Validation Attribute localization

Question

I'm working on a ASP .Net Core 5 project, where I created a custom Validation Attribute and in case when the validation result is not valid I want to return a localized error message.

Here is the ViewModel with the validation attribute:

  public class MyViewModel()
  {
    [Required(ErrorMessage = "RequiredMsg")]
    [CheckTextIsValid(new char[] { 'a', 'b', 'c' }, ErrorMessage = "NotAllowedChars")]
    public string Name { get; set; }

    [Required(ErrorMessage = "RequiredMsg")]
    [CheckTextIsValid(new char[] { 'a', 'b', 'c' }, ErrorMessage = "NotAllowedChars")]
    public string SureName { get; set; }

    [Required(ErrorMessage = "RequiredMsg")]
    [CheckTextIsValid(new char[] { 'a', 'b', 'c' }, ErrorMessage = "NotAllowedChars")]
    public string Address { get; set; }

    [Required(ErrorMessage = "RequiredMsg")]
    public string Phone { get; set; }

    [Required(ErrorMessage = "RequiredMsg")]
    [CheckTextIsValid(new char[] { 'a', 'b', 'c' }, ErrorMessage = "NotAllowedChars")]
    public string Country { get; set; }
  }

The "RequiredMsg" is localized and it works, so when there's error I can see the value of "RequiredMsg" = "This feild is required". But it's not working for "NotAllowedChars".

Here is CheckTextIsValid validation code:

public class CheckTextIsValid :ValidationAttribute
    {
        private char[] NotAllowedChars { get; set; }

        public CheckTextIsValidForSdi(char[] notAllowedChars)
        {
            NotAllowedChars = notAllowedChars;
        }
        public override bool IsValid(object value)
        {
            ..... Logic..
            if(//IsValid)
            {
                return ValidationResult.Success;
            }else{
               return new ValidationResult( string.Format(ErrorMessage, notAllowedChars)); // Here the ErrorMessage is "NotAllowedChars"
            }

        }
    }

How can I read the value of "NotAllowedChars" from the resources?

I know that there's a lot of questions about this: (

ASP.NET Core custom validation attribute localization,

ErrorMessageTranslationService, This is work perfectly with IHtmlLocalizer. ButI need to IHtmlLocalizer<T> because I'm gonna use CheckTextIsValid() in different View Models and pass different error messages.

), but still I couldn't fix this problem.

score 0 · Answer 1 · answered Feb 08 '22 at 06:08

I write a simply demo to show custom validation

Model

public class MyViewModel
    {
        [Required(ErrorMessage = "RequiredMsg")]
        [CheckTextIsValid(new char[] { 'a', 'b', 'c' }, ErrorMessage = "Name can't contain a,b,c")]
        public string? Name { get; set; }

        [Required(ErrorMessage = "RequiredMsg")]
        [CheckTextIsValid(new char[] { 'a', 'b', 'c' }, ErrorMessage = "Password can't contain a,b,c")]
        public string? Password { get; set; }
    }

validation

public class CheckTextIsValid : ValidationAttribute
    {
        private char[] NotAllowedChars { get; set; }

        public CheckTextIsValid(char[] notAllowedChars)
        {
            NotAllowedChars = notAllowedChars;

        }
        protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
        {
            var v = (string)value;
            var result = v.IndexOfAny(NotAllowedChars);
            if (result == -1)
            {
                return ValidationResult.Success;
            }

            return new ValidationResult(ErrorMessage);

        }
    }

Then you can see When I input NewYork and a, The ErrorMessage will display behind a.

Notice: This demo just custom server-side validation, if you want custom client-side validation you can refer to this link.

Validation Attribute localization

1 Answers1