Why RadGrid never delete child row after user deleting parent row?

[Stanley]

Please refer the video below
http://www.youtube.com/watch?v=YwCubFXo8bg 
From the video, you can see 5 child row record.
After deleting a child row, child row count = 4.
After deleting a parent row, child row count still is 4.

For the source code, please get it from url below
File name is  DeleteParentRow.zip 
http://sdrv.ms/PU4ZgZ

Auto delete child row function, any way can be done?
Thanks.
  

[Julian Benkov]

Hi Stanley,

Thank you for writing.

You can use the UserDeletingRow to implement this functionality. Here is the changed example:

using System;
using System.Data;
using System.Windows.Forms;
using Telerik.WinControls.UI;

namespace ChildGridLoadOnDemand
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            radGridView1.UserDeletingRow += new GridViewRowCancelEventHandler(radGridView1_UserDeletingRow);
        }

        void radGridView1_UserDeletingRow(object sender, GridViewRowCancelEventArgs e)
        {
            GridViewTemplate childTemplate = radGridView1.Templates[0];

            using (childTemplate.DeferRefresh())
            {
                for (int i = 0; i < e.Rows.Length; i++)
                {
                    int index = 0;
                    while (index < childTemplate.Rows.Count)
                    {
                        if (((int)childTemplate.Rows[index].Cells["ID"].Value).CompareTo((int)e.Rows[i].Cells["ID"].Value) == 0)
                        {
                            childTemplate.Rows.RemoveAt(index);
                        }
                        else
                        {
                            index++;
                        }
                    }
                }
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            populateGridHeader();
        }

        private void populateGridHeader()
        {
            CreateMasterTemplate();

            GridViewTemplate childTemplate = CreateChildTemplate();
            childTemplate.DataSource = GetDetTable();

            GridViewRelation relation = new GridViewRelation(this.radGridView1.MasterTemplate, childTemplate);
            relation.RelationName = "childTemplate";
            relation.ParentColumnNames.Add("ID");
            relation.ChildColumnNames.Add("ID");

            this.radGridView1.Relations.Add(relation);

            this.radGridView1.RowSourceNeeded += new GridViewRowSourceNeededEventHandler(radGridView1_RowSourceNeeded);
        }

        private void radGridView1_RowSourceNeeded(object sender, GridViewRowSourceNeededEventArgs e)
        {
            MessageBox.Show("Yes");
        }

        private void CreateMasterTemplate()
        {

            //ID
            GridViewTextBoxColumn ColID = new GridViewTextBoxColumn();
            ColID.FieldName = "ID";
            ColID.HeaderText = "ID";
            ColID.Name = "ID";
            ColID.Width = 100;
            radGridView1.MasterTemplate.Columns.Add(ColID);

            //Brand
            GridViewTextBoxColumn ColBrand = new GridViewTextBoxColumn();
            ColBrand.FieldName = "Brand";
            ColBrand.HeaderText = "Brand";
            ColBrand.Name = "Brand";
            ColBrand.Width = 100;
            radGridView1.MasterTemplate.Columns.Add(ColBrand);

            radGridView1.DataSource = GetHdrTable();
        }

        private GridViewTemplate CreateChildTemplate()
        {
            GridViewTemplate childTemplate = new GridViewTemplate();
            this.radGridView1.Templates.Add(childTemplate);

            //ID
            GridViewTextBoxColumn ColID = new GridViewTextBoxColumn();
            ColID.FieldName = "ID";
            ColID.HeaderText = "ID";
            ColID.Name = "ID";
            ColID.Width = 100;
            childTemplate.Columns.Add(ColID);

            //Model
            GridViewTextBoxColumn ColumnModel = new GridViewTextBoxColumn();
            ColumnModel.FieldName = "Model";
            ColumnModel.HeaderText = "Model";
            ColumnModel.Name = "Model";
            ColumnModel.Width = 100;
            childTemplate.Columns.Add(ColumnModel);

            childTemplate.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
            childTemplate.HierarchyDataProvider = new GridViewEventDataProvider(childTemplate);

            return childTemplate;
        }

        static DataTable GetHdrTable()
        {
            //
            // Here we create a DataTable with four columns.
            //
            DataTable table = new DataTable();
            table.Columns.Add("ID", typeof(int));
            table.Columns.Add("Brand", typeof(string));
            //
            // Here we add five DataRows.
            //
            table.Rows.Add(1, "Apple");
            table.Rows.Add(2, "Samsung");

            return table;
        }

        static DataTable GetDetTable()
        {
            //
            // Here we create a DataTable with four columns.
            //
            DataTable table = new DataTable();
            table.Columns.Add("ID", typeof(int));
            table.Columns.Add("Model", typeof(string));
            //
            // Here we add five DataRows.
            //
            table.Rows.Add(1, "Ipad");
            table.Rows.Add(1, "Iphone");
            table.Rows.Add(1, "Macbook");
            table.Rows.Add(2, "Galaxy Tab");
            table.Rows.Add(2, "Galaxy S3");

            return table;
        }

        private void radGridView1_UserDeletedRow(object sender, GridViewRowEventArgs e)
        {
            MessageBox.Show(((DataTable)radGridView1.Templates[0].DataSource).Rows.Count.ToString());
        }
    }
}

I hope this helps.

Kind regards,
Julian Benkov
the Telerik team