在回发时，如何在 Page_Init 事件中检查哪个控件导致回发 [英] On postback, how can I check which control cause postback in Page_Init event

问题描述

在回发时，如何在 Page_Init 事件中检查哪个控件导致回发.

On postback, how can I check which control cause postback in Page_Init event.

protected void Page_Init(object sender, EventArgs e)
{
//need to check here which control cause postback?

}

谢谢

推荐答案

我看到已经有一些很好的建议和方法建议如何获得回发控制.但是我找到了另一个带有方法的网页(Mahesh blog)检索回发控制 ID.

I see that there is already some great advice and methods suggest for how to get the post back control. However I found another web page (Mahesh blog) with a method to retrieve post back control ID.

我会稍作修改，将其发布在这里，包括将其设为扩展类.希望它以这种方式更有用.

I will post it here with a little modification, including making it an extension class. Hopefully it is more useful in that way.

/// <summary>
/// Gets the ID of the post back control.
/// 
/// See: http://geekswithblogs.net/mahesh/archive/2006/06/27/83264.aspx
/// </summary>
/// <param name = "page">The page.</param>
/// <returns></returns>
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 IButtonControl)) continue;

            control = foundControl;
            break;
        }
    }

    return control == null ? String.Empty : control.ID;
}

更新 (2016-07-22): 类型检查 Button 和 ImageButton 更改为查找 IButtonControl 允许识别来自第三方控件的回发.

Update (2016-07-22): Type check for Button and ImageButton changed to look for IButtonControl to allow postbacks from third party controls to be recognized.

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