Dynamically add a new text box on button click

Question

I have textbox \"tb1\" on my page and I want users to be able to add another if they need to input more data. I have the following code:

VB:

Answer 1

You could build your own TextBoxCollection CompositeControl which would enable you to achieve the functionality you require.

I have put together a basic example of how it could be achieved.

Control

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace ASPNetWebApplication.Controls
{
    public class TextBoxCollection : CompositeControl
    {
        private List TextBoxes
        {
            get
            {
                if (ViewState["TextBoxes"] == null)
                {
                    ViewState["TextBoxes"] = new List();
                }

                return (List)ViewState["TextBoxes"];
            }
            set
            {
                ViewState["TextBoxes"] = value;
            }
        }

        protected override void CreateChildControls()
        {
            foreach (string textBox in TextBoxes)
            {
                Controls.Add(new TextBox() { ID = textBox });
                Controls.Add(new Literal() { Text = "
" });
            }
        }

        public TextBox GetTextBox(string id)
        {
            return (TextBox)Controls.Cast().Where(t => (t.ID == null ? "" : t.ID.ToLower()) == id.ToLower()).SingleOrDefault();
        }

        public void AddTextBox(string id)
        {
            TextBoxes.Add(id);
        }
    }
}

Example Markup

Note: Change Assembly="ASPNetWebApplication" to the name of your assembly.

<%@ Register Assembly="ASPNetWebApplication" Namespace="ASPNetWebApplication.Controls" TagPrefix="ASPNetWebApplication" %>

...

Example Codebehind

protected void AddTextBoxesButton_Click(object sender, EventArgs e)
{
    for (int i = 0; i < 10; i++)
    {
        TextBoxCollection1.AddTextBox(string.Format("TextBox{0}", i));
    }

    AddTextBoxesButton.Visible = false;
    GetTextBoxValuesButton.Visible = true;
}

protected void GetTextBoxValuesButton_Click(object sender, EventArgs e)
{
    TextBoxEntriesLabel.Text = string.Empty;
    for (int i = 0; i < 10; i++)
    {
        string textBoxId = string.Format("TextBox{0}", i);
        TextBoxEntriesLabel.Text += string.Format("TextBox: {0}, Value: {1}
", textBoxId, TextBoxCollection1.GetTextBox(textBoxId).Text);
    }
}

Hope this helps.