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Scrolling through the GridView throws exception

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GridView
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KARTHIK REDDY KAMIDI
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KARTHIK REDDY KAMIDI asked on 23 Feb 2011, 08:43 PM
Hello,

I have a hierarchical GridView with about 250+ rows. Scrolling through the grid page at a time by clicking on the scrollbar throws exception.

      Object reference not set to an instance of an object.
         at Telerik.WinControls.UI.GridTraverser.StepInHierarchyBackward()
         at Telerik.WinControls.UI.GridTraverser.MovePreviousCore()
         at Telerik.WinControls.UI.GridTraverser.MovePrevious()
         at Telerik.WinControls.UI.ItemScroller`1.ScrollUp(Int32 step)
         at Telerik.WinControls.UI.ItemScroller`1.thumbTimer_Tick(Object sender, EventArgs e)
         at System.Windows.Forms.Timer.OnTick(EventArgs e)
         at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
         at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
         at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
         at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
         at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
         at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
         at System.Windows.Forms.Application.Run(Form mainForm)
         at GridSample1.Program.Main() in C:\Users\MyUserName\Documents\GridSample1\Program.cs:line 18
         at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
         at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
         at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
         at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
         at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
         at System.Threading.ThreadHelper.ThreadStart()


My code was working fine until Q2 2010 SP1. My current version is Q3 2010.

Thanks.

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Richard Slade
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answered on 23 Feb 2011, 10:06 PM
Hello again,

I haven't been able to replicate this. Please could you put together a sample that replicates the issue (designer and form) and post the code here using the Format Code block and I'll see if I can replicate it too for you.
Thanks
Richard
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Richard Slade
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answered on 23 Feb 2011, 10:09 PM
Hi,

For reference, I've also looked in PITS and there were no reported issues of this nature at the moment.
Regards,
Richard
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KARTHIK REDDY KAMIDI
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answered on 24 Feb 2011, 11:32 PM
Richard,
Thank you again for looking into another one of my issues. My sample project is also included. The exceptions I get are as follows:

Clicking to scroll:
---------------------------
System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.WinControls.UI.GridTraverser.StepInHierarchyBackward()
   at Telerik.WinControls.UI.GridTraverser.MovePreviousCore()
   at Telerik.WinControls.UI.GridTraverser.MovePrevious()
   at Telerik.WinControls.UI.ItemScroller`1.ScrollUp(Int32 step)
   at Telerik.WinControls.UI.ItemScroller`1.thumbTimer_Tick(Object sender, EventArgs e)
   at System.Windows.Forms.Timer.OnTick(EventArgs e)
   at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Dragging the scrollbar:
---------------------------
System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.WinControls.UI.GridTraverser.StepInHierarchyBackward()
   at Telerik.WinControls.UI.GridTraverser.MovePreviousCore()
   at Telerik.WinControls.UI.GridTraverser.MovePrevious()
   at Telerik.WinControls.UI.ItemScroller`1.ScrollUp(Int32 step)
   at Telerik.WinControls.UI.ItemScroller`1.UpdateOnScroll(ScrollEventArgs e)
   at Telerik.WinControls.UI.ItemScroller`1.scrollbar_Scroll(Object sender, ScrollEventArgs e)
   at Telerik.WinControls.UI.RadScrollBarElement.OnScroll(ScrollEventArgs args)
   at Telerik.WinControls.UI.RadScrollBarElement.CallOnScroll(ScrollEventType scrollType, Int32 oldValue, Int32 newValue)
   at Telerik.WinControls.UI.RadScrollBarElement.ScrollWith(Int32 step, ScrollEventType scrollType)
   at Telerik.WinControls.UI.RadScrollBarElement.OnScrollTimer(Object sender, EventArgs e)
   at Telerik.WinControls.UI.RadScrollBarElement.OnMouseDown(MouseEventArgs e)
   at Telerik.WinControls.RadElement.OnCLREventsRise(RoutedEventArgs args)
   at Telerik.WinControls.RadElement.OnBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.OnBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.DoMouseDown(MouseEventArgs e)
   at Telerik.WinControls.RadElement.CallDoMouseDown(MouseEventArgs e)
   at Telerik.WinControls.ComponentInputBehavior.OnMouseDown(MouseEventArgs e)
   at Telerik.WinControls.RadControl.OnMouseDown(MouseEventArgs e)
   at Telerik.WinControls.UI.RadGridView.OnMouseDown(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
 
namespace GridSample1
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
 
            Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(Application_ThreadException);
            AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException);
 
