How to Create Dynamically Generated TextBoxes in ASP.NET - asp.net

Question

I have this code which generates TextBoxes in a Table dynamically, I got it from a website:
protected void AddStdBtn_Click(object sender, EventArgs e)
{
CreateDynamicTable();
}
private void CreateDynamicTable()
{
// Fetch the number of Rows and Columns for the table
// using the properties
if (ViewState["Stu"] != null)
Students = (DataTable)ViewState["Stu"];
int tblCols = 1;
int tblRows = Int32.Parse(NoTxt.Text);
// Now iterate through the table and add your controls
for (int i = 0; i < tblRows; i++)
{
TableRow tr = new TableRow();
for (int j = 0; j < tblCols; j++)
{
TableCell tc = new TableCell();
TextBox txtBox = new TextBox();
txtBox.ID = "txt-" + i.ToString() + "-" + j.ToString();
txtBox.Text = "RowNo:" + i + " " + "ColumnNo:" + " " + j;
// Add the control to the TableCell
tc.Controls.Add(txtBox);
// Add the TableCell to the TableRow
tr.Cells.Add(tc);
}
// Add the TableRow to the Table
tbl.Rows.Add(tr);
tbl.EnableViewState = true;
ViewState["tbl"] = true;
}
}
protected void CalculateBtn_Click(object sender, EventArgs e)
{
foreach (TableRow tr in tbl.Controls)
{
foreach (TableCell tc in tr.Controls)
{
if (tc.Controls[0] is TextBox)
{
Response.Write(((TextBox)tc.Controls[0]).Text);
}
}
Response.Write("<br/>");
}
}
protected override object SaveViewState()
{
object[] newViewState = new object[2];
List<string> txtValues = new List<string>();
foreach (TableRow row in tbl.Controls)
{
foreach (TableCell cell in row.Controls)
{
if (cell.Controls[0] is TextBox)
{
txtValues.Add(((TextBox)cell.Controls[0]).Text);
}
}
}
newViewState[0] = txtValues.ToArray();
newViewState[1] = base.SaveViewState();
return newViewState;
}
protected override void LoadViewState(object savedState)
{
//if we can identify the custom view state as defined in the override for SaveViewState
if (savedState is object[] && ((object[])savedState).Length == 2 && ((object[])savedState)[0] is string[])
{
object[] newViewState = (object[])savedState;
string[] txtValues = (string[])(newViewState[0]);
if (ViewState["Stu"] != null)
Students = (DataTable)ViewState["Stu"];
if (txtValues.Length > 0)
{
//re-load tables
CreateDynamicTable();
int i = 0;
foreach (TableRow row in tbl.Controls)
{
foreach (TableCell cell in row.Controls)
{
if (cell.Controls[0] is TextBox && i < txtValues.Length)
{
((TextBox)cell.Controls[0]).Text = txtValues[i++].ToString();
}
}
}
}
//load the ViewState normally
base.LoadViewState(newViewState[1]);
}
else
{
base.LoadViewState(savedState);
}
}
Now if you examine CreateDynamicTable() function, particularly the line:
int tblRows = Int32.Parse(NoTxt.Text);
you can see that the user can control the number of rows by entering a number in the TextBox NoTxt. When I run this code I get the following error:
An exception of type 'System.FormatException' occurred in mscorlib.dll but was not handled in user code
Additional information: Input string was not in a correct format.
and the error location is in the same line above.
The question is: How can I let the user control the number of rows in the table?

Answer 1

After few days of reading and research, the solution can be done by using Session variables. Store the value obtained in NoTxt.Text as follows for example:
Session["V"] = Int32.Parse(NoTxt.Text);
and retrieve it once you need it.