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ASP.Net WebForms LinkButton click, open new tab, passing id through hidden html input variable

I have an aspx webforms page with a repeater built through a user control. Each repeater item has a link button. What I want to happen is that when the LinkButton (in the repeater on page A's user control) is clicked, the url is opened in a new tab, and a hidden id next to that LinkButton is passed (according web development best practices for security if possible) to the aspx page (page B) in the new tab. Both pages A and page B are in the same application.The intent of what I described above is so that the user can easily return to their search results after returning from the URL opened by clicking on the LinkButton.I am open to ideas on how to do this that are closer to standard best-practice methods.
So far, I have tried:
1) cross-page posting – this worked for passing the id, but not for opening in a new tab.
2) Setting the PostBackUrl to page B's url, setting the Page.Form.Target="_blank" with OnClientClick calling javascript to set the hidden id from the user control to the value of an html hidden input on page B and also.
3) I also tried using window.open("page B url", "_newtab") in OnClientClick.
a) So far, the only method that worked correctly was the 2nd one from the 3 different methods above. However, after page B is loaded in the new tab, I don't know how to reset page A's Page.Form.Target back to what it was previously before setting it to "_blank"
b) The methods that I have tried, to no avail, to reset the Page.Form.Target have been:
1) Resetting the target in page A's Page_Load where IsPostBack == true --> that caused Page B to load with the same content as Page A.
2) Resetting the target in page A's user control's Page_Load --> same result as method 1
3) Resetting the target in page A’s user control’s LinkButton’s OnUnLoad in page A's user control --> same result as method 1
4) Resetting the target in javascript through the LinkButton’s OnClientClick --> didn’t work
5) Resetting the target in page B's Page_Load using a public variable from page A containing a reference to page A's form (similar to what can be done through cross-page posting) --> didn’t work.
What I am thinking about trying next is:
1) Wrapping another user control on page A to display page B's content, in an asp Panel (Panel B)
2) Put page B’s content into the new user control page
3) Wrapping the search results content on page A in an asp Panel (Panel A).
4) When the LinkButton in the repeater on the new user control is clicked, the search results content in Panel A will be hidden, and Panel B will be shown.
5) When the user wants to return to the search results, they will click on a ‘Return to Search’ LinkButton in Panel B’s content, and then Panel B will be hidden, then content of Panel B will be cleared, and Panel A will be shown again.
I'm not yet sure if that will work though. It doesn't seem like this should be that difficult. It is a straight-forward concept, and I would think is a fairly common situation in web development.
I feel like Wiley Coyote trying to catch the Road Runner because I come up with elaborate intelligent, thought-out plans that all completely fail. I am now holding up a little sign that says, "Help!

I had the same issue resolve by the following code you just try this in ur HTML page for a button in GRIDVIEW:
<asp:LinkButton ID="LinkButton1" runat="server" Text="View" CommandArgument='<%# Bind("ref") %>'
OnClick="LinkButton1_Click" OnClientClick="document.forms[0].target ='_blank';">View</asp:LinkButton>***

I actually got this figured out.
I figured it out through a combination of the marked-answer on this post, How to Open new tab when we click on LinkButton, and the marked-answer on this post, Is it possible add click event to hyperlink?.
My Repeater ItemTemplate in the user control's repeater looks similar to this:
<asp:HiddenField ID="hfId" runat="server"
Value='<%# Eval("Id") %>'/>
<asp:HyperLink ID="myLink" runat="server"
Text='<%# Eval("Name") %>'
NavigateUrl="/myUrl.aspx"
Target="_blank" />
<asp:Button ID="btnSubmit" runat="server"
Text="Submit"
OnClick="BtnClick"
Style="display: none;" />
This is my code in the ItemDataBound of the repeater:
protected void RptrItemDataBound(object sender, RepeaterItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
{
var myId = "";
var myNameLink = e.Item.FindControl("myLink") as HyperLink;
if (myNameLink != null)
{
var submitButton = e.Item.FindControl("btnSubmit") as Button;
if (submitButton != null)
{
var submitButtonClientId = submitButton.ClientID;
myNameLink.Attributes.Add("onclick", "onNameClick('" + submitButtonClientId + "')");
}
}
}
}//end RptrItemDataBound
The javascript code:
<script type="text/javascript">
function nameClick(buttonId)
{
document.getElementById(buttonId).click();
}
</script>
And here is the BtnClick C# code:
protected void BtnClick(object sender, EventArgs e)
{
var btnSelect = sender as Button;
if (btnSelect == null)
{
return;
}
var myListItem = (RepeaterItem)btnSelect.DataItemContainer;
if (myListItem != null)
{
var hfId = myListItem.FindControl("hfId") as HiddenField;
if (hfId != null)
{
var intId = int.Parse(hfId.Value);
Session["selectedId"] = intId;
}//end if (hfId != null)
}//end if (myListItem != null)
}//end btnClick

