Question

I have form data that I insert into a database when the user clicks on a submit button. The problem is that after the original submission if the user refreshes the page the form data will be resubmitted and thus inserted into the database a second time. How can I fix this?

Answer 1

Use an appropriate mechanism to detect double posting.
I prefer to use the following so as to detect whether the underlying request is doubled posted or not.

private bool refreshState;
private bool isDoublePosted;

protected bool IsInDoublePosting
{
    get 
    {
        return isDoublePosted;
    }
}

protected override void LoadViewState(object savedState)
{
    object[] states = (object[])savedState;
    base.LoadViewState(states[0]);
    refreshState = Convert.ToBoolean(states[1]);
    isDoublePosted = (refreshState == Convert.ToBoolean(Session["IsInDoublePosting"]));
}

protected override object SaveViewState()
{
    Session["IsInDoublePosting"] = refreshState;
    object[] states = new object[3];
    states[0] = base.SaveViewState();
    states[1] = !refreshState;
    return states;
}

In your button click event handler:

    if (!this.IsInDoublePosting)
    { 
        // your code goes here
    }