CustomValidator
Regular Expressions in JavaScript4
another great article, this time on the use of regular expressions with JavaScript
Table 6.2. Common regular expression components and their descriptions
Special |
Description |
Character |
|
. |
any character |
^ |
beginning of string |
$ |
end of string |
\d |
numeric digit |
\s |
whitespace character |
\S |
non-whitespace character |
(abc) |
the string abc as a group of characters |
? |
preceding character or group is optional |
+ |
one or more of the preceding character or group |
* |
zero or more of the preceding character or group |
{n} |
exactly n of the preceding character or group |
{n,m} |
n to m of the preceding character or group |
(a|b) |
either a or b |
\$ |
a dollar sign (as opposed to the end of a string); we can ‘escape’ |
|
any of the special characters listed above by preceding it with |
|
a backslash. For example, \. matches a period character, \? |
|
matches a question mark, and so on |
You’ll find a complete guide and reference to regular expressions and their components in the .NET Framework SDK Documentation.
CustomValidator
The validation controls included with ASP.NET allow you to handle many kinds of validation, yet certain types of validation cannot be performed with these built-in controls. For instance, imagine that you needed to ensure that a new
4 http://www.sitepoint.com/article/expressions-javascript
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Chapter 6: Using the Validation Controls
user’s login details were unique by checking them against a list of existing usernames on the server. The CustomValidator control can be helpful in this situation, and others like it. Let’s see how:
Visual Basic File: CustomValidator.aspx (excerpt)
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>CustomValidator Control Sample</title> <script runat="server" language="VB">
Sub CheckUniqueUserName(s As Object, _ e As ServerValidateEventArgs)
Dim username As String = e.Value.ToLower
If (username = "zak" Or username = "cristian") Then e.IsValid = False
End If End Sub
Sub submitButton_Click(s As Object, e As EventArgs) If Page.IsValid Then
submitButton.Text = "Valid" Else
submitButton.Text = "Invalid!" End If
End Sub </script>
</head>
<body>
<form runat="server"> <p>
New Username:<br />
<asp:TextBox ID="usernameTextBox" runat="server" /> <asp:CustomValidator ID="usernameUnique" runat="server"
ControlToValidate="usernameTextBox"
OnServerValidate="CheckUniqueUserName" ErrorMessage="This username already taken!" />
</p>
<p>
<asp:Button ID="submitButton" runat="server" OnClick="submitButton_Click" Text="Submit" />
</p>
</form>
</body>
</html>
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CustomValidator
C# |
File: CustomValidator.aspx (excerpt) |
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>CustomValidator Control Sample</title> <script runat="server" language="C#">
void CheckUniqueUserName(Object s, ServerValidateEventArgs e)
{
string username = e.Value.ToLower(); if(username == "zak" || username == "cristian")
{
e.IsValid = false;
}
}
void submitButton_Click(Object s, EventArgs e)
{
if(Page.IsValid)
{
submitButton.Text = "Valid";
}
else
{
submitButton.Text = "Invalid!";
}
}
</script>
</head>
<body>
<form runat="server"> <p>
New Username:<br />
<asp:TextBox ID="usernameTextBox" runat="server" /> <asp:CustomValidator ID="usernameUnique" runat="server"
ControlToValidate="usernameTextBox"
OnServerValidate="CheckUniqueUserName" ErrorMessage="This username already taken!" />
</p>
<p>
<asp:Button ID="submitButton" runat="server" OnClick="submitButton_Click" Text="Submit" />
</p>
</form>
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