            Application.Run(new Form1());
        }
 
        static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
        {
            MessageBox.Show(e.ExceptionObject.ToString());
        }
 
        static void Application_ThreadException(object sender, System.Threading.ThreadExceptionEventArgs e)
        {
            MessageBox.Show(e.Exception.ToString());
        }
    }
}
 
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;
 
namespace GridSample1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
            this.propertiesControl1.LoadVariables();
        }
    }
}
 
namespace GridSample1
{
    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;
 
        /// <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.propertiesControl1 = new GridSample1.PropertiesControl();
            this.SuspendLayout();
            //
            // propertiesControl1
            //
            this.propertiesControl1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
                        | System.Windows.Forms.AnchorStyles.Left)
                        | System.Windows.Forms.AnchorStyles.Right)));
            this.propertiesControl1.Location = new System.Drawing.Point(13, 13);
            this.propertiesControl1.Name = "propertiesControl1";
            this.propertiesControl1.Size = new System.Drawing.Size(532, 475);
            this.propertiesControl1.TabIndex = 0;
            //
            // Form1
            //
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(557, 500);
            this.Controls.Add(this.propertiesControl1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.ResumeLayout(false);
 
        }
 
        #endregion
 
        private PropertiesControl propertiesControl1;
    }
}
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace GridSample1
{
    public class Model
    {
        public Model() { }
 
        public Model(string id, string parentId, string name, string value, string units)
        { this.Id = id; this.ParentId = parentId; this.Name = name; this.Value = value; this.Units = units; }
 
        public string Id
        { get; set; }
 
        public string ParentId
        { get; set; }
 
        public string Name
        { get; set; }
 
        public string Value
        { get; set; }
 
        public string Units
        { get; set; }
 
 
        public static List<Model> GetDummyModelList()
        {
            var list = new List<Model>
            {
                new Model("885", "G63", "Item 2", "Value 2", ""),
                new Model("900", "G63", "Item 3", "Value 3", ""),
                new Model("903", "G63", "Item 4", "Value 4", ""),
                new Model("886", "G63", "Item 5", "Value 5", "Unit 5"),
                new Model("896", "G63", "Item 6", "Value 6", ""),
                new Model("897", "G63", "Item 7", "Value 7", ""),
                new Model("901", "G63", "Item 8", "Value 8", ""),
                new Model("902", "G63", "Item 9", "Value 9", ""),
                new Model("890", "G63", "Item 10", "Value 10", ""),
                new Model("893", "G63", "Item 11", "Value 11", ""),
                new Model("913", "G63", "Item 12", "Value 12", "Unit 12"),
                new Model("914", "G63", "Item 13", "Value 13", "Unit 13"),
                new Model("895", "G63", "Item 14", "Value 14", "Unit 14"),
                new Model("892", "G63", "Item 15", "Value 15", "Unit 15"),
                new Model("894", "G63", "Item 16", "Value 16", ""),
                new Model("891", "G63", "Item 17", "Value 17", "Unit 17"),
                new Model("898", "G63", "Item 18", "Value 18", ""),
                new Model("889", "G63", "Item 19", "Value 19", "Unit 19"),
                new Model("887", "G63", "Item 20", "Value 20", "Unit 20"),
                new Model("888", "G63", "Item 21", "Value 21", "Unit 21"),
                new Model("904", "G63", "Item 22", "Value 22", ""),
                new Model("907", "G63", "Item 23", "Value 23", ""),
                new Model("915", "G63", "Item 24", "Value 24", ""),
                new Model("908", "G63", "Item 25", "Value 25", ""),
                new Model("911", "G63", "Item 26", "Value 26", ""),
                new Model("906", "G63", "Item 27", "Value 27", ""),
                new Model("909", "G63", "Item 28", "Value 28", ""),
                new Model("910", "G63", "Item 29", "Value 29", ""),
                new Model("899", "G63", "Item 30", "Value 30", ""),
                new Model("912", "G63", "Item 31", "Value 31", ""),
                new Model("905", "G63", "Item 32", "Value 32", ""),
                new Model("G63", "", "Group 1", "", ""),
                new Model("925", "G364", "Item 33", "Value 33", ""),
                new Model("926", "G364", "Item 34", "Value 34", ""),
                new Model("G364", "", "Group 2", "", "")
            };
            return list;
        }
    }
}
 
