CODEWITHSUNDEEP
c#asp.net
Dylan
Dylan

Reputation: 137

How to know the target control for postback in asp.net

First Page

<html >
<head >
</head>
<body>
<form id="form1" runat="server">

<asp:Button ID="btnSubmit" runat="server" 
            OnClick="btnSubmit_Click"            
            Text="Submit to Second Page" />
</div>
</form>
</body>

btnSubmit_Click Event

Response.redirect("Page2.aspx");

In the Page Load of Page2, how to find which button causes postback?

Upvotes: 0

Views: 1927

Answers (4)

Mehdi Bugnard
Mehdi Bugnard

Reputation: 3979

Do have try this solution ? here : On postback, how can I check which control cause postback in Page_Init event

public static string GetPostBackControlId(this Page page)
{
    if (!page.IsPostBack)
        return string.Empty;

    Control control = null;
    // first we will check the "__EVENTTARGET" because if post back made by the controls
    // which used "_doPostBack" function also available in Request.Form collection.
    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 and we need to
        // iterate over the form collection to find it

        // ReSharper disable TooWideLocalVariableScope
        string controlId;
        Control foundControl;
        // ReSharper restore TooWideLocalVariableScope

        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;
}

Upvotes: 0

Alexander
Alexander

Reputation: 2477

If you really need the information from which button the post came, you'd implement Cross-Page Posting. It's a good article with examples. I'd prefer that method over using a QueryString (which might be slightly faster to implement).

Upvotes: 0

RMalke
RMalke

Reputation: 4094

In the Page_Load, it is not possible to find which button caused the PostBack. In the Point-Of-View of Page 2, it is not even a Post. It is a completely new request. This is what Response.Redirect does, it indicates to the client browser to do a new Request.

If you really need to know, you can add a URL parameter, and get it as a Query String, as Pankaj Agarwal show is his answer.

EDIT after comment: Besides the Query String, you can use a Session like in the onClick:

Session["POST-CONTROL"] = "button2"

and in the Page_Load, you read it as:

var postControl = Session["POST-CONTROL"] != null ? Session["POST-CONTROL"].toString() : "";

Upvotes: 0

Pankaj Agarwal
Pankaj Agarwal

Reputation: 11309

on btnSubmit_Click event you can pass Query String Paramerter and in Page2 get query string Parameter.

Response.redirect("Page2.aspx?btnName=button1");

at Load Event of Page2.aspx page

protected void Page_Load(object sender, EventArgs e)
{
      string queryString = Request.QueryString["btnName"].ToString();
      //Here perform your action
}

Upvotes: 1

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