Labels

Friday, April 6, 2007

Hide Error Label on Body On-Load.

Below is to show how the Labels are used to show errors.

 

Declaratively we make the Label as Visible. Otherwise it won’t be accessible thru Javascript.

 

<asp:Label ID="Label1" runat="server" Text="Error Label" ForeColor="Red" Visible="true"></asp:Label>

 

But at first time the Page loads, we definitely would not like to show the error label. Hence we will make it invisible thru JavaScript using below.

 

<script language="javascript">   

        window.onload=function() {HideMe();}       

</script>

 

Now when first time the Page Loads below happens:

þ      Page_Load

þ      Page_PreRender

þ      body_onload_clientside : This hides Label again by calling above script.

þ      Page_Render

þ      Page_Unload

 

Now let’s say we have a button having an attached JS call. If JS script return true we need to call Server Side otherwise Error label should become visible,

<asp:Button ID="Outer" runat="server" OnClick="Button1_Click" OnClientClick=" return Validate();" Text="Outer" />

Below sequence fires.

  • When the button is clicked below event happens:
    • button_clientside_click :
      • If return false then the Error label will become visible and no server side event will occur.
      • If return true, then the flow will be redirected to server and below event happens.
        • Page_Load: Label gets Visible here using the declarative values.
        • Button_ServerSide_Click : Sleeps thread for 2 secs.
        • Page_PreRender
        • body_onload_clientside : This hides Label again by calling 'window.onload="Hide();'
        • Page_Render : Label gets In-Visible.
        • Page_Unload

// ------------------------------------------------
function Hide()
{
document.getElementById('Label1').style.display='none';
}

function UnHide()
{
document.getElementById('Label1').style.display='block';
}

 

function Validate()

        {

            var response=CheckValidation();

            if(response)

            {

                return true;

            }

            else

            {

                UnHide();

                return false.

            }           

        }

// ------------------------------------------------

Hope it is Clear.

 

 

Thanks & Regards,

Arun Manglick

SMTS || Microsoft Technology Practice - Bridgestone - Tyre Link || Persistent Systems

 

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