 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Telerik.WinControls.UI;
using System.Diagnostics;
 
namespace GridSample1
{
    public partial class PropertiesControl : UserControl
    {
        Stopwatch stopwatch = new Stopwatch();
 
        public PropertiesControl()
        {
            InitializeComponent();
 
            stopwatch.Start();
 
            SetupRadGridviewRelation();
        }
 
        private void SetupRadGridviewRelation()
        {
            GridViewRelation selfRelation = new GridViewRelation(this.radGridView1.MasterTemplate, this.radGridView1.MasterTemplate);
            selfRelation.ParentColumnNames.Add("IdCol");
            selfRelation.ChildColumnNames.Add("ParentIdCol");
            this.radGridView1.Relations.Add(selfRelation);
        }
 
        public void LoadVariables()
        {
            var mboxCount = 0;
 
            var list = Model.GetDummyModelList();
 
            using (this.radGridView1.DeferRefresh())
            {
                radGridView1.Rows.Clear();
 
                foreach (var item in list)
                {
                    var rowNum = radGridView1.Rows.Add(item.Id, item.ParentId, item.Name, item.Value, item.Units);
                    if (rowNum < 0)
                        ++mboxCount;
                    else
                        radGridView1.Rows[rowNum].Tag = item;
                }
            }
 
            ExpandRows();
 
            if (mboxCount > 0)
                MessageBox.Show("Row num was -ve for " + mboxCount + " rows, out of " + list.Count);
            else
                MessageBox.Show("Added " + list.Count + " rows");
 
            stopwatch.Stop();
        }
 
        private void ExpandRows()
        {
            using (this.radGridView1.DeferRefresh())
            {
                foreach (var childRow in radGridView1.ChildRows)
                {
                    childRow.IsExpanded = true;
                    foreach (var childChildRow in childRow.ChildRows)
                    {
                        childChildRow.IsExpanded = true;
                        foreach (var childChildChildRow in childChildRow.ChildRows)
                        {
                            childChildChildRow.IsExpanded = true;
                        }
                    }
                }
            }
        }
    }
}
 
 
namespace GridSample1
{
    partial class PropertiesControl
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;
 
