[Solved] Button Click event is not firing in ASP.Net GridView

Hi ameera,

You are giving wrong viewstate name please check below code it's working.

HTML

<asp:GridView ID="Gridview1" runat="server" ShowFooter="true" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="RowNumber" HeaderText="Row Number" />
        <asp:TemplateField HeaderText="Header 1">
            <ItemTemplate>
                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Header 2">
            <ItemTemplate>
                <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Header 3">
            <ItemTemplate>
                <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            </ItemTemplate>
            <FooterStyle HorizontalAlign="Right" />
            <FooterTemplate>
                <asp:Button ID="ButtonAdd" runat="server" Text="Add New Row" class="btn btn-success"
                    OnClick="ButtonAdd_Click" />
            </FooterTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Namespaces

C#

using System.Data;

VB.Net

Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        SetInitialRow();
    }
}

private void SetInitialRow()
{
    DataTable dt = new DataTable();
    DataRow dr = null;
    dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
    dt.Columns.Add(new DataColumn("Column1", typeof(string)));
    dt.Columns.Add(new DataColumn("Column2", typeof(string)));
    dt.Columns.Add(new DataColumn("Column3", typeof(string)));
    dr = dt.NewRow();
    dr["RowNumber"] = 1;
    dr["Column1"] = string.Empty;
    dr["Column2"] = string.Empty;
    dr["Column3"] = string.Empty;
    dt.Rows.Add(dr);
    ViewState["CurrentTable"] = dt;
    Gridview1.DataSource = dt;
    Gridview1.DataBind();
}

private void AddNewRowToGrid()
{
    int rowIndex = 0;
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
        DataRow drCurrentRow = null;
        if (dtCurrentTable.Rows.Count > 0)
        {
            for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
            {
                //extract the TextBox values
                TextBox box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
                TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
                TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
                drCurrentRow = dtCurrentTable.NewRow();
                drCurrentRow["RowNumber"] = i + 1;
                dtCurrentTable.Rows[i - 1]["Column1"] = box1.Text;
                dtCurrentTable.Rows[i - 1]["Column2"] = box2.Text;
                dtCurrentTable.Rows[i - 1]["Column3"] = box3.Text;
                rowIndex++;
            }
            dtCurrentTable.Rows.Add(drCurrentRow);
            ViewState["CurrentTable"] = dtCurrentTable;
            Gridview1.DataSource = dtCurrentTable;
            Gridview1.DataBind();
        }
    }

    else
    {
        Response.Write("ViewState is null");
    }
    //Set Previous Data on Postbacks
    SetPreviousData();
}

private void SetPreviousData()
{
    int rowIndex = 0;
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dt = (DataTable)ViewState["CurrentTable"];
        if (dt.Rows.Count > 0)
        {
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                TextBox box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
                TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
                TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
                box1.Text = dt.Rows[i]["Column1"].ToString();
                box2.Text = dt.Rows[i]["Column2"].ToString();
                box3.Text = dt.Rows[i]["Column3"].ToString();
                rowIndex++;
            }
        }
    }
}

protected void ButtonAdd_Click(object sender, EventArgs e)
{
    AddNewRowToGrid();
}

VB.Net

Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        SetInitialRow()
    End If
End Sub

Private Sub SetInitialRow()
    Dim dt As New DataTable()
    Dim dr As DataRow = Nothing
    Dim rowNumber As DataColumn = New DataColumn("rowNumber")
    rowNumber.DataType = System.Type.GetType("System.String")
    dt.Columns.Add(rowNumber)
    Dim column1 As DataColumn = New DataColumn("column1")
    column1.DataType = System.Type.GetType("System.String")
    dt.Columns.Add(column1)
    Dim column2 As DataColumn = New DataColumn("column2")
    column2.DataType = System.Type.GetType("System.String")
    dt.Columns.Add(column2)
    Dim column3 As DataColumn = New DataColumn("column3")
    column3.DataType = System.Type.GetType("System.String")
    dt.Columns.Add(column3)
    dr = dt.NewRow()
    dr("rowNumber") = 1
    dr("column1") = String.Empty
    dr("column2") = String.Empty
    dr("column3") = String.Empty
    dt.Rows.Add(dr)
    ViewState("currentTable") = dt
    Gridview1.DataSource = dt
    Gridview1.DataBind()
End Sub
Private Sub AddNewRowToGrid()
    Dim rowIndex As Integer = 0
    'if (ViewState["CurrentTable"] != null)
    If ViewState("currentTable") IsNot Nothing Then
        Dim dtCurrentTable As New DataTable
        dtCurrentTable = TryCast(ViewState("currentTable"), DataTable)

        Dim drCurrentRow As DataRow
        drCurrentRow = Nothing
        If dtCurrentTable.Rows.Count > 0 Then
            For i As Integer = 1 To dtCurrentTable.Rows.Count
                ' extract the TextBox values
                Dim box1 As TextBox = TryCast(Gridview1.Rows(rowIndex).Cells(1).FindControl("textbox1"), TextBox)
                Dim box2 As TextBox = TryCast(Gridview1.Rows(rowIndex).Cells(2).FindControl("textbox2"), TextBox)
                Dim box3 As TextBox = TryCast(Gridview1.Rows(rowIndex).Cells(3).FindControl("textbox3"), TextBox)
                drCurrentRow = dtCurrentTable.NewRow()
                drCurrentRow("rowNumber") = i + 1
                dtCurrentTable.Rows(i - 1)("column1") = box1.Text
                dtCurrentTable.Rows(i - 1)("column2") = box2.Text
                dtCurrentTable.Rows(i - 1)("column3") = box3.Text
            Next
            dtCurrentTable.Rows.Add(drCurrentRow)
            ViewState("currentTable") = dtCurrentTable
            Gridview1.DataSource = dtCurrentTable
            Gridview1.DataBind()
        Else
            Response.Write("ViewState is null")
        End If
        'Set Previous Data on Postbacks
        SetPreviousData()
    End If
End Sub
Private Sub SetPreviousData()

    Dim rowIndex As Integer = 0
    If ViewState("currentTable") IsNot Nothing Then
        Dim dt As New DataTable()
        dt = TryCast(ViewState("currentTable"), DataTable)
        If dt.Rows.Count > 0 Then
            For i As Integer = 0 To dt.Rows.Count - 1
                Dim box1 As TextBox = TryCast(Gridview1.Rows(rowIndex).Cells(1).FindControl("textbox1"), TextBox)
                Dim box2 As TextBox = TryCast(Gridview1.Rows(rowIndex).Cells(2).FindControl("textbox2"), TextBox)
                Dim box3 As TextBox = TryCast(Gridview1.Rows(rowIndex).Cells(3).FindControl("textbox3"), TextBox)
                box1.Text = dt.Rows(i)("column1").ToString()
                box2.Text = dt.Rows(i)("column2").ToString()
                box3.Text = dt.Rows(i)("column3").ToString()
            Next

        End If

    End If
End Sub
Protected Sub ButtonAdd_Click(sender As Object, e As System.EventArgs)
    AddNewRowToGrid()
End Sub

Screenshot