adding textboxes at runtime in asp.net

Question

i need to create textboxes dynamically as user specifies the no..actually there are two textboxes in a row..user specifies no of rows needed.. as specified textboxes(two per row) should be added to the form and also i need to read the text entered later....what is the best method??

Answer 1

If the number of textboxes is constant but the number of rows is dynamic, then use a GridView. Then bind the gridview to a list or array of the length that the user specified. The gridview will then render the specified rows and you can get the values from the textboxes on postback.

Answer 2

Control.Controls.Add(new TextBox());

Notes:

• "Control" will obviously be the parent control of where the textboxes go in your case, e.g. an control.
• You'll need to add the controls on CreateChildControls or on Page_Init so they are added at the right point in the page lifetime.

Answer 3

To add controls to an aspx page dynamically, follow these steps.

First, add a placeholder on the ASPX page:

<asp:PlaceHolder runat="server" id="AssessCanvas" />

Mine is called "AssessCanvas". Next, add the controls themselves. Here is code that I use in methods called by Page_Load to create a label and a text box. The label is a prompt for "Weight:" and the text box is used to enter a weight value (in the example, I am also including a value for weight when I create the box):

Label aLbl = new Label { Text = "Weight: ", ID = ("WSLabel" + counter) };
counter++;
AssessCanvas.Controls.Add(aLbl);

TextBox aBox = new TextBox { ID = "XTest1", Columns = 5, Text = weight.ToString("##0.0"), Width = 50 };
AssessCanvas.Controls.Add(aBox);

I use "WSLabelN" (where N is a number) to give a unique ID to each label. Because I'll want to scan all of my text boxes to pull their contents when the form is submitted, I give each of them an ID of the form "XTestN" (where N is a unique identifier for each field - here the "XTest1" tells me that this is the weight field).

When I'm ready to handle the form submit, I do this:

// Look at each key submitted with the form - *some* of these will be my input text boxes
foreach (string aStr in form.AllKeys)
{
    // Is this an input text box?  Yes if it has "XTest" in it somewhere.
    int position = aStr.IndexOf("XTest");
    if (position > 0)
    {
        // The data entry fields for each input box follows the format: <ASP.NET Prefix>XTest<TID>
        // Here I get the tid so I know what to do with the value that was entered 
        short tid = BSDIUtil.StrToIntDef(aStr.Substring(position + 5));
        switch (tid)
        {
            case 1: SaveWeight(BSDIUtil.StrToFloatDef(form.Get(aStr))); break;
            case 2: SaveJP3P1(BSDIUtil.StrToFloatDef(form.Get(aStr))); break;
            ... etc...
         }
     }
}

In my system, I often have to place several fields on the page to collect values for one testing item (the system here comes from a fitness testing page). For example, "SaveJP3P1" above isn't called as shown because it actually pulls data from nine different fields. I simplified it for the example for obvious reasons.

This approach gives you a great deal of flexibility. In my full page, I have check-boxes, header labels (e.g. a label with HTML/CSS formatting in addition to the label text), and even several DIVS for fitness tests with multiple panels for their input. And all of it is done dynamically. Obviously, a grid wouldn't work and neither would just adding a control to the control tree as others have suggested.