How to check whether postback caused by a Dynamic link button

I have a button control. On click of this button I need to add a Link Button dynamically. The Link Button needs an event handler. Hence the dynamic Link button is first added in the Page_Load and cleared and added again in the button click handler. Please read Dynamic Control’s Event Handler’s Working for understanding the business requirement for this.
I have read On postback, how can I check which control cause postback in Page_Init event for identifying the control that caused the postback (inside Page_Load). But it is not working for my scenario.
What change need to be done to confirm whether the postback was caused by link button (inside Page_Load)?
Note: Refer the following for another scenario where it is inevitable https://codereview.stackexchange.com/questions/20510/custom-paging-in-asp-net-web-application
Note 1: I need to get the postback control ID as the first step inside if (Page.IsPostBack). I need to add the dynamic link buttons control only if it is a postback from the button or the link button. There will be other controls that causes postback. For such postbacks we should not execute this code.
Note 2: I am getting empty string for Request["__EVENTARGUMENT"] in the Page_Load
Related Question: By what event, the dynamic controls will be available in the Page (for using in FindControl). #Tung says - "Your GetPostBackControlId method is properly getting the name of the control that caused the postback, but it is unable to find a control with that id through page.FindControl because the linkbutton has not been created yet, and so page does not know of its existence. "
ASPX
<%# Page Language="C#" AutoEventWireup="true" CodeFile="PostbackTest.aspx.cs" Inherits="PostbackTest"
MasterPageFile="~/TestMasterPage.master" %>
<asp:Content ID="myContent" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<div id="holder" runat="server">
</div>
<asp:Button ID="Button1" runat="server" Text="Button" OnClick="TestClick" />
</asp:Content>
CODE BEHIND
public partial class PostbackTest : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if(Page.IsPostBack)
{
string IDValue = GetPostBackControlId(this.Page);
int x = 0;
holder.Controls.Clear();
LinkButton lnkDynamic = new LinkButton();
lnkDynamic.Click += new EventHandler(LinkClick);
lnkDynamic.ID = "lnkDynamic123";
lnkDynamic.Text = "lnkDynamic123";
holder.Controls.Add(lnkDynamic);
}
}
protected void TestClick(object sender, EventArgs e)
{
holder.Controls.Clear();
LinkButton lnkDynamic = new LinkButton();
lnkDynamic.Click += new EventHandler(LinkClick);
lnkDynamic.ID = "lnkDynamic123";
lnkDynamic.Text = "lnkDynamic123";
holder.Controls.Add(lnkDynamic);
}
protected void LinkClick(object sender, EventArgs e)
{
}
public static string GetPostBackControlId(Page page)
{
if (!page.IsPostBack)
{
return string.Empty;
}
Control control = null;
// First check the "__EVENTTARGET" for controls with "_doPostBack" function
string controlName = page.Request.Params["__EVENTTARGET"];
if (!String.IsNullOrEmpty(controlName))
{
control = page.FindControl(controlName);
}
else
{
// if __EVENTTARGET is null, the control is a button type
string controlId;
Control foundControl;
foreach (string ctl in page.Request.Form)
{
// Handle ImageButton they having an additional "quasi-property" in their Id which identifies mouse x and y coordinates
if (ctl.EndsWith(".x") || ctl.EndsWith(".y"))
{
controlId = ctl.Substring(0, ctl.Length - 2);
foundControl = page.FindControl(controlId);
}
else
{
foundControl = page.FindControl(ctl);
}
if (!(foundControl is Button || foundControl is ImageButton)) continue;
control = foundControl;
break;
}
}
return control == null ? String.Empty : control.ID;
}
}
REFERENCE
On postback, how can I check which control cause postback in Page_Init event
Dynamic Control’s Event Handler’s Working
Understanding the JavaScript __doPostBack Function
Access JavaScript variables on PostBack using ASP.NET Code
How does ASP.NET know which event to fire during a postback?
how to remove 'name' attribute from server controls?
How to use __doPostBack()

