Introducing Spaanjaars.Validation.SharedAttributes

Last week Scott Brady sent me the code for a number of attributes compatible with the validation framework I use in my article series on N-Layer design.

Rather than posting the code "as is" as a text file on my server, I decided to create (and share) a little Visual Studio solution for it that hosts the source for the attributes in VB.NET and in C#. The Visual Studio solution that you can download at the end of this article contains two class libraries with attributes: one in VB.NET and one in C#. Feel free to download the code and make any modifications you see fit.

The original source was in VB only, but I used Telerik's great on-line source converter to quickly create C# versions of the attributes, except for one. I didn't have the time to fix the many compile errors in the ValidCreditCardNumberAttribute class, so it's not included in the C# version. The current solution includes the following attributes:

Attribute name Description VB  C#  Contributed by
ExactLengthAttribute Validates the exact length of a string. Yes Yes Scott Brady
MaxLengthAttribute Validates the maximum length of a string. Yes Yes Scott Brady
MinLengthAttribute Validates the minimum length of a string. Yes Yes Scott Brady
RegularExpressionAttribute Validates a string using a regular expression. Yes Yes Scott Brady
ValidCreditCardNumberAttribute Validates a credit card number. Yes  No Scott Brady

If you feel like contributing to this little project, or have comments, remarks, bug fixes or questions about the ones that are currently available, please send me a message. Also, if you have a working C# version of the ValidCreditCardNumberAttribute class and you're willing to share it, you can send me the code,

My idea is to keep an up-to-date list of the attributes here, combined with the full source code for them. Once I receive new contributions, I'll add them to the download and update this article


Visual Studio 2008 solution with attributes in C# and VB.NET

Where to Next?

Wonder where to go next? You can read existing comments below or you can post a comment yourself on this article .

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On Saturday, June 13, 2009 5:00:14 PM kurt schroeder said:
What i still amazing to me is the ease with which these can be added and changed.
On Wednesday, September 30, 2015 5:00:53 PM Willie said:
Could you assist me with condition validation? I wanted to make the field required base on other field entered value.

    public sealed class RequiredIfAttribute : ValidationAttribute
        public object objInstance;
        public string DependentProperty { get; set; }
        public object TargetValue { get; set; }

        public RequiredIfAttribute(string dependentProperty, object targetValue)
            this.DependentProperty = dependentProperty;
            this.TargetValue       = targetValue;

        public override bool IsValid(object value)
            PropertyInfo fieldPropertyInfo = objInstance.GetType().GetProperty(DependentProperty);
            if (fieldPropertyInfo != null)
                object val = fieldPropertyInfo.GetValue(objInstance, null);
                if (val != null)
                    if (val.ToString() == TargetValue.ToString())
                        return false;
            return true;
On Friday, October 02, 2015 9:29:38 PM Imar Spaanjaars said:
Hi Willie,

And the question is what, exactly?


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