public IEnumerable <ValidationResult> Validate(ValidationContext validationContext) { return(ValidationRules.Validate(validationContext, new PostalCodeRule(PostalCode, Country, nameof(PostalCode), nameof(Country)), ValidationRule.For( (cxt) => cxt.GetSevice <AddressService>()?.PostalCodeExists(PostalCode), () => "Postal code does not exist.", nameof(PostalCode)))); }