethod(MethodFlags.None, "Infobar")]
        public int GetItemOnHandSummary(string Item, ref string Infobar)
        {
            try
            {
                // Escape single quotes so the value cannot break out of the filter.
                string safeValue = (Item ?? string.Empty).Replace("'", "''");
                string filter = string.Format("Item = N'{0}'", safeValue);

                LoadCollectionResponseData response = this.Context.Commands.LoadCollection(
                    "SLItemWhses",
                    "Item, Whse, QtyOnHand",
                    filter,
                    "Whse",
                    0);

                int sumIndex = response.PropertyList.IndexOf("QtyOnHand");
                decimal total = 0m;
                int rows = 0;

                foreach (IDOItem item in response.Items)
                {
                    if (!item.PropertyValues[sumIndex].IsNull)
                    {
                        total += item.PropertyValues[sumIndex].GetValue<decimal>();
                    }
                    rows++;
                }

                Infobar = string.Format("{0} rows from SLItemWhses, total QtyOnHand {1}", rows, total);
                return 0;
            }
            catch (Exception ex)
            {
                Infobar = ex.Message;
                return 16;
            }
        }
    }
}

// Same load written with LoadCollectionRequestData, useful when you
// build the property list or filter step by step.
LoadCollectionRequestData request = new LoadCollectionRequestData();
request.IDOName = "SLItemWhses";
request.PropertyList.SetProperties("Item, Whse, QtyOnHand");
request.Filter = filter;
request.OrderBy = "Whse";
request.RecordCap = 0;

LoadCollectionResponseData response = this.Context.Commands.LoadCollection(request);

// Read a value by row and property name instead of by index:
// decimal first = response[0, "QtyOnHand"].GetValue<decimal>();

// Deployment checklist for UETItemsExt on SLItems
// 1. Create a .NET Framework class library project and reference the Mongoose
//    framework assemblies from your SyteLine server install (the assemblies that
//    contain the Mongoose.IDO and Mongoose.IDO.Protocol namespaces). Target the
//    same .NET Framework version as the installed framework.
// 2. Build in Release and keep the DLL name stable, for example Netray.SyteLine.Ext.dll.
// 3. Import the DLL on the IDO Custom Assemblies form.
// 4. Open the SLItems IDO in IDO metadata (or your UET extension IDO), set
//    Custom Assembly Name to the imported assembly and Ext Class Name to
//    Netray.SyteLine.Ext.UETItemsExt.
// 5. Add method GetItemOnHandSummary as a hand-coded method with parameters
//    Item (input) and Infobar (input/output, message).
// 6. Unload or refresh IDO metadata on the application server, then test the
//    method from a form event or the IDO method call in a test configuration.