Custom Validation Control for Zip,Phone and Email
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Apr 17, 2007
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This article shows how to develop a custom validation control to validate zip,phone,email in one control.
Introduction
This article provides the readers code on how to create a custom validator control that does zip,phone and email validation all in one, by specifying a property. Thought of sharing it with other code project readers to get feedback and also provide users with a ready control.
Background
While working on a project for one of my clients, I had to create a standard form with zip,phone, email and other contact information. I had to validate the zip,email and phone for blanks and regular expressions. I started out by creating 2 controls a required field validator and regular expression validator, though the validation worked fine, the rendering was bad especially when checking for the regular expression it would show a blank and then the message, the blank being the reqd field validator.
The client was against my using javascript and so inorder to remove the gap and have only one validator control that does both i created a custom validator control and that got me what i wanted.
Using the code
In order to create a custom control, you would start with creating a class file, in this example it would be CustomZipValidator.vb and place it in the app code folder. The code in the class file is shown below, this class would inherit from the BaseValidator class and would override the EvaluateIsValid() method.
'Inherits the base validator Public Class CustomZipPhoneEmailValidator Inherits BaseValidator 'Override the EvaluateIsValid Protected Overrides Function EvaluateIsValid() As Boolean Dim value As String = Me.GetControlValidationValue(Me.ControlToValidate) If (value.Equals(String.Empty) Or value.Length = 0) Then Return False Else If _propertyToValidate.Equals("Zip") Then If Regex.IsMatch(value, "(^(?!0{5})(\d{5})(?!-?0{4})(-?\d{4})?$)") = False Then ErrorMessage = "Invalid Postal Code format,Please try xxxxx or xxxxx-xxxx" Return False Else Return True End If End If If _propertyToValidate.Equals("Phone") Then If Regex.IsMatch(value, "((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}") = False Then ErrorMessage = "Invalid Phone format,Please try (xxx)xxx-xxxx or xxx-xxx-xx" Return False Else Return True End If End If If _propertyToValidate.Equals("Email") Then If Regex.IsMatch(value, "\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*") = False Then ErrorMessage = "Not a valid email" Return False Else Return True End If End If End If End Function
Points of Interest
Coming from a background of backend business layer programming, the custom validators of ASP.NET2.0 saved my day.