Validating multiple properties with FluentValidation(FluentValidator多个相关属性校验)

public class FooBarRequestValidator : AbstractValidator<FooBarRequest>
{
    private readonly IRepository repository;

    public FooBarRequestValidator(IRepository repository)
    {
        this.repository = repository;

        RuleFor(x => x.Foo)
        .Must(NotAlreadyHaveABar)
        .WithMessage("You already have a bar for this foo.");
    }

    private bool NotAlreadyHaveABar(FooBarRequest instance, string foo)
    {
        return !repository.GetAll<FooBar>()
        .Any(x => x.Foo == foo && x.Bar == instance.Bar);
    }
}