FindControl() returns null when searching for dynamic contro

In my requirement I am creating dynamic controls by two events

Dropdownlist OnSelectedIndexChanged event
Onclick button event

In OnSelectedIndexChanged event i have created number of dynamic textbox.

Here I have create two dynamic textboxes.

I am getting all enquiry product list based on enquiry number from the dynamic textboxes on button click event

All are dynamic controls

While saving the productlist the checkbox control return null value

protected void ddlenqChaged(object sender, EventArgs e)
{
getenqTextbox();
}
protected void btnSearchClick(object sender, EventArgs e)
{
tblbill.Visible = true;
if (Convert.ToString(ViewState["Generated"]) != "true")
{
CreateDynamicControls();
ViewState["Generated"] = "true";
}
}
protected void getenqTextbox()
{
enqPanel.Controls.Clear();
if (Convert.ToInt32(ddlNoofEnq.SelectedValue) > 0)
{
for (int i = 1; i <= Convert.ToInt32(ddlNoofEnq.SelectedValue); i++)
{
TextBox _txtCode = new TextBox();
_txtCode.ID = "txtEnqqNo" + i;
_txtCode.Attributes.Add("ClientIDMode", "Static");
_txtCode.Width = 75;
_txtCode.CssClass = "AtCompleteByEnq";
enqPanel.Controls.Add(_txtCode);
}
}
}
protected void CreateDynamicControls()
{
int m = 1;
//int encount = click.buttonclick;
if (Convert.ToInt32(ddlNoofEnq.SelectedValue) > 0)
{
Table tbldynamic = new Table();
for (int k = 1; k <= Convert.ToInt32(ddlNoofEnq.SelectedValue); k++)
{
Panel1.Controls.Clear();
TextBox tb = (TextBox)enqPanel.FindControl("txtEnqqNo" + k);
if (tb != null)
{
if (!String.IsNullOrEmpty(tb.Text))
{
List objlst = Enquiry_ProductListBLL.GetEnquiry_ProductListBLLs(tb.Text);
foreach (Enquiry_ProductListBLL item in objlst)
{
TableRow tr = new TableRow();
TableCell tc = new TableCell();
TableCell tc1 = new TableCell();
TableCell tc2 = new TableCell();
TableCell tc3 = new TableCell();
TableCell tc4 = new TableCell();
TableCell tc5 = new TableCell();
TableCell tc6 = new TableCell();
Master_ProductBLL objpdt = Master_ProductBLL.GetMaster_ProductBLL(item.ProductId);
CheckBox _chkRowNo = new CheckBox();
_chkRowNo.ID = "chkRowNo" + m;
_chkRowNo.Text = m.ToString();
_chkRowNo.Attributes.Add("ClientIDMode", "Static");
_chkRowNo.Attributes.Add("onclick", "getEnable(this);");
_chkRowNo.Checked = true;
TextBox _txtCode = new TextBox();
_txtCode.ID = "txtCodeRow" + m;
_txtCode.Attributes.Add("ClientIDMode", "Static");
_txtCode.Enabled = false;
_txtCode.Width = 75;
_txtCode.Attributes.Add("autocomplete", "off");
_txtCode.Text = objpdt.Code;
HiddenField _hdnPdtId = new HiddenField();
_hdnPdtId.ID = "hdnPdtId" + m;
_hdnPdtId.Value = item.ProductId.ToString();
HiddenField _hdEnqNo = new HiddenField();
_hdEnqNo.ID = "hdEnqNo" + m;
_hdEnqNo.Value = item.EnqNo;
_hdnPdtId.Value = item.ProductId.ToString();
TextBox _txtPdtName = new TextBox();
_txtPdtName.ID = "txtPdtNameRow" + m;
_txtPdtName.Attributes.Add("ClientIDMode", "Static");
_txtPdtName.Enabled = false;
_txtPdtName.Width = 150;
_txtPdtName.CssClass = "AtCompleteByName";
_txtPdtName.Text = objpdt.Name;
TextBox _txtQty = new TextBox();
_txtQty.ID = "txtQtyRow" + m;
_txtQty.Width = 80;
_txtQty.MaxLength = 8;
_txtQty.Attributes.Add("ClientIDMode", "Static");
_txtQty.Text = item.Count.ToString();
DropDownList ddlUnits = new DropDownList();
ddlUnits.ID = "ddlUnits" + m;
ddlUnits.CssClass = "dropdowncss";
ddlUnits.Width = 100;
Bindings.BindUnitName(ddlUnits);
ddlUnits.Items.FindByText(item.PP).Selected = true;
tc.Controls.Add(_chkRowNo);
tc1.Controls.Add(_txtCode);
tc2.Controls.Add(_txtPdtName);
tc2.Controls.Add(_hdnPdtId);
tc2.Controls.Add(_hdEnqNo);
tc3.Controls.Add(_txtBrand);
tc4.Controls.Add(_txtThickness);
tc5.Controls.Add(ddlUnits);
tc6.Controls.Add(_txtQty);
tc.Attributes.Add("Width", "50px");
tr.Attributes.Add("id", "Rowid" + m);
tr.Attributes.Add("class", "paidRw");
tr.Cells.Add(tc);
tr.Cells.Add(tc1);
tr.Cells.Add(tc2);
tr.Cells.Add(tc3);
tr.Cells.Add(tc4);
tr.Cells.Add(tc5);
tr.Cells.Add(tc6);
tbldynamic.Rows.Add(tr);
m++;
}
}
}
}
Panel1.Controls.Add(tbldynamic);
}
}

Here I have override OnLoad event

protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
CreateDynamicControls();
getenqTextbox();
}

My problem is i cannot find controls from Panel1

CheckBox chk = (CheckBox)Panel1.FindControl(chkId);
if (chk != null)
{
if (chk.Checked == true)
{
//my process
}
}

FindControl returns null value.

Here I have create dynamic controls two times.

I cannot have any problem with enquiry textbox, it was created first, but the second time button click event controls are return null.

4 Replies

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theLizard8y ago
I could be wrong BUT everywhere you use an int value to append to a string value, example: _txtCode.ID = "txtEnqqNo" + i;

you do not convert the int value to a string value so when you go to find the control you are looking for it does not exist.

In this case - TextBox tb = (TextBox)enqPanel.FindControl("txtEnqqNo" + k);
k is an int value, you are asking to find "txtEnqqNo", a string value.

Because you do not convert k to a string value, the FindControl is effectively looking for "txtEnqqNo" which does not exist therefore I am guessing that is why you are getting a null value error

try something like _txtCode.ID = "txtEnqqNo" + i.ToString();
0
hisanth nithi8y ago
1. for (int i = 1; i <= count; i++)
2. {
3. String chkId = "chkRowNo" + i;
4. CheckBox chk = (CheckBox)Panel1.FindControl(chkId);
5. if (chk != null)
6. {
7. if (chk.Checked == true)
8. {
10. }
11. }
12. }
0