set errormessage for customvalidator?

I would like to use a customvalidator control to handle all my validation, but I can't figure out how to set the error message in the co开发者_如何学编程de-behind for different checks. Is this possible?

You can set the error message in the OnServerValidate method as you wish based on your validation logic:

protected void customValidator1_Validate(object sender, ServerValidateEventArgs e)
{
    if (e.Value.Length < 5)
    {
        e.IsValid = true;
    }
    else
    {
        customValidator1.ErrorMessage = "Length must be less than 5.";
        e.IsValid = false;
    }
}

For One Control you can do like this..

<!-- In Designer Page  -->
<asp:CustomValidator runat="server" id="cusCustom" controltovalidate="txtCustom" 
  onservervalidate="cusCustom_ServerValidate" 
  errormessage="The text must be exactly 8 characters long!" />
<br /><br />

/* In Code Behind*/
protected void cusCustom_ServerValidate(object sender, ServerValidateEventArgs e)
{
    if(e.Value.Length == 8)
        e.IsValid = true;
    else
        e.IsValid = false;
}