在asp.NET C＃中寻址动态创建的TextBox控件

Question

I'm trying to make a page that loads an undefined number of rows into a table, each row containing two columns, one column a string, the other a TextBox. When I click a submit button, i want to be able to retrieve the values entered into each TextBox.

The first half i can do, obviously in the real code this would be in a foreach loop and the textbox ID assigned a unique value i could reproduce later to call it with.

TableCell myCell = new TableCell();
myCell.Text = "StudentID";
TableCell nextCell = new TableCell();
TextBox mytext = new TextBox();
mytext.ID = "TxtBox1";
nextCell.Controls.Add(mytext);
TableRow myRow = new TableRow();
myRow.Cells.Add(myCell);
myRow.Cells.Add(nextCell);
TableStuUploads.Rows.Add(myRow);

When i click my submit button, i try to run this code(just temp code ATM, proof of concept stuff):

TextBox tmptext = (TextBox)FindControl("TxtBox1");
Label1.Text = tmptext.Text;

But that sets tmptext as null, and i get a null pointer exception on the next line. So then i tried

TextBox tmptext = (TextBox)TableStuUploads.FindControl("TxtBox1");
Label1.Text = tmptext.Text;

Same error. Then i tried

foreach (Control x in TableStuUploads.Controls)
            {
                if (x.GetType().ToString().Equals("System.Web.UI.WebControls.TextBox"))
                {
                    Label1.Text = ((TextBox)x).Text;

                }
            }

But when debugging this, I see TableStuUploads.Controls has a count of zero.

How am I supposed to address these dynamically created controls? I have searched around, and the answer i got lead me to the three solutions i have already tried. Where am i going wrong?

Answer 1

You are probably not recreating your dynamic controls on post back. This is required to both find each control and retrieve each control's value.

In addition, it would probably be best to use a repeater to create these controls, It is easier to maintain and debug.

Answer 2

Edit

You need to recreate your table on each postback(page_load) like @ShaiCohen says in his answer then you need something ilke:

foreach (TableRow item in TableStuUploads.Rows)
{               
     TextBox tmptext = (TextBox)item.FindControl("TxtBox1");
     Label1.Text = tmptext.Text;
}