// Install LocalizedString.FluentValidation as a Cake Addin
#addin nuget:?package=LocalizedString.FluentValidation&version=1.0.1
// Install LocalizedString.FluentValidation as a Cake Tool
#tool nuget:?package=LocalizedString.FluentValidation&version=1.0.1

A helper library for FluentValidation that allows for easy declaration of error messages in various languages without the use of resource files. When ValidationResult is produced, the value of Thread.CurrentThread.CurrentCulture will be used to resolve the translations for the ErrorMessage fields.

Useful for short strings. If strings are getting longer -- consider switching to time-tested technique of using resource files.

The library uses LocalizedString, get more info here

Example:

class Student
    public string Name { get; set; }
    public double GPA { get; set; }
class StudentValidator : AbstractValidator<Student>
    public StudentValidator()
        RuleFor(x => x.Name).MinimumLength(3).WithMessage(
            "Name must be at least 3 characters long".Localize()
            .InFrench("Le name must be at least 3 characters long")
            .InCanadianFrench("Le name must be at least 3 characters long, éh")
            .In("de-DE", "Das name must be at least 3 characters long"));
        RuleFor(x => x.GPA).Must(x => x >= 0 && x <= 4.0).WithMessage(
            "Must be from 0 to 4".Localize()
            .InFrench("Must be from 0 to 4, comprendre?")
            .InCanadianFrench("Must be from 0 to 4, s'il vous plaît")
            .In("de-DE", "Must be from 0 to 4, verstehen?"));
var student = new Student()
    Name = "TJ",
    GPA = 4.1
var validator = new StudentValidator();
Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo(string.Empty); // invariant
var validationResult = validator.Validate(student);
Console.WriteLine(validationResult.Errors[0].ErrorMessage); // Name must be at least 3 characters long
Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo("de-DE");
validationResult = validator.Validate(student);
Console.WriteLine(validationResult.Errors[0].ErrorMessage); // Das name must be at least 3 characters long