In this article I will explain with an example, how to use RadioButtons with ASP.Net GridView control using C# and VB.Net.
 
 
Database
Here I am making use of Microsoft’s Northwind Database. You can download it from here.
Download and install Northwind Database
 
 
HTML Markup
The HTML Markup consists of:
GridView: – For displaying data.
Columns
GridView consist of one TemplateField column and three BoundField columns
TemplateField consists of an ItemTemplate with two controls i.e. RadioButton and HiddenField. 
<asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false" OnPageIndexChanging="OnPaging" AllowPaging="true">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:RadioButton ID="RadioButton1" runat="server" onclick="RadioCheck(this);" />
                <asp:HiddenField ID="hfCustomerId" runat="server" Value='<%#Eval("CustomerID")%>' />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField ItemStyle-Width="150px" DataField="CustomerID" HeaderText="CustomerID" />
        <asp:BoundField ItemStyle-Width="150px" DataField="City" HeaderText="City" />
        <asp:BoundField ItemStyle-Width="150px" DataField="PostalCode" HeaderText="PostalCode" />
    </Columns>
</asp:GridView>
 
 
Namespaces
You will need to import the following namespaces.
C#
using System.Data;
using System.Configuration;
using System.Data.SqlClient;
 
VB.Net
Imports System.Data
Imports System.Configuration
Imports System.Data.SqlClient
 
 
Populating GridView with records from the Database
Page Load
Inside the Page Load event handler, the GetSelectedRecord function and BindGrid function are called.
C#
protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.GetSelectedRecord();
        this.BindGrid();
    }
}
 
VB.Net
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Me.GetSelectedRecord()
        Me.BindGrid()
    End If
End Sub
 
 
BindGrid
Inside the BindGrid method, the GridView is populated with the records fetched Customers table of SQL Server database.
C#
private void BindGrid()
{
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(conString))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            string query = "SELECT CustomerID,City,PostalCode FROM Customers";
            cmd.CommandText = query;
            cmd.Connection = con;
            using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
            {
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    gvCustomers.DataSource = dt;
                    gvCustomers.DataBind();
                }
            }
        }
    }
}
 
VB.Net
Private Sub BindGrid()
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand()
            Dim query As String = "SELECT CustomerID,City,PostalCode FROM Customers"
            cmd.CommandText = query
            cmd.Connection = con
            Using sda As SqlDataAdapter = New SqlDataAdapter(cmd)
                Using dt As DataTable = New DataTable()
                    sda.Fill(dt)
                    gvCustomers.DataSource = dt
                    gvCustomers.DataBind()
                End Using
            End Using
        End Using
    End Using
End Sub
 
 
Maintaining state of the RadioButtons
GetSelectedRecord
Inside the GetSelectedRecord, a FOR loop is executed over the GridView rows and searches for a RadioButton in each row.
If the RadioButton is checked, it retrieves the ID of the corresponding HiddenField in the same row and stores it in the ViewState.
C#
private void GetSelectedRecord()
{
    for (int i = 0; i < gvCustomers.Rows.Count; i++)
    {
        RadioButton rb = (RadioButton)gvCustomers.Rows[i].Cells[0].FindControl("RadioButton1");
        if (rb != null)
        {
            if (rb.Checked)
            {
                HiddenField hf = (HiddenField)gvCustomers.Rows[i].Cells[0].FindControl("hfCustomerId");
                if (hf != null)
                {
                    ViewState["SelectedContact"] = hf.Value;
                }
 
                break;
            }
        }
    }
}
VB.Net
Private Sub GetSelectedRecord()
    For i As Integer = 0 To gvCustomers.Rows.Count - 1
        Dim rb As RadioButton = DirectCast(gvCustomers.Rows(i).Cells(0).FindControl("RadioButton1"), RadioButton)
        If rb IsNot Nothing Then
            If rb.Checked Then
                Dim hf As HiddenField = DirectCast(gvCustomers.Rows(i).Cells(0).FindControl("hfCustomerId"), HiddenField)
                If hf IsNot Nothing Then
                    ViewState("SelectedContact") = hf.Value
                End If
                Exit For
            End If
        End If
    Next
End Sub
 
SetSelectedRecord
Inside this method, a FOR loop is executed over the GridView rows and searches for a RadioButton and a HiddenField in each row.
If the value of the HiddenField and value of the ViewState is same then, the corresponding RadioButton checked property set to true.
C#
private void SetSelectedRecord()
{
    for (int i = 0; i < gvCustomers.Rows.Count; i++)
    {
        RadioButton rb = (RadioButton)gvCustomers.Rows[i].Cells[0].FindControl("RadioButton1");
        if (rb != null)
        {
            HiddenField hf = (HiddenField)gvCustomers.Rows[i].Cells[0].FindControl("hfCustomerId");
            if (hf != null && ViewState["SelectedContact"] != null)
            {
                if (hf.Value.Equals(ViewState["SelectedContact"].ToString()))
                {
                    rb.Checked = true;
                    break;
                }
            }
        }
    }
}
 
VB.Net
Private Sub SetSelectedRecord()
    For i As Integer = 0 To gvCustomers.Rows.Count - 1
        Dim rb As RadioButton = DirectCast(gvCustomers.Rows(i).Cells(0).FindControl("RadioButton1"), RadioButton)
        If rb IsNot Nothing Then
            Dim hf As HiddenField = DirectCast(gvCustomers.Rows(i).Cells(0).FindControl("hfCustomerId"), HiddenField)
            If hf IsNot Nothing And ViewState("SelectedContact") IsNot Nothing Then
                If hf.Value.Equals(ViewState("SelectedContact").ToString()) Then
                    rb.Checked = True
                    Exit For
                End If
            End If
        End If
    Next
End Sub
 
 
Paging
Inside the OnPageIndexChanging event handler, the PageIndex property of the GridView is updated with the new Page Number which was clicked.
The GridView is populated using the BindGrid method which in-turn displays the new GridView page. 
Finally, the SetSelectedRecord method is called.
C#
protected void OnPaging(object sender, GridViewPageEventArgs e)
{
    gvCustomers.PageIndex = e.NewPageIndex;
    this.BindGrid();
    this.SetSelectedRecord();
}
VB.Net
Protected Sub OnPaging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
    gvCustomers.PageIndex = e.NewPageIndex
    Me.BindGrid()
    Me.SetSelectedRecord()
End Sub
 
 
Client Side JavaScript
If RadioButton is marked checked, the following JavaScript function is called.
A FOR loop is executed over the RadioButtons and ensures that only one RadioButton is checked at a time. If other RadioButton is checked, it unchecks those RadioButton inside the GridView.
<script type="text/javascript">
    function RadioCheck(rb) {
        var gv = document.getElementById("<%=gvCustomers.ClientID%>");
        var rbs = gv.getElementsByTagName("input");
        for (var i = 0; i < rbs.length; i++) {
            if (rbs[i].type == "radio") {
                if (rbs[i].checked && rbs[i] != rb) {
                    rbs[i].checked = false;
                    break;
                }
            }
        }
    }
</script>
 
 
Screenshot
Using RadioButtons with ASP.Net GridView Control
 
 
Downloads
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