ASP.NET MVC - "Validation type names must be unique."

Question

I use ASP.NET MVC 3 and Data Annotations in my model, and want to retrieve the Error Messages from a database. So I wrote inherited attributes:

public class LocalizedRequiredAttribute : RequiredAttribute
{
    public LocalizedRequiredAttribute(){}

    public override string FormatErrorMessage(string name)
    {
        return GetByKeyHelper.GetByKey(this.ErrorMessage);
    }       
}

public class LocalizedRegularExpressionAttribute : RegularExpressionAttribute
{
    public LocalizedRegularExpressionAttribute(string pattern) : base(pattern){}

    public override string FormatErrorMessage(string name)
    {
        return GetByKeyHelper.GetByKey(this.ErrorMessage);
    }       
}

I wrote 2 "adapters" for these attributes to enable client validations, such as this:

public class LocalizedRequiredAttributeAdapter : DataAnnotationsModelValidator<LocalizedRequiredAttribute>
{
    public LocalizedRequiredAttributeAdapter(ModelMetadata metadata, ControllerContext context, LocalizedRequiredAttribute attribute)
        : base(metadata, context, attribute)
    {
    }

    public static void SelfRegister()
    {
        DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(LocalizedRequiredAttribute), typeof(RequiredAttributeAdapter));
    }

    public override IEnumerable<ModelClientValidationRule> GetClientValidationRules()
    {
        return new[] { new ModelClientValidationRequiredRule(ErrorMessage) };
    }
}

And in my global.asax I have these 2 lines:

        LocalizedRegularExpressionAttributeAdapter.SelfRegister();
        LocalizedRequiredAttributeAdapter.SelfRegister();

I get an exception "Validation type names in unobtrusive client validation rules must be unique. The following validation type was seen more than once: required" when my model renders the HTML for this property:

    [LocalizedRequired(ErrorMessage = "global_Required_AccountName")]
    [LocalizedRegularExpression(User.ADAccountMask, ErrorMessage = "global_Regex_AccountName")]        
    public string AccountName { get; set; }

What is wrong?

Jaco B Jaco B · Accepted Answer · 2015-10-06T19:12:49

I basically had the same problem and I managed to solve it with the following piece of code:

using System;
using System.Web.Mvc;

And the ValidationRule:

public class RequiredIfValidationRule : ModelClientValidationRule
{
    private const string Chars = "abcdefghijklmnopqrstuvwxyz";

    public RequiredIfValidationRule(string errorMessage, string reqVal,
        string otherProperties, string otherValues, int count)
    {
        var c = "";
        if (count > 0)
        {
            var p = 0;
            while (count / Math.Pow(Chars.Length, p) > Chars.Length)
                p++;

            while (p > 0)
            {
                var i = (int)(count / Math.Pow(Chars.Length, p));
                c += Chars[Math.Max(i, 1) - 1];
                count = count - (int)(i * Math.Pow(Chars.Length, p));
                p--;
            }
            var ip = Math.Max(Math.Min((count) % Chars.Length, Chars.Length - 1), 0);
            c += Chars[ip];
        }

        ErrorMessage = errorMessage;
        // The following line is where i used the unique part of the name
        //   that was generated above.
        ValidationType = "requiredif"+c;
        ValidationParameters.Add("reqval", reqVal);
        ValidationParameters.Add("others", otherProperties);
        ValidationParameters.Add("values", otherValues);
    }
}

I hope this helps.

ASP.NET MVC - "Validation type names must be unique."

3 Answers