Limit rows that can be inserted into ASP.Net GridView

Hi kankon,

Please refer below sample.

HTML

<form id="form1" runat="server">
    <div>
        <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"
                            OnClick="ButtonAdd_Click" />
                    </FooterTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
    </div>
</form>

Code

C#

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);

    //Store the DataTable in ViewState
    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 < 5)
        {
            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
        {
            ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('Maximum 5 Rows Allow');", true);
        }
    }
    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 Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        SetInitialRow();
    }
}
protected void ButtonAdd_Click(object sender, EventArgs e)
{
    AddNewRowToGrid();
}

Screenshot