Cause a PostBack on KeyPress from the asp.net dropdownlist

I recently bumped into a solution given by Vince Xu where he suggested a technique of causing a postback from a dropdownlist on any keypress. If you desire, you can easily filter the key code and cause postback on specific keypress. This technique can be useful when you plan to Implementing KeyBoard Shortcuts in ASP.NET applications 

Here’s how to cause a postback from DropDownList on keypress

C#

protected void Page_Load(object sender, EventArgs e)
{
if (Request.Params["__EVENTTARGET"] != null)
{
string evnt = Request.Params["__EVENTTARGET"].ToString();
string args = Request.Params["__EVENTARGUMENT"].ToString();
if (evnt == "DropDownList1" && args == "onkeypress")
{
    // write some code to execute on postback
}
}

DropDownList1.Attributes.Add("onkeypress", 
Page.GetPostBackEventReference(DropDownList1,"onkeypress"));
}

VB.NET

Protected Sub Page_Load(ByVal sender As Object, _
                        ByVal e As EventArgs)
    If Request.Params("__EVENTTARGET") IsNot Nothing Then
        Dim evnt As String = _
        Request.Params("__EVENTTARGET").ToString()
        Dim args As String = _
        Request.Params("__EVENTARGUMENT").ToString()
        If evnt = "DropDownList1" _
                   AndAlso args = "onkeypress" Then
            ' write some code to execute on postback
        End If
    End If

DropDownList1.Attributes.Add("onkeypress",_
Page.GetPostBackEventReference(DropDownList1, "onkeypress"))
End Sub

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About The Author

Suprotim Agarwal, ASP.NET Architecture MVP works as an Architect Consultant and provides consultancy on how to design and develop Web applications.

Suprotim is also the founder and primary contributor to DevCurry, DotNetCurry and SQLServerCurry. He has also written an EBook 51 Recipes using jQuery with ASP.NET Controls.

Follow him on twitter @suprotimagarwal