using System;
using System.Collections;
using Telerik.Web.UI;

namespace RadFilterBracketFieldNameRepro
{
    class Program
    {
        private const string BracketedFieldName = "[dataBooking].[TotalPaid]";

        static void Main()
        {
            Console.WriteLine("Telerik.Web.UI version: " + typeof(RadFilter).Assembly.GetName().Version);
            Console.WriteLine("FieldName under test:   " + BracketedFieldName);
            Console.WriteLine();

            // 1) Build a filter with one expression against a bracket-qualified field name.
            //    This format is not unusual -- it's what you get for any field name that needs
            //    to be schema/table-qualified. Telerik's own RadFilterSqlExpressionEvaluator
            //    produces the same "[table].[column]" shape when generating SQL.
            RadFilter source = new RadFilter();
            source.FieldEditors.Add(new RadFilterTextFieldEditor { FieldName = BracketedFieldName });

            RadFilterLessThanFilterExpression<string> expression = new RadFilterLessThanFilterExpression<string>(BracketedFieldName);
            ((IRadFilterValueExpression)expression).SetValues(new ArrayList { "1000" });
            source.RootGroup.AddExpression(expression);

            // 2) Persist it the normal way.
            string savedState = source.SaveSettings();
            Console.WriteLine("SaveSettings() output (base64):");
            Console.WriteLine(savedState);
            Console.WriteLine();
            Console.WriteLine("Decoded JSON:");
            Console.WriteLine(System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(savedState)));
            Console.WriteLine();

            // 3) Simulate the next request restoring that saved state into a fresh RadFilter,
            //    exactly like a report/page reload would.
            RadFilter restored = new RadFilter();
            restored.FieldEditors.Add(new RadFilterTextFieldEditor { FieldName = BracketedFieldName });

            try
            {
                restored.LoadSettings(savedState);

                RadFilterLessThanFilterExpression<string> restoredExpression = (RadFilterLessThanFilterExpression<string>)restored.RootGroup.Expressions[0];

                Console.WriteLine("FieldName after LoadSettings(): '" + restoredExpression.FieldName + "'");
                Console.WriteLine(restoredExpression.FieldName == BracketedFieldName
                    ? "OK -- FieldName round-tripped correctly."
                    : "BUG REPRODUCED -- FieldName was lost during LoadSettings().");
            }
            catch (Exception ex)
            {
                Console.WriteLine("BUG REPRODUCED -- LoadSettings() threw:");
                Console.WriteLine(ex);
            }

            Console.WriteLine();
            Console.WriteLine("Press Enter to exit...");
            Console.ReadLine();
        }
    }
}

System.ArgumentException: Parameter cannot be null or empty.
Parameter name: fieldName
  RadFilterDataFieldEditorCollection.FindEditorForFieldName
  RadFilterSingleExpressionItem.SetupFunctionInterface
  RadFilter.CreateFilterItems / CreateChildControls
  RadFilter.RecreateControl
  RadFilter.LoadSettings