A postback in asp.net is done by the java script function __doPostback(source, parameter)
so in your case it would be
__doPostback("lnkDynamic123","") something like this
So in the code behind do the following
var btnTrigger = Request["__EVENTTARGET"];
if(btnTrigger=="lnkDynamic123")
{
}
--- this would tell that it is your linkbutton that causes the postback

You can move the call to the GetPostBackControlId method after the LinkButton has been added to the page:
protected void Page_Load(object sender, EventArgs e)
{
if (Page.IsPostBack)
{
holder.Controls.Clear();
LinkButton lnkDynamic = new LinkButton();
lnkDynamic.Click += new EventHandler(LinkClick);
lnkDynamic.ID = "lnkDynamic123";
lnkDynamic.Text = "lnkDynamic123";
holder.Controls.Add(lnkDynamic);
string IDValue = GetPostBackControlId(this.Page);
if (IDValue == lnkDynamic.ID)
LinkClick(lnkDynamic, new EventArgs());
}
}
Calling the click event handler here also more closely mimics the standard ASP.NET Page Life Cycle, where Postback event handling occurs after the Load event.
Edit:
If the control ID must be determined before the LinkButtons are created, you can create a naming scheme for the link button IDs, e.g. lnkDynamic_1, lnkDynamic_2 etc.
Request["__EVENTTARGET"] will then contain the auto-generated control ID such as “ctl00$mc$lnkDynamic_1”, which you can use to identify which LinkButton caused the postback.

If You're getting the post back control id correctly but FindControl returns nothing, then it's probably because You're using a master page. Basically, someControl.FindControl(id) searches through controls that are in someControl.NamingContainer naming container. But in Your case, the Button1 control is in the ContentPlaceHolder1, which is a naming container, and not directly in the Page naming container, so You won't find it by invoking Page.FindControl. If You can't predict in which naming container the control You're looking for is going to be (e.g. post back can be caused by two different buttons from two different content placeholders), then You can write an extension that'll search for a control recursively, like so:
public static class Extensions
{
public static Control FindControlRecursively(this Control control, string id)
{
if (control.ID == id)
return control;
Control result = default(Control);
foreach (Control child in control.Controls)
{
result = child.FindControlRecursively(id);
if (result != default(Control)) break;
}
return result;
}
}
Use it with caution though, because this method will return the first control that it finds with the specified id (and You can have multiple controls with the same id - but they should be in different naming containers; naming containers are meant to differentiate between controls with same ids, just as namespaces are meant to differentiate between classes with same names).
Alternatively, You could try to use FindControl(string id, int pathOffset) overload, but I think it's pretty tricky.
Also, check this question out.

First approach (wouldn't recommend but it's more flexible)
One completely different approach - although I don't really feel like I should promote it - is to add a hidden field to the form.
The value of this hidden field might be something like false by default.
In case of clicking one of the dynamic buttons which should cause the dynamic controls to be added again, you can simply change the hidden fields value to true on client side before performing the postback (eventually you want/have to modify the client side onclick handler to make this happen).
Of course it would be possible to store more information in such a field, like the controls id and the argument (but you can get those values as described in the other answers). No naming schema would be required in this case.
This hidden field could be "static". So it would be accessible in code behind all time. Anyhow, you might want to implement something to make sure that nobody is playing around with its values and fakes a callback which looks like it originated from one of these dynamic links.
However, this whole approach just helps you getting the id of the control. Until you create the control again, you won't be able to get the instance through NamingContainer.FindControl (as mentioned in the other answers already ;)). And in case you create it, you don't need to find it anymore.
Second approach (might not be suitable due to its contraints)
If you want to do it the clean way, you need to create your controls OnLoad, no matter if something was clicked or not. Additionally, the dynamic controls ID has to be the same as the one you sent to the client in the first place. You subscribe to its Click or Command event and set its visibility to false. Inside the click event handler, you set the senders visibility to true again. This implies, that you don't care if that link is created but instead just don't want to send it to the client. The example below only works for a single link of course (but you could easily modify it to cover a whole group of links).
public void Page_Load(object sender, EventArgs e)
{
LinkButton dynamicButton = new LinkButton();
dynamicButton.ID = "linkDynamic123";
// this id needs to be the same as it was when you
// first sent the page containing the dynamic link to the client
dynamicButton.Click += DynamicButton_Click;
dynamicButton.Visible = false;
Controls.Add(dynamicButton);
}
public void DynamicButton_Click(object sender, EventArgs e)
{
// as you created the control during Page.Load, this event will be fired.
((LinkButton)sender).Visible = true;
}

