Error when clicking filter icon for GridViewComboBoxColumn

[Anumeha]

I have a GridView with a GridViewComboBoxColumn for choosing units of measure.  My grid is bound to a DataTable of parts data.  One of the fields for a part is 'unit of measure' but it is not a required field.  I am using the Excel-like filtering. If I have a null value in the 'unit of measure' field and I click the filter icon, I get an exception that says: "Object reference not set to an instance of an object.".  This only happens when I have a null value for that field in one or more rows. Here is part of the stack trace that seems to indicate that the error happens during the attempt to get the column's distinct values.

A first chance exception of type 'System.NullReferenceException' occurred in Telerik.WinControls.GridView.dll System.NullReferenceException: Object reference not set to an instance of an object.
at Telerik.WinControls.UI.RadListFilterMenuProvider.GetDistinctValuesTable(GridViewDataColumn column)
at Telerik.WinControls.UI.RadListFilterMenuProvider.CreateListFilterMenuItems()
at Telerik.WinControls.UI.RadListFilterMenuProvider.CreateFilterMenu()
at Telerik.WinControls.UI.GridHeaderCellElement.FilterFunctionButton_Click(Object sender, EventArgs e)...

Should I be able to have null values in a field bound to a GridViewComboBoxColumn and expect filtering to work properly?

Here are the properties I have set on the grid:

gridCatalog.AllowCellContextMenu = false;
gridCatalog.AllowDeleteRow = false;
gridCatalog.AutoGenerateColumns = false;
gridCatalog.EnableFiltering = true;
gridCatalog.EnableGrouping = false;
gridCatalog.NewRowEnterKeyMode = RadGridViewNewRowEnterKeyMode.EnterMovesToNextCell;
gridCatalog.EnableCustomSorting = false;
gridCatalog.EnableSorting = true;
gridCatalog.MasterTemplate.SelectLastAddedRow = false;
gridCatalog.MasterTemplate.EnableCustomSorting = false;
gridCatalog.MasterTemplate.EnableSorting = true;
gridCatalog.MasterTemplate.ShowHeaderCellButtons = true;
gridCatalog.MasterTemplate.ShowFilteringRow = false;

I am creating the column like this:

var UOMs = from a in dc.vw_UnitOfMeasureLUs
           orderby a.UnitOfMeasureName
           select a;
GridViewComboBoxColumn colUOM = new GridViewComboBoxColumn();
colUOM.DisplayMember = "UnitOfMeasureName";
colUOM.ValueMember = "UnitOfMeasureID";
colUOM.FieldName = "UnitOfMeasureID";
colUOM.Name = "UnitOfMeasure";
colUOM.HeaderText = "UOM";
colUOM.Width = 80;
colUOM.DataSource = UOMs;
colUOM.DropDownStyle = Telerik.WinControls.RadDropDownStyle.DropDownList;
gridCatalog.MasterTemplate.Columns.Add(colUOM);

Am I doing something wrong or is this expected behavior? 

I would appreciate any help anyone out there has to offer.

Thanks

[Richard Slade]

Hello,

I have tried out adding a combo column and excel like filtering against a null value and I haven't been able to replicate your issue,
I have prepared a small sample for you to try out. Please can you paste this into a new project and give it a try