        /// <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 Component 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()
        {
            Telerik.WinControls.UI.GridViewTextBoxColumn gridViewTextBoxColumn1 = new Telerik.WinControls.UI.GridViewTextBoxColumn();
            Telerik.WinControls.UI.GridViewTextBoxColumn gridViewTextBoxColumn2 = new Telerik.WinControls.UI.GridViewTextBoxColumn();
            Telerik.WinControls.UI.GridViewTextBoxColumn gridViewTextBoxColumn3 = new Telerik.WinControls.UI.GridViewTextBoxColumn();
            Telerik.WinControls.UI.GridViewTextBoxColumn gridViewTextBoxColumn4 = new Telerik.WinControls.UI.GridViewTextBoxColumn();
            Telerik.WinControls.UI.GridViewTextBoxColumn gridViewTextBoxColumn5 = new Telerik.WinControls.UI.GridViewTextBoxColumn();
            this.radGridView1 = new Telerik.WinControls.UI.RadGridView();
            ((System.ComponentModel.ISupportInitialize)(this.radGridView1)).BeginInit();
            this.SuspendLayout();
            //
            // radGridView1
            //
            this.radGridView1.Dock = System.Windows.Forms.DockStyle.Fill;
            this.radGridView1.Location = new System.Drawing.Point(0, 0);
            //
            //
            //
            this.radGridView1.MasterTemplate.AllowAddNewRow = false;
            this.radGridView1.MasterTemplate.AllowColumnChooser = false;
            this.radGridView1.MasterTemplate.AllowColumnReorder = false;
            this.radGridView1.MasterTemplate.AllowDeleteRow = false;
            this.radGridView1.MasterTemplate.AllowDragToGroup = false;
            this.radGridView1.MasterTemplate.AllowRowResize = false;
            this.radGridView1.MasterTemplate.AutoSizeColumnsMode = Telerik.WinControls.UI.GridViewAutoSizeColumnsMode.Fill;
            gridViewTextBoxColumn1.FieldName = "Id";
            gridViewTextBoxColumn1.HeaderText = "ID";
            gridViewTextBoxColumn1.IsVisible = false;
            gridViewTextBoxColumn1.Name = "IdCol";
            gridViewTextBoxColumn1.Width = 37;
            gridViewTextBoxColumn2.FieldName = "ParentId";
            gridViewTextBoxColumn2.HeaderText = "ParentID";
            gridViewTextBoxColumn2.IsVisible = false;
            gridViewTextBoxColumn2.Name = "ParentIdCol";
            gridViewTextBoxColumn2.Width = 48;
            gridViewTextBoxColumn3.FieldName = "VarName";
            gridViewTextBoxColumn3.HeaderText = "Name";
            gridViewTextBoxColumn3.Name = "NameCol";
            gridViewTextBoxColumn3.Width = 255;
            gridViewTextBoxColumn4.FieldName = "VarValue";
            gridViewTextBoxColumn4.HeaderText = "Value";
            gridViewTextBoxColumn4.Name = "ValueCol";
            gridViewTextBoxColumn4.Width = 78;
            gridViewTextBoxColumn5.FieldName = "VarUnits";
            gridViewTextBoxColumn5.HeaderText = "Units";
            gridViewTextBoxColumn5.Name = "UnitsCol";
            gridViewTextBoxColumn5.Width = 57;
            this.radGridView1.MasterTemplate.Columns.AddRange(new Telerik.WinControls.UI.GridViewDataColumn[] {
            gridViewTextBoxColumn1,
            gridViewTextBoxColumn2,
            gridViewTextBoxColumn3,
            gridViewTextBoxColumn4,
            gridViewTextBoxColumn5});
            this.radGridView1.MasterTemplate.EnableGrouping = false;
            this.radGridView1.MasterTemplate.EnableSorting = false;
            this.radGridView1.MasterTemplate.ShowRowHeaderColumn = false;
            this.radGridView1.Name = "radGridView1";
            this.radGridView1.Padding = new System.Windows.Forms.Padding(0, 0, 0, 1);
            //
            //
            //
            this.radGridView1.RootElement.Padding = new System.Windows.Forms.Padding(0, 0, 0, 1);
            this.radGridView1.ShowGroupPanel = false;
            this.radGridView1.ShowRowErrors = false;
            this.radGridView1.Size = new System.Drawing.Size(465, 465);
            this.radGridView1.TabIndex = 0;
            this.radGridView1.Text = "radGridView1";
            //
            // PropertiesControl
            //
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.Controls.Add(this.radGridView1);
            this.Name = "PropertiesControl";
            this.Size = new System.Drawing.Size(465, 465);
            ((System.ComponentModel.ISupportInitialize)(this.radGridView1)).EndInit();
            this.ResumeLayout(false);
 
        }
 
        #endregion
 
        private Telerik.WinControls.UI.RadGridView radGridView1;
    }
}

Thanks.
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Accepted
Richard Slade
Top achievements
Rank 2
answered on 25 Feb 2011, 01:31 AM
Hello,

