How to handle validation when JavaScript is disabled in ASP.NET
Question
I'm using some of the typical ASP.NET's Validation Controls in my website. Now I'm trying to disable the JavaScript in my browser to test my application and of course the Validation Controls no longer works. I think it's best to try to make them work using one of the suggested solutions down here instead of reinvesting the wheel and build a validation layer for the page or my objects -Am I thinking right?-
What do you think of these options and why:
Include in clicked button's event a code to check if the page is valid and if not explicitly call the
Page.Validate();methodCheck if whether the JavaScript is enabled and if not I should call
Page.Validate();
If you there's a better way to do it please let me know.
3 answers
solution1
3 2011-04-04 03:41:48
Javascript form validation is purely for user convenience. This stops them from submitting a form with an invalid phone number or whatever.
All inputs should actually be validated on the server when whatever request is being made is received. Here's the ideal flow, and you'll see that a browser not having javascript enabled is no big deal:
browser -> javascript validation (optional) -> server validation (if this fails, go back to initial page with errors)
So even if they have no JS, the page still submits the data, then you can return an error from the server. This is a poorer user experience typically (full page reload, potential retyping of inputs unless you repopulate the forms) which is why JS is often included in validation schemes.
solution2
1 ACCPTED 2011-04-04 03:41:24
The validation controls are designed to validate primarily on the server side. The client-side validation is optional (see the EnableClientScript property). So if they aren't working with Javascript disabled, then you're probably missing a little boilerplate code in your page, such as this snippet from the MSDN documentation on Page.IsValid :
private void ValidateBtn_Click(Object Sender, EventArgs E)
{
Page.Validate();
if (Page.IsValid == true) // yes, it is written this way in the MSDN documentation
lblOutput.Text = "Page is Valid!";
else
lblOutput.Text = "Some required fields are empty.";
}
You can also call Page.Validate and check Page.IsValid in your Page's OnLoad event, so that you can prevent a postback from proceeding to the next step when the form needs to be re-submitted. You probably don't even need to call Validate() explicitly — Button.CausesValidation is true by default.
solution3
0 2011-04-04 04:15:24
You will need to do custom Server Side validation... http://msdn.microsoft.com/en-us/library/aa479013.aspx (information toward the bottom)
Something like this:
<%@ Page Language="C#" %>
<script runat="server">
void Button1_Click(Object sender, EventArgs e) {
if (Page.IsValid) {
Label1.Text = "VALID ENTRY!";
}
}
void ValidateNumber(object source, ServerValidateEventArgs args)
{
try
{
int num = int.Parse(args.Value);
args.IsValid = ((num%5) == 0);
}
catch(Exception ex)
{
args.IsValid = false;
}
}
</script>
<html>
<head>
</head>
<body>
<form runat="server">
<p>
Number:
<asp:TextBox id="TextBox1"
runat="server"></asp:TextBox>
<asp:CustomValidator id="CustomValidator1"
runat="server" ControlToValidate="TextBox1"
ErrorMessage="Number must be even"
OnServerValidate="ValidateNumber"></asp:CustomValidator>
</p>
<p>
<asp:Button id="Button1" onclick="Button1_Click"
runat="server" Text="Button"></asp:Button>
</p>
<p>
<asp:Label id="Label1" runat="server"></asp:Label>
</p>
</form>
</body>
</html>
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