Asp.net Core – Centralising FluentValidation rules to a service

This is quite an easy thing to do, might not be work blogging, but hey – might save you few minutes in the future.

This is ho your AbstractValidator looks like.

public class CommandValidator : AbstractValidator<Command>
        {
            public CommandValidator(IFieldValidatorService validatorService)
            {
                RuleFor(x => x.Name).NotNull().NotEmpty();
                RuleFor(x => x.StartDate).NotNull().NotEmpty().Must(validatorService.ValidDate).WithMessage(ValidationMessages.Project.StartDate);
                RuleFor(x => x.StartDate).Must(validatorService.GreaterThanToday).WithMessage(ValidationMessages.Project.StartDateGreaterThanToday);
                RuleFor(x => x.EndDate).NotNull().NotEmpty().Must(validatorService.ValidDate).WithMessage(ValidationMessages.Project.EndDate);
                RuleFor(x => x.Image).Must(validatorService.ValidProjectImageAllowedFileType).WithMessage(ValidationMessages.Project.Image);
            }            
        }

This is the service implementation

    public class FieldValidatorService : IFieldValidatorService
    {
        public bool ValidDate(DateTime date)
        {
            return !date.Equals(default(DateTime));
        }

        public bool GreaterThanToday(DateTime date)
        {
            if(date > DateTime.UtcNow)
                return true;

            return false;
        }

        public bool ValidProjectImageAllowedFileType(PostedFile image)
        {
            string[] allowedFileTypes = { ".jpg", ".png" };

            if (image == null)
                return true;

            if (string.IsNullOrWhiteSpace(image.FileName))
                return false;

            if (!allowedFileTypes.Contains(Path.GetExtension(image.FileName)))
                return false;

            return true;
        }
    }