Iterating through textboxes using asp.net

Question

I am building a page with asp.net. I have a form with a table that contains TextBoxes and a submit button. When the form is submitted, I want to grab all the text that was entered into the TextBoxes and operate on them. To do this, I have the following method:

protected void Button1_Click(object sender, EventArgs e)
{
    System.Text.StringBuilder sb = new System.Text.StringBuilder();

    foreach (Control c in this.Controls)
    {
        if (c.GetType().Name == "TextBox")
        {
            TextBox tb = (TextBox)c;
            sb.AppendLine(tb.Text);
        }
    }
    Label1.Text = sb.ToString();
}

The problem with this is that the controls apparently doesn't include any of my textboxes. When I iterate through the controls and print out their names, the only one I get is "site_master." (I also tried Controls and Page.Controls instead of this.Controls).

Is there something wrong with my iterator? Is there another way in which I could iterate through all of the textboxes in the table or page? What is the best way to accomplish this?

Try this.Form.Controls. Your textboxes are basically nested in another container, you need to query the controls of that container. — Anthony Pegram
– Anthony Pegram, Commented Jun 2, 2011 at 23:24

Nick Rolando · Accepted Answer · 2011-06-02 23:22:27Z

4

Would it be too much to build a List<Textbox>, given you know all your textbox controls?

List<Textbox> txtBoxes = new List<Textbox>();
txtBoxes.Add(tb1);
txtBoxes.Add(tb2);
//etc..

Then you have a nice list to work with

answered Jun 2, 2011 at 23:22

Nick Rolando

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Comments

Anthony Pegram · Accepted Answer · 2011-06-02 23:38:56Z

If I knew the controls were all in a given containing control, I would simply poll the controls of that control. For example, this.Form.Controls. However, if they could be nested within other child controls, then you could recursively explore the depths from a common outer container.

private IEnumerable<T> FindControls<T>(Control parent) where T : Control
{
    foreach (Control control in parent.Controls)
    {
        if (control is T)
            yield return (T)control;

        foreach (T item in FindControls<T>(control))
            yield return item;
    }
}

So this would allow you to retrieve all TextBox children.

List<TextBox> textBoxes = this.FindControls<TextBox>(this).ToList();
string output = string.Join(",", textBoxes.Select(tb => tb.Text));

Ken Henderson · Accepted Answer · 2011-06-02 23:27:45Z

I'm going to assume that you are using web forms ASP.NET. Typically you declare your controls on the aspx page using something similar to

<asp:TextBox ID="someId" runat="server/>

If you have done this then in your code behind your should just be able to reference the variable someId and the property Text to get/set the text in the control.

If you are building the controls dynamically on the server you should be able to stick them in a list and iterate through it. Make sure you are creating the controls and adding them to the table during the correct part of the page lifecycle. When you add them to a cell in the table you could also keep a reference to the control in a list and just enumerate through that list in your event handler.

Maybe something along the lines of (I didn't compile this so there are probably issues):

public class MyPage: Page
{
  private List<TextBox> TxtBoxes = new List<TextBox>();

  //registered for the preinit on the page....
  public void PreInitHandler(object sender, EventArgs e)
  {
      for(var i = 0; i < 2; i++)
      {
        var txtBox = new TextBox{Id = textBox+i};
        //...add cell to table and add txtBox Control
        TxtBoxes.Add(txtBox);
      }
  }
}

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