为了验证api post上来的数据的有效性，我们可以引入FluentValidation(详见https://fluentvalidation.net)。在asp.net mvc中，使用的是模型验证，通过在实体类上添加特性达到验证效果。
FluentValidation的原理是通过实现AbstractValidator<T>来实现对T实体类的验证，通过不同折Rule来验证T中的属性（更多验证规则 ，参见官网），见如下实现：
public class Person
{public int Id { get; set; }public string Name { get; set; }public string Tel { get; set; }public string Email { get; set; }public DateTime Birthday { get; set; }public string IDCard { get; set; }public PersonAddress Address { 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; }
}/// <summary>
/// Person验证
/// </summary>
public class PersonValidator : AbstractValidator<Person>
{public PersonValidator(IPersonService personService){RuleFor(p => p.Name).NotNull().NotEmpty();RuleFor(p => p.Email).NotNull().EmailAddress();RuleFor(p => p.Birthday).NotNull();RuleFor(p => p.IDCard).NotNull().NotEmpty().Length(18).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}$").WithMessage("电话格式为：0000-0000000或13000000000");RuleFor(p => p.Address).NotNull();RuleFor(p => p.Address).SetValidator(new PersonAddressValidator());//通过调用外部方法来验证RuleFor(p => p.Id).Must(id => personService.IsExist(id)).WithMessage(p => $"不存在id={p.Id}的用户");}
}
/// <summary>
/// Person Address验证
/// </summary>
public class PersonAddressValidator : AbstractValidator<PersonAddress>
{public PersonAddressValidator(){RuleFor(a => a.Country).NotNull().NotEmpty();RuleFor(a => a.Province).NotNull().NotEmpty();RuleFor(a => a.City).NotNull().NotEmpty();RuleFor(a => a.County).NotNull().NotEmpty();RuleFor(a => a.Address).NotNull().NotEmpty();RuleFor(a => a.Postcode).NotNull().NotEmpty().Length(6);}
}在mini api引入FluentValidation也很简单，可以通过注入IValidator<T>实现，也可以注放AddFluentValidation，用IValidatorFactory来获取Validator来实现验证，代码如下：
using FluentValidation;
using FluentValidation.AspNetCore;
using System.Text;var builder = WebApplication.CreateBuilder(args);
builder.Services.AddFluentValidation();
builder.Services.AddScoped<IValidator<Person>, PersonValidator>();
builder.Services.AddScoped<IPersonService, PersonService>();
var app = builder.Build();app.MapPost("/person", async (IValidator<Person> validator, Person person) =>{var result = await validator.ValidateAsync(person);if (!result.IsValid){var errors = new StringBuilder();foreach (var valid in result.Errors){errors.AppendLine(valid.ErrorMessage);}return errors.ToString();}return "OK";});app.MapPost("/person1", async (IValidatorFactory validatorFactory, Person person) =>
{var result = await validatorFactory.GetValidator<Person>().ValidateAsync(person);if (!result.IsValid){var errors = new StringBuilder();foreach (var valid in result.Errors){errors.AppendLine(valid.ErrorMessage);}return errors.ToString();}return "OK";
});app.MapPost("/person2", async (IValidatorFactory validatorFactory, Person person) =>
{var result = await validatorFactory.GetValidator(typeof(Person)).ValidateAsync(new ValidationContext<Person>(person));if (!result.IsValid){var errors = new StringBuilder();foreach (var valid in result.Errors){errors.AppendLine(valid.ErrorMessage);}return errors.ToString();}return "OK";
});app.Run();public interface IPersonService
{public bool IsExist(int id);
}
public class PersonService : IPersonService
{public bool IsExist(int id){if (DateTime.Now.Second % 2 == 0){return false;}else{return true;}}
}
)
