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Create checkbox next to each label

I need this page to be very easily maintained, so I need most of the stuff to be programmatically generated. I need to create checkboxes next to normal Labels, without touching the .aspx file. right now I generate a list with all labels on my page called labels. Each label on my site has an ID beginning with lbl_, but the ones that are supposed to have a checkbox begin with lblx_. I then want to use something like this to create said checkboxes:
foreach (Label label in labels)
{
if (label.ID.Contains("lblx_"))
{
CheckBox cb = new CheckBox();
cb.ID = "cb_statistikname_" + label.ID;
label.Controls.AddAt(0, cb);
}
}
Right now this code replaces the labels, the same happens when I use label.Control.Add(cb)

You can use Page.Controls.AddAt() with combination of page.Page.Controls.IndexOf()
if(label.Parent != null && label.Parent.Controls.IndexOf(label) >= 0)
label.Parent.Controls.AddAt(label.Parent.Controls.IndexOf(label) + 1, cb);
Note :This should be done in Page PreInit events.

If you set the Text property in your Label control, basically all child controls get wiped out. See this answer: asp:label doesn't render children

Removing Items From Panel on a Timer

Background
I have a table of items that the user can edit. They can navigate through the fields with the arrow keys, and the information in the current row is saved when they move to a new one. The project requires a notification be displayed to the user when the row was successfully saved, and my boss requires me to do this through Bootstrap alerts.
One alert needs to be created for each successful save, and if the user saves multiple rows in a short time they should stack inside of a panel. Because the number of alerts is unknown, I'm dynamically adding them to the page from the code-behind. Each alert is made up of a panel and a label, which is being added to a larger panel that holds all the alerts. This part I've got figured out -- the alerts show up when they're supposed to, and in the correct numbers.
The problem is that each alert is only supposed to show on the screen for a limited amount of time. This is somewhere between two and five seconds, to be determined by my boss at a later date. My idea was to start a timer for two seconds each time an alert is created, and remove the first alert from the panel when the timer finished. Because no two timers would be created at exactly the same time, this should theoretically remove each alert two seconds after it appears, stopping once the last alert is gone. Unfortunately for me, that isn't how it's working.
Instead, I get an 'index out of bounds' exception, indicating that the alert I'm trying to remove doesn't actually exist. But it does exist -- I can see it on my screen. So I'm not sure what's going wrong.
Code
Creation of Alerts
This code is inside of Page_Load, so that the alerts are still visible on postback.
if (Session["success"] != null)
{
int test = Convert.ToInt32(Session["success"]);
for(int a = 1; a <= test; a++)
{
Panel alert = new Panel();
alert.CssClass = "alert alert-success";
alert.ID = "dynamicAlert" + a;
alert.Attributes["role"] = "alert";
Label innerAlert = new Label();
innerAlert.ID = "dynamicAlertInner" + a;
innerAlert.Text = "<strong>Success!</strong> Your row was saved.";
alert.Controls.Add(innerAlert);
alertsUpdate.ContentTemplateContainer.FindControl("pnlAlerts").Controls.Add(alert);
System.Timers.Timer time = new System.Timers.Timer(2000);
time.Elapsed += removeAlert;
time.Start();
}
}
Deletion of Alerts
The removeAlert method is intended to remove the alert at index 0 from the panel contained within the update panel.
private void removeAlert(Object source, System.Timers.ElapsedEventArgs e)
{
Panel pnl = (Panel)alertsUpdate.ContentTemplateContainer.FindControl("pnlAlerts");
if(pnl != null && pnl.Controls.Count > 0)
{
pnl.Controls.RemoveAt(0);
}
}

tabcontrol not refreshing

I have a TabControl that starts with three TabPages in it. On the first tab there is a NumericUpDown (spinner) which displays the number of tabs and allows a user to add up to 10 extra tabs. Once they add more than about 5 or 6 it goes beyond the width of the form and the rest of the tabs are accessible by a couple of left/right arrows at the top. When going all the way to the right and then using the spinner to go back down to 0 (removing all the extra tabs and leave the starting three) it removes all tabs from the top of the pane and only by setting the spinner back to 1 does it refresh and display all 4 (3 from the start plus the 1 from the spinner).
I have tried several commbinations of
Application.DoEvents()
this.Refresh()
this.Invalidate()
this.Update()
but nothing seems to work. can anybody suggest a reason why it is not updating/refreshing?
public partial class Form1 : Form
{
TabPage[] tabs;
public Form1()
{
InitializeComponent();
tabs = new TabPage[tabControl1.Controls.Count];
tabs[0] = tabPage1;
}
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
int numTabs = tabControl1.Controls.Count;
decimal spinnerValue = numericUpDown1.Value;
if (numTabs < spinnerValue) //add a tab
{
TabPage[] newTabs = new TabPage[(int)spinnerValue];
for (int i = 0; i < numTabs; i++)
{
newTabs[i] = tabs[i];
}
TabPage tab = new TabPage("Tab " + numTabs);
newTabs[(int)spinnerValue-1] = tab;
tabControl1.Controls.Add(tab);
tabs = newTabs;
}
else //remove a tab
{
TabPage[] newTabs = new TabPage[(int)spinnerValue];
for (int i = 0; i < spinnerValue; i++)
{
newTabs[i] = tabs[i];
}
tabControl1.Controls.Remove(tabs[(int)spinnerValue]);
tabs = newTabs;
}
}
}

