User input is overridden by page_load during cross page postback

Question

1the source page has a page load method like below:

protected void Page_Load(object sender, EventArgs e)
        {
                TextBox1.Text = DateTime.Today.AddDays(1).ToShortDateString();
        }

it will result a textbox1.text to display tomorrow's date when the source page is rendered. I have this source page cross post back to a target page, and in the target page load event i have

if (Page.PreviousPage != null && PreviousPage.IsCrossPagePostBack == true)
            {
              TextBox SourceTextBox1 = (TextBox)Page.PreviousPage.FindControl("TextBox1");
                if (SourceTextBox1 != null)
                {
                    Label1.Text = SourceTextBox1.Text;
                 }
              }

the problem is if the user changes the content of textbox1, supposely, the label1 on target page should catch the user input and display it, but now it only displays whatever i set in the source page load event. I understand the self page post back life cycle, but this is cross page post back. IMO, the source page load event has nothing to do with this, but why it overrides the user input?? Any idea.

score 1 · Accepted Answer · answered Mar 12 '13 at 15:42

1

Just surround this with a if(!IsPostBack) check:

protected void Page_Load(object sender, EventArgs e)
{
    if(!IsPostBack)
    {
        TextBox1.Text = DateTime.Today.AddDays(1).ToShortDateString();
    }
}

Otherwise the value will be overwritten on every postback. So when you Server.Transfer it to the other page it is already changed.

answered Mar 12 '13 at 15:42

Tim Schmelter

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Thanks Tim. It works..I am just wondering at which phase the server.transfer or cross page post back happens? it looks like when the cross page post back button hit, the source page goes through a normal page life cycle like self post back, and server.transfer just happens after the page_load event? – John Mar 12 '13 at 15:49
@John: the target page is invoked using an HTTP POST command, which sends the values of controls on the source page to the target page. So yes, first the source page is loaded and then the target page is onvoked which replaces the source. – Tim Schmelter Mar 12 '13 at 15:54

User input is overridden by page_load during cross page postback

1 Answers1