ASP.NET : Check for click event in page_load

Question

In c#, how can I check to see if a link button has been clicked in the page load method?

I need to know if it was clicked before the click event is fired.

If your code is reliant on the OnClick event, then you can put that particular code in the OnPageRender override (rather than in Page_Load), as it will fire after the OnClick event handler. — snumpy, Aug 12 '15 at 13:32

score 25 · Accepted Answer · answered Oct 09 '08 at 18:35

25

if( IsPostBack ) 
{
    // get the target of the post-back, will be the name of the control
    // that issued the post-back
    string eTarget = Request.Params["__EVENTTARGET"].ToString();
}

answered Oct 09 '08 at 18:35

Jared

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Did you test this? Should have two leading slashes - "__EVENTTARGET" – Tsvetomir Tsonev Oct 09 '08 at 18:39
Any ideas how this can be used with an Update Panel? It doesn't seem to work – Thomas Feb 09 '11 at 20:51

score 4 · Answer 2 · answered Jan 28 '15 at 04:07

4

if that doesn't work.Try UseSubmitBehavior="false"

answered Jan 28 '15 at 04:07

RealSteel

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tvanfosson · Answer 3 · 2008-10-09T20:14:35.423

2

Check the value of the request parameter __EVENTTARGET to see if it is the id of the link button in question.

edited Oct 09 '08 at 20:14

answered Oct 09 '08 at 18:35

tvanfosson

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score 2 · Answer 4 · answered Oct 09 '08 at 18:36

2

The UniqueID of the button will be in Request.Form["__EVENTTARGET"]

answered Oct 09 '08 at 18:36

Tsvetomir Tsonev

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score 1 · Answer 5 · answered Dec 04 '15 at 17:35

Based on accepted answer and the answer of RealSteel this could be a more complete answer.

First add to the .aspx a button like this:

<asp:Button id="btnExport" runat="server" Text="Export" UseSubmitBehavior="false"/>

Then on the Page_Load method:

if(IsPostBack){
   var eventTarget = Request.Params["__EVENTTARGET"]
   // Then check for the id but keep in mind that the name could be 
   // something like ctl00$ContainerName$btnExport 
   // if the button was clicked or null so take precautions against null
   // ... so it could be something like this
   var buttonClicked = eventTarget.Substring(eventTarget.LastIndexOf("$") + 1).Equals("btnExport")

}

score 0 · Answer 6 · answered Apr 20 '17 at 00:19

I just got the same trouble, have to do some logic judgement in the Page_Load method to treat different event(which button was clicked).

I realize the arm to get the as the following example.

The front end aspx source code(I have many Buttons with IDs F2, F3, F6, F12.

   <Button Style="display: none" ID="F2" runat="server" Text="F2:Cancel" OnClientClick="SeiGyo(this)" OnClick="F2_Click" />
    <Button Style="display: none" ID="F3" runat="server" Text="F3:Return" OnClientClick="SeiGyo(this)" OnClick="F3_Click" />
    <Button Style="display: none" ID="F6" runat="server" Text="F6:Run" OnClientClick="SeiGyo(this)" OnClick="F6_Click" />
    <Button Style="display: none" ID="F12" runat="server" Text="F12:Finish" OnClientClick="SeiGyo(this)" OnClick="F12_Click" />

The back end aspx.cs source code, what I need to do is judge which button was clicked when Page_Load was triggered. It seems a little stupid, but works. I hope that will be helpful to some others

Dictionary<string, string> dic = new Dictionary<string, string>();
foreach(var id in new string[]{"F2","F3","F6","F12"})
{
       foreach (var key in Request.Params.AllKeys)
                    {
                        if (key != null && key.ToString().Contains(id))
                            dic.Add(id, Request[key.ToString()].ToString()); 
                    }
}

ASP.NET : Check for click event in page_load

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