把数据错误扼杀在早期，那就是在数据的入口处，一般数据都是打包成一个实体的方式进传递，FluentValidation就以实体类为单位进行属性验证的集合。
Install-Package FluentValidation
下面看一个例子吧。
实体类：
public class Person
{public int Id { get; set; }public DateTime Birthday { get; set; }public string IDCard { get; set; }public string Name { get; set; }public string Email { get; set; }public PersonAddress Address { get; set; }public string Tel { get; set; }
}
public class PersonAddress
{public string Country { get; set; }public string Province { get; set; }public string City { get; set; }public string County { get; set; }public string Address { get; set; }public string Postcode { get; set; }
}
验证实体类：
/// <summary>
/// Person验证
/// </summary>
public class PersonValidator : AbstractValidator<Person>
{public PersonValidator(){RuleFor(p => p.Name).NotNull();RuleFor(p => p.Email).NotNull().EmailAddress();RuleFor(p => p.Birthday).NotNull();RuleFor(p => p.IDCard).NotNull().When(p => (DateTime.Now > p.Birthday.AddYears(1))).WithMessage(p => $"出生日期为{p.Birthday}，现在时间为{DateTime.Now},大于一岁，CardID值必填！");RuleFor(p => p.Tel).NotNull().Matches(@"^(\d{3,4}-)?\d{6,8}$|^[1]+[3,4,5,8]+\d{9}$");RuleFor(p => p.Address).NotNull();RuleFor(p => p.Address).SetValidator(new PersonAddressValidator());}
}
/// <summary>
/// Person Address验证
/// </summary>
public class PersonAddressValidator : AbstractValidator<PersonAddress>
{public PersonAddressValidator(){RuleFor(a => a.Country).NotNull();RuleFor(a => a.Province).NotNull();RuleFor(a => a.City).NotNull();RuleFor(a => a.County).NotNull();RuleFor(a => a.Address).NotNull();RuleFor(a => a.Postcode).NotNull().Length(6);}
}
使用场景：
class Program
{static void Main(string[] args){var person = new Person(){//少一位Tel = "1345346711",Name = "桂素伟",//格式错误Email = "axzxs2001#163.com",//设置生日，没有身份证Birthday = DateTime.Parse("2020-03-28 00:00:00"),Address = new PersonAddress(){//邮编位数不对Postcode = "12345"},};var validator = new PersonValidator();var results = validator.Validate(person);if (!results.IsValid){foreach (var failure in results.Errors){Console.WriteLine("属性 " + failure.PropertyName + " 验证失败：" + failure.ErrorMessage);}}Console.WriteLine("--------------------------------------------------------------------");Console.WriteLine(results.ToString("\r\n"));}
}
FluentValidation有一个很赞的功能，就是验证某一属性时，可以用别的属性的值作为条件，组合实现验证，这样就能适应更多的业务逻辑验证场景。比如上例中的，只有大于一岁(Birthday)的人，身份证(IDCard)是必填项。当然FluentValidation不只这些功能，比如嵌套实体验证，组合验证规则等，都是很贴心的功能，期待大家尝试。