use code behind to pop aspx confirmation message

I need to return a confirmation message to OnClientClick event. The problem is I have to get the message from stored procedure, and I don't seem to call my function right.
<asp:ImageButton
OnClientClick="return confirm(<%# GetConfirmExportMessage()%>);"
OnClick="btnExportRed_Click"
runat="server"
ImageUrl="~/Images/excel_red.gif"
ID="btnExportRed"
AlternateText="Export all records!"/>
My code behind:
public string GetConfirmExportMessage()
{
string xmlFilterForExport = Parameters.ToString().Split('+')[4].Trim();
string alertMessage = companiesSearcher.GetAlertMessage(xmlFilterForExport, 1, null, null, IdSegment, 1, Convert.ToInt32(RoDB2004.BLL.clsUsers.UserID));
return alertMessage;
}

Try using equal sign instead of pound (and don't forget your single quotes).
OnClientClick="return confirm('<%= GetConfirmExportMessage()%>');"
However, if you're ImageButton is located inside a DataGrid or GridView, the server-side code will not be evaluated and will yeield an alert saying <%= GetConfirmExportMessage()%> instead of the real message.
To get around this problem (and to increase performance, throughput, etc.), output your message once to a variable, then alert the contents of the variable.
<script language="JavaScript">
var myMessage = '<%= GetConfirmExportMessage()%>';
</script>
Later, in the GridView...
OnClientClick="return confirm(myMessage);"
You save throughput by repeating a small variable name like "myMessage" and avoid repeating some big message. Also note, that the method GetConfirmExportMessage isn't called dozens of times increasing performance.
If your message is specific to data within a current row and not static like "Are you sure?", then I suggest you perform this operation inside the GridView's RowDataBound event. You'll have full access to the ImageButton and to the data the current row is binding to, which makes it very easy to setup server-side. Check out the FindControl() method, or if you know the exact location, just reference it and unbox the object.
protected void gvMyGrid_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
ImageButton ibtn = (ImageButton)e.Row.FindControl("btnExportRed");
if(ibtn != null)
{
ibtn.ClientClick = "return confirm('" + GetConfirmExportMessage() + "');";
}
}
}
As an alternative solution, maybe you should look into WebMethods, AJAX and jQuery. This solution is probably the better one because the data is not sent to the client and only retrieved when necessary.

you need to wrap your confirm in '
<asp:ImageButton
OnClientClick="return confirm('<%# GetConfirmExportMessage()%>');"
OnClick="btnExportRed_Click"
runat="server"
ImageUrl="~/Images/excel_red.gif"
ID="btnExportRed"
AlternateText="Export all records!"/>

You probably want
OnClientClick="return confirm('<%= GetConfirmExportMessage()%>');"
Note that this will be populated when the page is rendered, not when the button is clicked, so you may as well use
btnExportRed.OnClientClick = "javascript:return confirm('" + GetConfirmExportMessage() + "');"
in your code behind.

