What is a good server side validation library for .net?

I am trying to find a validation library to validate user input on the server side

Basically, I would like to avoid the following code appearing 15-20 times per page :

If Not String.IsNullorEmpty(txtDate.text) Then
    StrMsg.appendline("Please enter Date")
ElseIf Not IsDate(txtDate.text) Then
    StrMsg.appendl开发者_如何转开发ine("Date must be numeric")
End If

I want to do something like this :

StrMsg.AppendLine(ValidateField(txtDate, SQLDataType.Date, Required))

Does anything like this exist?

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You can use built in Validation controls

User Input Validation

Validation controls

After you have configured validation controls, all you have to do is check

Page.IsValid