The issue here is with the expand. In your code you are drilling down to try and expand for more levels than you actually have. In the case of the sample that you have given your expand code should be modified as follows:
private void ExpandRows()
{
    using (this.radGridView1.DeferRefresh())
    {
        foreach (var childRow in radGridView1.ChildRows)
        {
            childRow.IsExpanded = true;
            //foreach (var childChildRow in childRow.ChildRows)
            //{
            //    childChildRow.IsExpanded = true;
            //    foreach (var childChildChildRow in childChildRow.ChildRows)
            //    {
            //        //childChildChildRow.IsExpanded = true;
            //    }
            //}
        }
    }
}

However, even though you're not using it, the HasChildRows() method returns true even though the ChildRows.Count = 0.
I beleive Telerik need to look at this one to confirm that this [may be] is an issue. For the moment however, you should just drill down your expand for the number of levels that you expect in your hierarchy.

I hope that this is helpful but please let me know if I can help further
Richard
0
Richard Slade
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Rank 2
answered on 28 Feb 2011, 12:20 PM
Hello,

If you found this helpful, please remember to mark as answer. If you need further assistance, please let me know
Thanks
Richard
0
Emanuel Varga
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Rank 1
answered on 28 Feb 2011, 02:55 PM
Hello KARTHIK REDDY KAMIDI, Richard,

I've submitted a bug report with this issue this morning, it is related to the self referencing hierarchy and if you expand all the rows programatically it crashes if you are scrolling UP the grid, down everything is ok, i've tried everything to get around this but nothing works.

As soon as i have an answer from telerik i will get back to you (hopefully with a good workaround)

Hope this helps, if you have any other questions or comments, please let me know,

Best Regards,
Emanuel Varga
Telerik WinForms MVP
0
Richard Slade
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Rank 2
answered on 28 Feb 2011, 03:02 PM
Hi Emanuel,

Yes, I've been trying it too. Good that you have submitted a bug report.

I don't know if you have tried my sugestion, but that seems to work fine when expanding based on the sample that KARTHIK REDDY KAMIDI provided. However, the HasChildRows doesn't seem to be in sync with the true representation of whether the row has child rows.

Did you include the link to this forum post in your bug report? If not, it might be a good idea to do so, in order to keep a good track of all related material and incidents.

Let me know if you have any questions
Richard
0
Emanuel Varga
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Rank 1
answered on 28 Feb 2011, 03:06 PM
Hello again Richard,

I've submitted it this morning with no relation whatsoever to this post, I've been trying to come up with a working solution to this and 2 other very annoying problems with the self referencing hierarchy:
  1. You cannot set the datasource to null, it will crash (tried clearing relations and everything i could have tough of)
  2. Click the BestFit context menu option 2,3 times on the first cell header (the one with the hierarchy expand / collapse sign). Do you still see the expand collapse sign ?

Best Regards,
Emanuel Varga
Telerik WinForms MVP
0
Richard Slade
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Rank 2
answered on 28 Feb 2011, 03:31 PM
Hi Emanuel,

I don't want to clutter up this forum thread, so we can continue off-line if you prefer, but I've been doing some investigstion into your findings.
  • The BestFit issue also occurs if you double click the separator. The +- is still there, but you need to re-alter the column size manually in order to see it again.
  • Setting the data source to null is only a problem if you have AutoGenerateColumns = true. If you have this set to false and specifiy the columns, then it's fine.

Speak soon
regards,
Richard

0
Richard Slade
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Rank 2
answered on 28 Feb 2011, 03:51 PM
Hi Emanuel,

This will overcome the datasource issue when you have AutoGenerateColumns = true

Array columnsArray = this.radGridView1.Columns.ToArray();
foreach (GridViewColumn col in columnsArray)
{
    this.radGridView1.Columns.Remove(col.Name);
}
this.radGridView1.DataSource = null;

Let me know if you have any questions
Richard
0
Emanuel Varga
Top achievements
Rank 1
answered on 28 Feb 2011, 03:58 PM
Hello again Richard,

Why would you have to remove all the columns in order to set the datasource to null?
It's a bug on their side, honestly i would prefer not to have these kind of workarounds if by possible.

But please change that for to a reverse loop or use a foreach with a Columns.ToArray() to remove the columns.

