Prevent insert empty data from dynamic ASP.Net GridView row using C# and VB.Net

Hi lingers,

Refer the updated code.

HTML

<asp:TextBox ID="txtNo" runat="server" />
<asp:Button ID="Button1" Text="Add" OnClick="Add" runat="server" />
<hr />
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" Width="315px">
    <Columns>
        <asp:TemplateField HeaderText="First Name">
            <ItemTemplate>
                <asp:TextBox ID="txtFirstName" runat="server" Text='<%# Eval("FirstName") %>' />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Last Name">
            <ItemTemplate>
                <asp:TextBox ID="txtLastName" runat="server" Text='<%# Eval("LastName") %>' />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Age">
            <ItemTemplate>
                <asp:DropDownList ID="ageperson" runat="server" Height="25px"
                    Style="margin-left: 0px" Width="416px"
                    AutoPostBack="True" Font-Names="Century Gothic" Font-Bold="True">
                    <asp:ListItem Selected="True" Value="1">Offline Die</asp:ListItem>
                    <asp:ListItem Value="3">Cylinder</asp:ListItem>
                    <asp:ListItem Value="4">Cutting Die</asp:ListItem>
                    <asp:ListItem Value="6">Embossing</asp:ListItem>
                </asp:DropDownList>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<asp:Button Text="Save" runat="server" OnClick="OnSave" />

Namespaces

C#

using System.Configuration;
using System.Data;
using System.Data.SqlClient;

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (this.GridView1.Rows.Count > 0 && Session["myDatatable"] != null)
    {
        DataTable dt = (DataTable)Session["myDatatable"];
        dt.Clear();
        foreach (GridViewRow row in this.GridView1.Rows)
        {
            string firstName = (row.FindControl("txtFirstName") as TextBox).Text;
            string lastName = (row.FindControl("txtLastName") as TextBox).Text;
            string age = (row.FindControl("ageperson") as DropDownList).SelectedItem.Text;
            dt.Rows.Add(firstName, lastName, age);
            (row.FindControl("ageperson") as DropDownList).Items.FindByText(age).Selected = true;
        }
        Session["myDatatable"] = dt;
    }
}

public void AddNewData()
{
    DataTable dt = new DataTable();
    if (Session["myDatatable"] != null)
    {
        dt = (DataTable)Session["myDatatable"];
    }
    else
    {
        dt.Columns.Add("FirstName");
        dt.Columns.Add("LastName");
        dt.Columns.Add("age");
    }

    DataRow drow = dt.NewRow();
    drow["FirstName"] = "";
    drow["LastName"] = "";
    drow["age"] = "";
    dt.Rows.Add(drow);
    Session["myDatatable"] = dt;
}

public void BindGridview()
{
    if (Session["myDatatable"] != null)
    {
        DataTable dt = (DataTable)Session["myDatatable"];

        if ((dt != null) && (dt.Rows.Count > 0))
        {
            GridView1.Visible = true;
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }
        else
        {
            GridView1.Visible = false;
        }
    }
}

protected void Add(object sender, EventArgs e)
{
    for (int i = 0; i < Convert.ToInt32(txtNo.Text); i++)
    {
        AddNewData();
    }
    BindGridview();
}

protected void OnSave(object sender, EventArgs e)
{
    foreach (GridViewRow row in GridView1.Rows)
    {
        string firstName = (row.FindControl("txtFirstName") as TextBox).Text;
        string lastName = (row.FindControl("txtLastName") as TextBox).Text;
        string age = (row.FindControl("ageperson") as DropDownList).SelectedItem.Text;
        if (!string.IsNullOrEmpty(firstName) && !string.IsNullOrEmpty(lastName))
        {
            string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
            string query = "INSERT INTO Student VALUES(@First,@Last,@age)";
            using (SqlConnection con = new SqlConnection(conString))
            {
                using (SqlCommand cmd = new SqlCommand(query))
                {
                    cmd.Connection = con;
                    cmd.Parameters.AddWithValue("@First", firstName);
                    cmd.Parameters.AddWithValue("@Last", lastName);
                    cmd.Parameters.AddWithValue("@age", age);
                    con.Open();

                    cmd.ExecuteNonQuery();
                }
                con.Close();
            }
        }
    }

    Session["myDatatable"] = null;
    Response.Redirect("material.aspx");
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Me.GridView1.Rows.Count > 0 AndAlso Session("myDatatable") IsNot Nothing Then
        Dim dt As DataTable = CType(Session("myDatatable"), DataTable)
        dt.Clear()
        For Each row As GridViewRow In Me.GridView1.Rows
            Dim firstName As String = (TryCast(row.FindControl("txtFirstName"), TextBox)).Text
            Dim lastName As String = (TryCast(row.FindControl("txtLastName"), TextBox)).Text
            Dim age As String = (TryCast(row.FindControl("ageperson"), DropDownList)).SelectedItem.Text
            dt.Rows.Add(firstName, lastName, age)
            TryCast(row.FindControl("ageperson"), DropDownList).Items.FindByText(age).Selected = True
        Next

        Session("myDatatable") = dt
    End If
End Sub

Public Sub AddNewData()
    Dim dt As DataTable = New DataTable()
    If Session("myDatatable") IsNot Nothing Then
        dt = CType(Session("myDatatable"), DataTable)
    Else
        dt.Columns.Add("FirstName")
        dt.Columns.Add("LastName")
        dt.Columns.Add("age")
    End If
    Dim drow As DataRow = dt.NewRow()
    drow("FirstName") = ""
    drow("LastName") = ""
    drow("age") = ""
    dt.Rows.Add(drow)
    Session("myDatatable") = dt
End Sub

Public Sub BindGridview()
    If Session("myDatatable") IsNot Nothing Then
        Dim dt As DataTable = CType(Session("myDatatable"), DataTable)
        If (dt IsNot Nothing) AndAlso (dt.Rows.Count > 0) Then
            GridView1.Visible = True
            GridView1.DataSource = dt
            GridView1.DataBind()
        Else
            GridView1.Visible = False
        End If
    End If
End Sub

Protected Sub Add(ByVal sender As Object, ByVal e As EventArgs)
    For i As Integer = 0 To Convert.ToInt32(txtNo.Text) - 1
        AddNewData()
    Next

    BindGridview()
End Sub

Protected Sub OnSave(ByVal sender As Object, ByVal e As EventArgs)
    For Each row As GridViewRow In GridView1.Rows
        Dim firstName As String = TryCast(row.FindControl("txtFirstName"), TextBox).Text
        Dim lastName As String = TryCast(row.FindControl("txtLastName"), TextBox).Text
        Dim age As String = TryCast(row.FindControl("ageperson"), DropDownList).SelectedItem.Text
        If Not String.IsNullOrEmpty(firstName) AndAlso Not String.IsNullOrEmpty(lastName) Then
            Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
            Dim query As String = "INSERT INTO Student VALUES(@First,@Last,@age)"
            Using con As SqlConnection = New SqlConnection(conString)
                Using cmd As SqlCommand = New SqlCommand(query)
                    cmd.Connection = con
                    cmd.Parameters.AddWithValue("@First", firstName)
                    cmd.Parameters.AddWithValue("@Last", lastName)
                    cmd.Parameters.AddWithValue("@age", age)
                    con.Open()
                    cmd.ExecuteNonQuery()
                    con.Close()
                End Using
            End Using
        End If
    Next

    Session("myDatatable") = Nothing
    Response.Redirect("material.aspx")
End Sub