Fluent validation - group two validators in one custom validator

Question

I have the following validator class:

public class FranchiseInfoValidator : AbstractValidator<FranchiseInfo>
    {
        public FranchiseInfoValidator()
        {
            RuleFor(franchiseInfo => franchiseInfo.FolderName).NotEmpty().Matches("^[a-zA-Z0-9_.:-]+$").WithMessage("Invalid characters");
            RuleFor(franchiseInfo => franchiseInfo.ExeIconName).NotEmpty().Matches("^[a-zA-Z0-9_.:-]+$").WithMessage("Invalid characters");
            RuleFor(franchiseInfo => franchiseInfo.FullName).NotEmpty().Matches("^[a-zA-Z0-9_.:-]+$").WithMessage("Invalid characters");
            RuleFor(franchiseInfo => franchiseInfo.ShortName).NotEmpty().Matches("^[a-zA-Z0-9_.:-]+$").WithMessage("Invalid characters");        
    }

NotEmpty() and Matches("^[a-zA-Z0-9_.:-]+$").WithMessage("Invalid characters") validators with the custom message are the same for all properties. Is it possible to group them in one custom validator and then write something like this:

RuleFor(franchiseInfo => franchiseInfo.FolderName).SetValidator(new CustomValidator());

I have done some custom validators but not in this scenario. Is this possible? I have found no such example in the documentation. Furthermore, I wonder if this is possible to be done generic so if I have another validator class with properties to apply the same custom validator? Thanks.

Answer 1

yes, it should work with something like that

public class MyCustomValidator : PropertyValidator
    {

        public MyCustomValidator()
            : base("Property {PropertyName} has invalid characters.")
        {
        }

        protected override bool IsValid(PropertyValidatorContext context)
        {
            var element = context.PropertyValue  as string;
            return !string.IsNullOrEmpty(element) && Regex.IsMatch(element, "^[a-zA-Z0-9_.:-]+$");
        }
    }

usage : with your code, or create your own extension

public static class MyValidatorExtensions {
   public static IRuleBuilderOptions<T, string> CheckIfNullAndMatches<T>(this IRuleBuilder<T, string> ruleBuilder) {
      return ruleBuilder.SetValidator(new MyCustomValidator<TElement>());
   }
}

then usage would be

RuleFor(franchiseInfo => franchiseInfo.FolderName).CheckIfNullAndMatches();

You could also have a regex as a parameter, if you need a more generic validator...

doc here