How to get Value (Text) of dynamically created TextBox in ASP.Net using C# and VB.Net?

Question

how to change size of the panel dynamically vb.net

Answer 1

HTML Markup
The HTML Markup consists of an ASP.Net Panel control and two Buttons, one for adding TextBoxes and other one for getting the values of the dynamically generated TextBoxes.

<asp:Panel ID="pnlTextBoxes" runat="server">
</asp:Panel>
<hr />
<asp:Button ID="btnAdd" runat="server" Text="Add New" OnClick="AddTextBox" />
<asp:Button ID="btnGet" runat="server" Text="Get Values" OnClick="GetTextBoxValues" />

Dynamically creating and adding TextBoxes on Button Click
C#

protected void AddTextBox(object sender, EventArgs e)
{
    int index = pnlTextBoxes.Controls.OfType<TextBox>().ToList().Count + 1;
    this.CreateTextBox("txtDynamic" + index);
}

private void CreateTextBox(string id)
{
    TextBox txt = new TextBox();
    txt.ID = id;
    pnlTextBoxes.Controls.Add(txt);

    Literal lt = new Literal();
    lt.Text = "<br />";
    pnlTextBoxes.Controls.Add(lt);
}

VB.Net

Protected Sub AddTextBox(sender As Object, e As EventArgs)
    Dim index As Integer = pnlTextBoxes.Controls.OfType(Of TextBox)().ToList().Count + 1
    Me.CreateTextBox("txtDynamic" & index)
End Sub

Private Sub CreateTextBox(id As String)
    Dim txt As New TextBox()
    txt.ID = id
    pnlTextBoxes.Controls.Add(txt)

    Dim lt As New Literal()
    lt.Text = "<br />"
    pnlTextBoxes.Controls.Add(lt)
End Sub

Retaining the dynamic TextBoxes on PostBack

C#

protected void Page_PreInit(object sender, EventArgs e)
{
    List<string> keys = Request.Form.AllKeys.Where(key => key.Contains("txtDynamic")).ToList();
    int i = 1;
    foreach (string key in keys)
    {
        this.CreateTextBox("txtDynamic" + i);
        i++;
    }
}

VB.Net

Protected Sub Page_PreInit(sender As Object, e As EventArgs) Handles Me.PreInit
    Dim keys As List(Of String) = Request.Form.AllKeys.Where(Function(key) key.Contains("txtDynamic")).ToList()
    Dim i As Integer = 1
    For Each key As String In keys
        Me.CreateTextBox("txtDynamic" & i)
        i += 1
    Next
End Sub

Getting values of dynamically created TextBoxes

C#

protected void GetTextBoxValues(object sender, EventArgs e)
{
    string message = "";
    foreach (TextBox textBox in pnlTextBoxes.Controls.OfType<TextBox>())
    {
        message += textBox.ID + ": " + textBox.Text + "\\n";
    }
    ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('" + message + "');", true);
}

VB.Net

Protected Sub GetTextBoxValues(sender As Object, e As EventArgs)
    Dim message As String = ""
    For Each textBox As TextBox In pnlTextBoxes.Controls.OfType(Of TextBox)()
        message += textBox.ID + ": " + textBox.Text + "\n"
    Next
    ClientScript.RegisterClientScriptBlock(Me.GetType(), "alert", "alert('" & message & "');", True)
End Sub