I'll let you know as soon as i have an answer from telerik

Best Regards,
Emanuel Varga
Telerik WinForms MVP
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Richard Slade
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answered on 28 Feb 2011, 04:05 PM
Hi Emanuel,

I'm agreeing that it is a bug. I'm providing a workaround to this issue.

I believe that this is related to the child rows issue as per the Grid Scolling issue as the error that is received on this leads back to the GetChildRows method.

Let me know if you have further comments
Richard
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KARTHIK REDDY KAMIDI
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answered on 28 Feb 2011, 05:38 PM
Richard,

Thank you very much for the workaround. I was desperately looking for a solution.

Thanks.
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KARTHIK REDDY KAMIDI
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answered on 28 Feb 2011, 05:40 PM
Emanuel,

Thank you for looking into this issue and posting it as a bug. Hopefully Telerik will fix this as soon as possible.

Thanks.
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KARTHIK REDDY KAMIDI
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answered on 28 Feb 2011, 08:45 PM
Hello,

I've run into another problem with the grid. After the user changes a value, I have to reevaluate all cells in the second column and reload their values.

private void ReloadVariables()
{
    using (this.radGridView1.DeferRefresh())
    {
        foreach (var row in radGridView1.Rows)
        {
            var varmodel = row.Tag as Model;
            row.Cells[3].Value = varmodel.Value + " (Upd)";  // business logic goes here
        }
    }
}
 
 
void radGridView1_RowValidated(object sender, RowValidatedEventArgs e)
{
    ReloadVariables();
}
 
 
public PropertiesControl()
{
    InitializeComponent();
 
    stopwatch.Start();
 
    SetupRadGridviewRelation();
 
    radGridView1.RowValidated += new RowValidatedEventHandler(radGridView1_RowValidated);
}

The above code takes care of that. But the problem is that I have about 400 rows in the grid and after the ReloadVariables() method is called the grid scrolls to the top. That is the user is editing a cell somewhere in the 300th row and after editing and while trying to move to the next row, the grid automatically scrolls to the top.

If I do not user DeferRefresh() in the ReloadVariables(), the grid maintains its position, but I find that then the ReloadVariables() method is taking time.

Is there a workaround for this?

Thanks.
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Emanuel Varga
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answered on 01 Mar 2011, 10:01 AM
Hello again,

I have a different proposal for you, i know it's not the cleanest out there, but the row validated event will only fire after the user has changed the row, and it will fire every time the user changes a row, i would suggest you use the CellValueChanged event like so:
void radGridView1_CellValueChanged(object sender, GridViewCellEventArgs e)
        {
            if (e.ColumnIndex == 1)
            {
                var timer = new Timer();
                timer.Interval = 20;
                timer.Tick += delegate
                {
                    timer.Enabled = false;
                    ReloadVariables();
                };
 
                timer.Enabled = true;
            }
        }

or in order to remember the position on the grid you can just save the values of the scrollbars in the ReloadVariables, like so;
private void ReloadVariables()
{
    var scrollPos = radGridView1.GridElement.VScrollBar.Value;
    using (radGridView1.DeferRefresh())
    {
        foreach (var row in radGridView1.Rows)
        {
            var varmodel = row.Tag as Model;
            row.Cells[3].Value = varmodel.Value + " (Upd)"// business logic goes here
        }
    }
    radGridView1.GridElement.VScrollBar.Value = scrollPos;
}

Hope this helps, if you have any other questions or comments, please let me know,

Best Regards,
Emanuel Varga
Telerik WinForms MVP
0
Ivan Todorov
Telerik team
answered on 01 Mar 2011, 11:41 AM
Hi all,

@KARTHIK: Emanuel's suggestions sound reasonable and you should try them. I took a look at your sample and I am wondering why are you not using the grid in bound mode. Doing so will prevent you from bothering of updating items. Are you experiencing issues with the bound mode?

@Richard, Emanuel: Thank you guys for following up on this thread and reporting the issues encountered.

Regards,
Ivan Todorov
the Telerik team
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KARTHIK REDDY KAMIDI
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Richard Slade
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KARTHIK REDDY KAMIDI
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Emanuel Varga
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Ivan Todorov
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