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Avoid inserting twice when user refresh page in ASP.NET

, 28 Aug 2011
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Avoid inserting twice when user refresh page in ASP.NET
Hi all,
 
This is something that I have done to avoid insertion of records into database twice when user presses refresh. It is so simple. I am just using session and view state, and comparing the dates stored in them.
 
Here is the code:
 
'Storing the now date in session variable on page load:
Sub Page_Load (sender As Object, e As EventArgs)
    If Not Page.IsPostBack
        Session("update") = Server.URLEncode(System.DateTime.Now.ToString())
    End If
End Sub
 
'Storing the date also in view state on page prerender :\
Sub Page_PreRender (sender As Object, e As EventArgs)
    ViewState("update") = Session("update")
End Sub
 

Finally check if the dates are equal, so if yes we insert and update the session value to the date of insertion, thus the view state value and session value will not be equal in the next postback. Here is the code :

 
Sub Button1_Click(sender As Object, e As EventArgs)
    If Session("update").ToString() = ViewState("update").ToString() Then
        If AddEmployee(firstName.Text, lastName.Text) = 0
            Message.Text = "Success"
            Session("update") = Server.URLEncode(System.DateTime.Now.ToString())
        Else
            Message.Text = "Failure"
        End If
    Else
        Message.Text = "Failure - Session"
    End If
    firstName.Text = ""
    lastName.Text = ""
End Sub
 
Hope that you like it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

mhamad zarif
Software Developer Netiks
Lebanon Lebanon
I have been a programmer for about one year.My power is in asp.net and flash (actionscript 3).I also work on windows application using vb.net and c#.

Comments and Discussions

 
GeneralRe: why would i want to learn vb.net - especially when it has su... Pinmemberguylwalker30-Aug-11 16:54 
GeneralRe: doh, i should have known that! it's been forever since i di... Pinmemberguylwalker30-Aug-11 16:50 
Generalvery nice article // Pinmemberdineshkummarc17-Nov-11 23:43 
GeneralYou are using an assignment operator (=) in your two If stat... Pinmemberguylwalker29-Aug-11 12:21 
GeneralRe: In VB.NET, (=) is the comparison operator and the assignment... PinprotectorAspDotNetDev29-Aug-11 13:14 
GeneralRe: hey man.This is vb.net and not c#.In vb.net we use only sing... Pinmembermhamad zarif29-Aug-11 22:26 
GeneralReason for my vote of 3 Netural. Just wondering why Server.U... PinmemberNikhil Mittal29-Aug-11 1:44 
GeneralI don't think Server.URLEncode really required here? PinmemberVenkatesh Mookkan28-Aug-11 18:08 

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