Date Field Validation
In .NET, it is really easy to check whether a user is entering a date into a form field, although it’s not necessarily obvious how to do so. What you need to do is include a CompareValidator in your web form. The code would look like this:
<asp:TextBox ID="txtBirthDate" runat="server"></asp:TextBox> <asp:CompareValidator ID="CompareValidator1" runat="server" ErrorMessage="CompareValidator" ControlToValidate="txtBirthDate" Operator="DataTypeCheck" Type="Date"></asp:CompareValidator>
The three important properties that you need to set in the CompareValidator are:
- ControlToValidate - This is the ID of the Textbox
- Operator - Default is “Equal”, need to change to DataTypeCheck
- Type - Default is String, set to Date
This will cause the validator to return the error message when an invalid date is entered. It will accept dates such as “4/18/2004″, “9/12/95″ and “02/29/2004″, however would cause the error message to be displayed on “14/14/2000″, “02/29/2005″, and “January 1, 2000″. I’d like to see it accept the last one, however, the date should be in the format mm/dd/yyyy, be sure to tell the users to enter this format.
Of course, to be semantically correct, you’d want to give your Textbox a label on the form, and the CompareValidator a more descriptive error message. Also, be sure to enable server side validation, see “Server-Side Validation“.
This tip came from Peter Blum, on dnrTV. Peter has done a ton of work with validation in .NET. His product, Professional Validation and More looks very promising.
