Get datakeyvalue of multiple selected rows using checkbox at client side

[Priyanka]

I have RadGrid on web page with ckeckbox inside it.

I want to fetch "datakey value" of multiple selected rows using checkbox at client side on button(which is outside RadGrid) click.

I tried below code but its not working:

<telerik:RadGrid ID="RadGrid1" EnableViewState="false" runat="server" AllowPaging="true" OnItemDataBound="RadGrid1_ItemDataBound"

                        AllowSorting="False" AllowFilteringByColumn="true" GridLines="None" OnInit="RadGrid1_Init" OnDeleteCommand="RadGrid1_DeleteCommand" >

                        <ItemStyle Wrap="false"></ItemStyle>

                        <MasterTableView AllowMultiColumnSorting="true" TableLayout="Fixed" DataKeyNames="Id" ClientDataKeyNames="Id">

                            <Columns>     

                                <telerik:GridTemplateColumn UniqueName="SelectRow" HeaderText="Select" AllowFiltering="false" HeaderStyle-Width="20px">

                                    <ItemTemplate>

<telerik:RadScriptBlock ID="RadScriptBlock1" runat="server">

<script type="text/javascript">

    function getDataKeyValues(chk) {

            

        //find datakeyvalue of selected row

        var masterTable = $find("<%=RadGrid1.ClientID%>").get_masterTableView();

        var count = masterTable.get_dataItems().length;

        var checkbox;

        var item;

        for (var i = 0; i < count; i++) {

            item = masterTable.get_dataItems()[i];

            checkbox = item.findElement("CheckBox1");

            if (checkbox.checked) {

                var dataKeyValue = item.getDataKeyValue("Id");

                //alert(dataKeyValue);

               


                var hiddenValue = document.getElementById("hdn_Id"); //get Id inside Hidden field

                hiddenValue.value = dataKeyValue;

                alert(hiddenValue.value);

            }

        }

    }

</script>

</telerik:RadScriptBlock>

                                        <asp:CheckBox ID="CheckBox1" runat="server" />

                                    </ItemTemplate>

                                </telerik:GridTemplateColumn>

                                <telerik:GridNumericColumn UniqueName="Id" DataField="Id" HeaderText="Id" HeaderStyle-Width="20px" AllowFiltering="False">

                                </telerik:GridNumericColumn>

                                <telerik:GridBoundColumn DataField="Description" HeaderText="Description" AndCurrentFilterFunction="Contains" FilterListOptions="AllowAllFilters" HeaderStyle-Width="100px">

                                </telerik:GridBoundColumn>

                               


                            </Columns>

                        </MasterTableView>

                        <PagerStyle AlwaysVisible="true" Mode="NumericPages"></PagerStyle>

                        <ClientSettings>

                            <Selecting  AllowRowSelect="true" />

                            <ClientEvents OnCommand="RadGrid1_Command" OnRowDataBound="RadGrid1_RowDataBound"></ClientEvents>

                        </ClientSettings>

                    </telerik:RadGrid>

<br />

                    <asp:HiddenField ID="hdn_Id" runat="server" />

                    <asp:Button ID="btnPrint" runat="server" Text="Print" CssClass="btn btn-primary" OnClick="btnPrint_Click" />

protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)
        {
            if(e.Item is GridDataItem)
            {
                GridDataItem item = (GridDataItem)e.Item;
                CheckBox chk = (CheckBox)item.FindControl("CheckBox1");
                chk.Attributes.Add("onclick", "getDataKeyValues(this);");
            }
        }

protected void btnPrint_Click(object sender, EventArgs e)
        {
            funTax();
            foreach(GridDataItem item in RadGrid1.MasterTableView.Items)
            {
                CheckBox check = (CheckBox)item.FindControl("CheckBox1");
                if (check.Checked == true)
                {
                    string itemId = hdn_Id.Value;
                    //Response.Redirect("~/Test.aspx?Id=" + itemId);
                }
            }
        }

[Priyanka]

In above Javscript code I can successfully retrieve datakeyvalue of all the selected rows inside Hiddenfield.
But when I am trying to fetch the hidden field value in code behind on button click, it only shows datakeyvalue for last selected row of Grid not all selected.

Example: If I had selected checkbox with Id: 1, 3, 6 then in Javscript code, I am getting all the three selected rows datakeyvalue inside Hiddenfield.
But when I am trying to fetch the same hidden field values on button click, I get only last selected value i.e., 6

Please reply what is wrong ? I also need to pass the multiple selected datakeyvalue on other page

[Priyanka]

Modified javascript as below, and its working fine now.

<telerik:RadScriptBlock ID="RadScriptBlock1" runat="server">
<script type="text/javascript">
    function getDataKeyValues(chk) {

        //find datakeyvalue of selected row
        var masterTable = $find("<%=RadGrid1.ClientID%>").get_masterTableView();
        var count = masterTable.get_dataItems();
        var checkbox;
        var item;
        var res = "";
        for (var i = 0; i < count.length; i++) {
            item = masterTable.get_dataItems()[i];
            checkbox = item.findElement("CheckBox1");
            if (checkbox.checked) {
                var dataKeyValue = item.getDataKeyValue("Id");
                res += dataKeyValue+",";
                //window.location = "PrintInvoice.aspx?id=" + dataKeyValue;
            }
        }
        var hiddenValue = document.getElementById("hdn_Id"); //get selected row's Id's inside Hidden field
        hiddenValue.value = res;
    }
</script>
</telerik:RadScriptBlock>

Thank you