Designer File

namespace RadGridView_Basic_C
{
    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.radGridView1 = new Telerik.WinControls.UI.RadGridView();
            this.radSpinEditor1 = new Telerik.WinControls.UI.RadSpinEditor();
            ((System.ComponentModel.ISupportInitialize)(this.radGridView1)).BeginInit();
            ((System.ComponentModel.ISupportInitialize)(this.radSpinEditor1)).BeginInit();
            this.SuspendLayout();
            //
            // radGridView1
            //
            this.radGridView1.Location = new System.Drawing.Point(0, 0);
            this.radGridView1.Name = "radGridView1";
            this.radGridView1.Size = new System.Drawing.Size(457, 510);
            this.radGridView1.TabIndex = 0;
            this.radGridView1.Text = "radGridView1";
            //
            // radSpinEditor1
            //
            this.radSpinEditor1.Location = new System.Drawing.Point(196, 517);
            this.radSpinEditor1.Maximum = new decimal(new int[] {
            999999,
            0,
            0,
            131072});
            this.radSpinEditor1.Name = "radSpinEditor1";
            //
            //
            //
            this.radSpinEditor1.RootElement.AutoSizeMode = Telerik.WinControls.RadAutoSizeMode.WrapAroundChildren;
            this.radSpinEditor1.ShowBorder = true;
            this.radSpinEditor1.Size = new System.Drawing.Size(100, 21);
            this.radSpinEditor1.TabIndex = 1;
            this.radSpinEditor1.TabStop = false;
            //
            // Form1
            //
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(457, 556);
            this.Controls.Add(this.radSpinEditor1);
            this.Controls.Add(this.radGridView1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.Form1_Load);
            ((System.ComponentModel.ISupportInitialize)(this.radGridView1)).EndInit();
            ((System.ComponentModel.ISupportInitialize)(this.radSpinEditor1)).EndInit();
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private Telerik.WinControls.UI.RadGridView radGridView1;
        private Telerik.WinControls.UI.RadSpinEditor radSpinEditor1;
    }
}

Form1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Telerik.WinControls.UI;
using Telerik.WinControls;
using Telerik.WinControls.Data;
using System.Globalization;


namespace RadGridView_Basic_C
{
    public partial class Form1 : Form
    {

        private List<MyDataType> m_myList = new List<MyDataType>();


        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            this.radGridView1.AutoGenerateColumns = false;
            this.radGridView1.ShowFilteringRow = false;
            this.radGridView1.ShowHeaderCellButtons = true;
            this.radGridView1.EnableFiltering = true;
            this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

            m_myList.Add(new MyDataType(1, "10"));
            m_myList.Add(new MyDataType(2, "20"));
            m_myList.Add(new MyDataType(3, "30"));
            m_myList.Add(new MyDataType(4, null));
            radGridView1.DataSource = m_myList;

            GridViewDecimalColumn int1Column = new GridViewDecimalColumn();
            int1Column.Name = "Int1";
            int1Column.HeaderText = "Int1";
            int1Column.FieldName = "Int1";
            this.radGridView1.Columns.Add(int1Column);

            GridViewComboBoxColumn comboColumn = new GridViewComboBoxColumn();
            comboColumn.Name = "UnitOfMeasure";
            comboColumn.HeaderText = "UnitOfMeasure";
            comboColumn.FieldName = "UnitOfMeasure";
            this.radGridView1.Columns.Add(comboColumn);

            List<UnitOfMeasure> UOM = new List<UnitOfMeasure>();
            UOM.Add(new UnitOfMeasure("10"));
            UOM.Add(new UnitOfMeasure("20"));
            UOM.Add(new UnitOfMeasure("30"));
            UOM.Add(new UnitOfMeasure("40"));
            comboColumn.DataSource = UOM;
            comboColumn.DisplayMember = "UOM";
            comboColumn.ValueMember = "UOM";

            radGridView1.DataSource = m_myList;

        }





        class MyDataType
        {
            public MyDataType()
            { }

            public MyDataType(decimal int1, string uom)
            {
                this.Int1 = int1;
                this.UnitOfMeasure = uom;
            }

            public decimal Int1 { get; set; }
            public string UnitOfMeasure { get; set; }

        }

        class UnitOfMeasure
        {
            public UnitOfMeasure()
            { }

            public UnitOfMeasure(string uom)
            {
                this.UOM = uom;
            }

            public string UOM { get; set; }

        }


    }

 }

Let me know if that helps
Thanks
Richard

[Anumeha]

Thanks for the quick reply Richard.  I have tested your code and it does not throw the error when I click the filter icon.  However, our UOM table has an ID column and a Name column.  I set my combobox column's ValueMember to the UOMID field and the column's DisplayField to the UOMName.  When the combobox includes the UOMID field I get an error when I click the filter icon.  Here is the updated code:

public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
    }
    private void Form2_Load(object sender, EventArgs e)
    {
        this.radGridView1.AutoGenerateColumns = false;
        this.radGridView1.ShowFilteringRow = false;
        this.radGridView1.ShowHeaderCellButtons = true;
        this.radGridView1.EnableFiltering = true;
        this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
        GridViewTextBoxColumn colPartNumber = new GridViewTextBoxColumn("PartNumber", "PartNumber");
        colPartNumber.HeaderText = "PartNumber";
        colPartNumber.Width = 100;
        radGridView1.MasterTemplate.Columns.Add(colPartNumber);
        GridViewComboBoxColumn comboColumn = new GridViewComboBoxColumn();
        comboColumn.Name = "UnitOfMeasure";
        comboColumn.HeaderText = "UnitOfMeasure";
        comboColumn.FieldName = "UOMID";
        comboColumn.DataSource = GetUOMTable();
        comboColumn.DisplayMember = "UOMName";
        comboColumn.ValueMember = "UOMID";
        radGridView1.MasterTemplate.Columns.Add(comboColumn);
        radGridView1.DataSource = GetPartsTable();
    }
    private DataTable GetPartsTable()
    {
        int? nullableint = 0;
        DataTable dt = new DataTable();
        DataColumn dcPartNumber = new DataColumn("PartNumber", typeof(string));
        DataColumn dcUOMID = new DataColumn("UOMID", nullableint.GetType());

        dt.Columns.Add(dcPartNumber);
        dt.Columns.Add(dcUOMID);

        DataRow row = dt.NewRow();
        row["PartNumber"] = "Part 1";
        row["UOMID"] = 1;
        dt.Rows.Add(row);
        DataRow row2 = dt.NewRow();
        row2["PartNumber"] = "Part 2";
        row2["UOMID"] = DBNull.Value;
        dt.Rows.Add(row2);
        return dt;
    }
    private DataTable GetUOMTable()
    {
        DataTable dt = new DataTable();
        DataColumn dcUOMID = new DataColumn("UOMID", typeof(int));
        DataColumn dcUOMName = new DataColumn("UOMName", typeof(string));
        dt.Columns.Add(dcUOMID);
        dt.Columns.Add(dcUOMName);
        DataRow row = dt.NewRow();
        row["UOMID"] = 1;
        row["UOMName"] = "Each";
        dt.Rows.Add(row);
        DataRow row2 = dt.NewRow();
        row2["UOMID"] = 2;
        row2["UOMName"] = "Feet";
        dt.Rows.Add(row2);
        return dt;
    }
}

Thanks again for your help.

[Richard Slade]

Hi,

Sorry for the delayed reply. I think we must be on different timezones. I haven't run your code yet as I'm not at my development environment (I'll do that as soon as I can and let you know the results). I have looked through the Public Issue Tracking System though to see if there is already a bug that reports this issue. I couldn't find one that is teh same, though it may be the same one as this.

I'll run your code and let you know as soon as I can. In the meantime, please can you confirm which version of RadControls you are using.
Thanks
Richard

[Richard Slade]

Hello,

I've had a look at your code and unless I'm missing something as well, I think that the filter should be able to handle the DBNull value. This should be picked up by the Telerik team that will be able to confirm (or deny) this. If it's the case that this is a bug, then I would expect that
Regards,
Richard

[Anumeha]

Thanks for looking at the code Richard.  I agree that it looks like it should be ok but it does end up throwing an error when I click the filter icon.  I don't even get a chance to choose any of the filtering options.  If no one is able to replicate the issue I can submit a support ticket and attach the project.

Thanks

[Richard Slade]

Hi,

Apologies if I wasn't clear. Yes, your code looks fine, and yes, I can replicate your issue. Telerik staff are usually very good at keeping an eye on forum posts and it is highly likely that they may have seen this and may be investigating it. However, it may be worth opening a support ticket and Telerik always appreciate it if you can attach a sample project. If you open a support ticket, please also quote this forum link so it's easy for them to track all references to the issue.

hope that helps, but if you need anything else, just let me know.
Regards,
Richard

[Martin Vasilev]

Hello guys,

I managed to reproduce the described exception. It is caused because of an omission in our method of getting distinct values if there is a DBNull type in the column. We will address this issue in the next release. I am adding this issue in our public bug tracking system (PITS)

Anumeha, I have updated your Telerik points for bringing our attention to this issue. Do not hesitate to contact us again if you have any other questions.

Kind regards,
Martin Vasilev
the Telerik team