Without seeing any code or knowing what type of project this is winforms, WPF, ASP.NET etc..
it's hard to give a definite answer, I am going to assume that this is WinForms
I'm not sure if you can. The following is a quote from MSDN:
"Controls contained in a TabPage are not created until the tab page is shown, and any data bindings in these controls are not activated until the tab page is shown."
However, instead of having the update code get the values from the controls directly, maybe you could create a class that could hold the Data you use to populate the controls and then when the update code is called it asks the class for the value and the class checks if the control is loaded and otherwise it gets the value from the Data instead.

Add multiple controls to panel in webforms

I would like to be able to add multiple label controls to a panel and display them on an onlick event. The code I have does what I want it to the first time, then the label is simple replaced with a new label on the second onlick event and so on.
Here is what I have so far:
private void createTaskLabel(Guid GoalID, string Goal)
{
Label taskLabel = new Label();
taskLabel.ID = GoalID.ToString();
taskLabel.Text = Goal.ToString();
TaskPanel.Controls.Add(taskLabel);
}
So, for instance, this creates a new label with a uniqueID (handled elsewhere) and places it within the panel and displays it. When the onlick fires again, the same label is simply replaced instead of a new one appearing below it.

Dynamically created controls are not persisted after a postback. You need to keep track of how many controls you have generated and regenerate ALL of them each time for this to work how you want. Basic implementation:
List<string> LabeIDList = new List<string>();
override SaveViewState(..)
{
if (LabelIDList.Count>0) {
ViewState["LabelDIList"]=LabelIDList;
}
base.SaveViewState(..)
}
override LoadViewState()
{
base.LoadViewState();
if (ViewState["LabelIDList"]!=null) {
LabelIDList = (List<string>)ViewState["LabelIDList"];
}
}
override void OnLoad(..)
{
foreach (string id in LabelIDList)
{
// Make a function essentially like your code in createTaskLabel,
// you can use it there too
RecreateControl(id);
}
}
private void createTaskLabel(Guid GoalID, string Goal)
{
...
// save the ID you just created
LabelIDList.Add(taskLabel.ID);
}
I just realized that these are Labels you're creating - so actually you should probably be keeping track of the Text instead of the ID. If the actual ID is important for some reason then keep track of them both, use a List<Tuple<string,string>> for that. More typical situation is creating input controls, though, in which case ASP.NET will persist the data that a user entered as long as you re-create them on or before OnLoad (assuming ViewState enabled).

Dim lbl As New Label
Dim lbl1 As New Label
Dim txt As New TextBox
Dim txt1 As New TextBox
lbl.Text = "Name"
lbl1.Text = "class"
Me.Controls.Add(lbl)
Me.Controls.Add(txt)
Me.Controls.Add(lbl1)
Me.Controls.Add(txt1)

Have you look at Repeater control? It might make it a bit easier to implement I think.
At least you don't need to worry about the label control creations yourself.

Dynamic control click event not firing properly

I'm creating a next/previous function for my repeater using pageddatasource. I added the link button control dynamically in my oninit using the following code.
LinkButton lnkNext = new LinkButton();
lnkNext.Text = "Next";
lnkNext.Click += new EventHandler(NextPage);
if (currentPage != objPagedDataSource.PageCount)
{
pnlMain.Controls.Add(lnkNext);
}
So in my initial page_load, the next link comes up fine. There are 5 pages in my objPagedDataSource. currentPage variable is 1.
The "NextPage" event handler looks like this
public void NextPage(object sender, EventArgs e)
{
if (HttpContext.Current.Request.Cookies["PageNum"] == null)
{
HttpCookie cookie = new HttpCookie("PageNum");
cookie.Value = "1";
}
else
{
HttpCookie cookie = HttpContext.Current.Request.Cookies["PageNum"];
cookie.Value = (Convert.ToInt32(cookie.Value) + 1).ToString();
}
this.BindRepeater();
}
So I am incrementing the cookie I am using to track the page number and then rebinding the repeater.
Here is the main issue. The first time I click Next, it works, it goes to Page 2 without any problems. When on Page 2, I click Next, it goes back to Page 1. Seems like the Next event is not wiring up properly. Not sure why, any ideas?

You need to ensure you're adding your dynamic control to the Page every postback. Dynamic controls often cause much pain - in this case it would probably be much easier to declare the "Next" LinkButton in the markup in the normal way, and just set Visible = false when it isn't required.

While you are loading user controls dynamically you must set ID property without ID property Events will not fire.This is My sample code to call user controls dynamically
private void LoadUserControl()
{
string controlPath = LastLoadedControl;
if (!string.IsNullOrEmpty(controlPath))
{
PlaceHolder1.Controls.Clear();
UserControl uc = (UserControl)LoadControl(controlPath);
uc.ID = "uc"; //Set ID Property here
PlaceHolder1.Controls.Add(uc);
}
}