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Why does the grid vanish on a postback from a embedded control?
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Hello,

I have this project, It has a WebHierarchicalDataGrid with an embedded DropdownBoxList. I placed the XMLDataSource object in the CS file. On selecting the dropdownlist inside the grid, i get a postback to the server however, the data in the grid will vanish unless I call the database server for data and rebind, and the dropdownlist change event will not fire. Only when I retrieve the data on each postback and rebind it, will the grid load and the dropdown event fire. I do not want to rebind the data in the grid, i just want to select an item from the dropdown list and have it call the server and get a list of data. How do i fix this?

 

/********************** ASPX ***********************/

<ig:WebHierarchicalDataGrid ID="WebHierarchicalDataGrid1" runat="server"
                Height="650px" Width="1900px" Key="LIST" DataKeyFields="UserId"
                AutoGenerateBands="false" AutoGenerateColumns="false">
                    <Columns>
                        <ig:BoundDataField DataFieldName="UserId" Key="UserId" Header-Text="CategoryID" Width="200px"><Header Text="CategoryID"></Header></ig:BoundDataField>
                        <ig:BoundDataField DataFieldName="Names" Key="Names" Header-Text="Names" Width="200px"><Header Text="Names"></Header></ig:BoundDataField>
                        <ig:BoundDataField DataFieldName="Location" Key="Location" Header-Text="Location" Width="200px"><Header Text="Location"></Header></ig:BoundDataField>
                        <ig:TemplateDataField Key="Image" Width="525px">
                            <ItemTemplate>
                                <asp:DropDownList ID="QType" runat="server" AutoPostBack="true" OnSelectedIndexChanged="SelectionChanged">
                                    <asp:ListItem Text="True/False" Value="1"></asp:ListItem>
                                    <asp:ListItem Text="Multiple Choice" Value="2"></asp:ListItem>
                                    <asp:ListItem Text="Multiple Answer" Value="3"></asp:ListItem>
                                </asp:DropDownList>
                            </ItemTemplate>
                            <Header Text="Image" />
                        </ig:TemplateDataField>
                        <ig:TemplateDataField Key="Chart" Width="300">
                            <ItemTemplate>
                                <igchart:UltraChart ID="UltraChart1" runat="server" EmptyChartText="Data Not Available." Version="11.2" DataSourceID="ods1" Height="50px" Width="50px">
                                </igchart:UltraChart>
                            </ItemTemplate>
                        </ig:TemplateDataField>
                    </Columns>
                   <Bands>
                   <ig:Band AutoGenerateColumns="false" DataMember="CASE" DataKeyFields="CaseId" ShowFooter="False">
                       <Columns>
                            <ig:BoundDataField DataFieldName="CaseId" Key="CaseId" Header-Text="CaseId" Width="200px"><Header Text="CaseId"></Header></ig:BoundDataField>
                            <ig:BoundDataField DataFieldName="Subject" Key="Subject" Header-Text="Subject" Width="200px"><Header Text="Subject"></Header></ig:BoundDataField>
                            <ig:BoundDataField DataFieldName="CreatedDate" Key="CreatedDate" Header-Text="CreatedDate" Width="200px"><Header Text="CreatedDate"></Header></ig:BoundDataField>
                       </Columns>
                   </ig:Band>
                   </Bands>

                </ig:WebHierarchicalDataGrid>

 

/*************************CS**********************/

        protected void Page_Load(object sender, EventArgs e)
        {
            try
            {
                StartDt = WebDatePicker1.Text;

                if (!Page.IsPostBack)
                {
                    using (XmlDataSource xmlDataSource = new XmlDataSource())
                    {
                        xmlDataSource.XPath = @"/LIST/USER";
                        xmlDataSource.EnableCaching = false;
                        xmlDataSource.Data = GetCases(StartDt);
                        WebHierarchicalDataGrid1.GridView.ClearDataSource();
                        WebHierarchicalDataGrid1.DataSource = xmlDataSource;
                        WebHierarchicalDataGrid1.DataBind();
                    }
                }
            }
            catch (Exception exc)
            {

            }
        }
        protected void SelectionChanged(object sender, EventArgs e)
        {
            DropDownList d = (DropDownList)sender;
        }
        private string GetCases(string date)
        {
            DataRow dataRow;
            DataTable dataTable = new DataTable();
            string strSQL = "dbo.getCases";
            string result = "";
            try
            {
                using (SqlConnection connection = new SqlConnection(ConnDb))
                {
                    using (SqlCommand command = new SqlCommand(strSQL, connection))
                    {
                        command.CommandType = CommandType.StoredProcedure;
                        command.Parameters.AddWithValue("@CreatedDate", date);
                        using (SqlDataAdapter dataAdapter = new SqlDataAdapter(command))
                        {
                            dataAdapter.Fill(dataTable);
                        }

                        if (dataTable.Rows.Count > 0)
                        {
                            dataRow = dataTable.Rows[0];
                            result = dataRow[0].ToString();
                        }
                    }
                }
            }
            catch (Exception e)
            {
            }
            return result;
        }

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