ASP.NET OnClick not firing in Repeater.ItemTemplate that has a custom control

Title is a bit of a mouthful, but I'm a bit stuck on this issue.
I have a search result page with has a custom control that has a Repeater. The ItemTemplate in the repeater is a PlaceHolder so I can construct the Item in a particular format; more specifically, I have a string of 'diseases' that come in the form of Disease1|disease2|disease3 and need to be given links for each disease.
Now for some code:
The following is the SearchResultControl.ascx
<asp:Panel ID="SearchResultPanel" runat="server" ScrollBars="Auto">
<asp:Repeater ID="Repeater1" runat="server"
onitemcreated="Repeater1_ItemCreated"
onitemcommand="Repeater1_ItemCommand">
<ItemTemplate>
<asp:PlaceHolder ID="ItemTemplatePlaceHolder" runat="server">
</asp:PlaceHolder>
</ItemTemplate>
<SeparatorTemplate>
<tr>
<td colspan="6"><hr /></td>
</tr>
</SeparatorTemplate>
</asp:Repeater>
</asp:Panel>
The code behind: SearchResultControl.ascx.cs
protected void Repeater1_ItemCreated(object sender, RepeaterItemEventArgs e)
{
if (e.Item.DataItem != null)
{
PlaceHolder placeHolder = e.Item.FindControl("ItemTemplatePlaceHolder") as PlaceHolder;
Control searchResultItem = Page.LoadControl("SearchResultItem.ascx");
DataRow row = (e.Item.DataItem as DataRowView).Row;
if (row != null)
{
string diseaseState = row["DiseaseStates"] as string;
searchResultItem.GetType().GetProperty("DiseaseStates").SetValue(searchResultItem, diseaseState, null);
placeHolder.Controls.Add(searchResultItem);
}
}
}
(Full disclosure, I got this idea from this question)
The SetValue calls the DiseaseStates property in SearchResultItem which in turn calls the following method to build the links, set the text, and the events:
private void BuildDiseaseStateLabels(string diseaseStates)
{
PlaceHolder placeHolder = FindControl("DiseaseStatePlaceHolder") as PlaceHolder;
string[] diseaseStateSplit = diseaseStates.Split(new char[] { '|' }, StringSplitOptions.RemoveEmptyEntries);
int count = diseaseStateSplit.Length;
foreach (string diseaseState in diseaseStateSplit)
{
LinkButton diseaseStateLink = new LinkButton();
diseaseStateLink.Text = diseaseState;
//diseaseStateLink.Click += new EventHandler(OnDiseaseStateLinkClick);
diseaseStateLink.CommandArgument = "<%# Eval(\"PatientID\")+ \";\" + Eval(\"PatientStatus\")+ \";\" + Eval(\"Age\")+ \";\" + Eval(\"DiseaseStates\")%>";
diseaseStateLink.CommandName = "OnDiseaseStateLinkClick";
//diseaseStateLink.Command += new CommandEventHandler(OnDiseaseStateLinkClick);
placeHolder.Controls.Add(diseaseStateLink);
if (count != 0)
{
Label splitLabel = new Label();
splitLabel.Text = "|";
placeHolder.Controls.Add(splitLabel);
}
}
}
This is the layout for the SearchResultItem
<div id="SearchResultItemDiv" class="MainSearchResultItem">
<asp:PlaceHolder ID="DiseaseStatePlaceHolder" runat="server">
</asp:PlaceHolder>
</div>
Initially I tried setting the Click event, but that doesn't work at all. I then set the CommandArgument and CommandName but that didn't seem to do the trick. I figured the Command event might need to be set, but again, no luck. I should note that when a link is clicked the Repeater1_ItemCreated in SearchResultControl.ascx.cs is called. But since there is no data in e.Item.DataItem is null and I lose the results.
In one of the questions regarding the same issue, it was suggested that the OnItemCommand be added, but even that doesn't get called.
I also read A Stumper of an ASP.NET Question and A Stumper of an ASP.NET Question: SOLVED!, to no avail.
What could I possibly be doing wrong? All of the correct event hookups seem there, I'm checking for IsPostBack and not doing DataBind() again. blaaargharaggh
Help is always greatly appreciate.

I believe you're running into this issue because the LinkButton controls are recreated too late in the page lifecycle. You have to remember that when the page is posted back, the control technically does not exist anymore, so the event handler cannot be fired.
If you can recreate the LinkButton controls somewhere before the Page_Load event is reached, like OnInit for example, everything should work fine.
For simple pages the above usually works very well, but there are circumstances where recreating controls during OnInit requires a lot of overhead, such as storing counters or arrays in ViewState so you can keep track of the controls that need to be recreated after postback. In these situations I would suggest taking a look at the DynamicControlsPlaceHolder by Denis Bauer. This control is capable of persisting dynamic controls without any addtional code required, which is pretty awesome.
Here's a link to the latest version:
http://www.denisbauer.com/ASPNETControls/DynamicControlsPlaceholder.aspx

The problem might be that you're not doing the DataBind() again.
Because you're building the buttons on the fly, when the page post backs, the buttons haven't been created and are unable to work out which click event it should be firing.
Try getting rid of the IsPostBack check, so each time the page loads, you're re-build the repeater.

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);
}
}