C# Web开发教程(十二)数据校验机制

内置数据校验机制

• 框架内置了对数据校验的支持

- 在System.ComponentModel.DataAnnotations这个命名空间下:- 比如[Required]、[EmailAddress] 、[RegularExpression] 、 CustomValidationAttribute、IValidatableObject等待

• demo演示

// LoginRequest1.csusing System.ComponentModel.DataAnnotations;namespace WebApplicationAboutDataValidate
{public class LoginRequest1{[Required][EmailAddress][RegularExpression("^.*@(qq|163)\\.com$", ErrorMessage = "只支持QQ和163邮箱")]public string Email { get; set; }[Required][StringLength(10, MinimumLength = 3)]public string Password { get; set; }[Compare(nameof(Password2), ErrorMessage = "两次密码必须一致")]public string Password2 { get; set; }}
}

• 测试效果

- 提交如下字段{"email": "user@example.com","password": "string","password2": "string"
}- 返回:{"type": "https://tools.ietf.org/html/rfc7231#section-6.5.1","title": "One or more validation errors occurred.","status": 400,"traceId": "00-840f868ea1c247a51f659d0092a68ae9-a7f61df6b9a99cd3-00","errors": {"Email": ["只支持QQ和163邮箱"]}
}- 提交如下字段:{"email": "user@qq.com","password": "string123","password2": "string"
}- 返回:{"type": "https://tools.ietf.org/html/rfc7231#section-6.5.1","title": "One or more validation errors occurred.","status": 400,"traceId": "00-e635ad8de5684008becbe67b9be814e8-fea276f49eca5228-00","errors": {"Password2": ["两次密码必须一致"]}
}

• 内置数据校验机制的问题点

- 校验规则都是和模型类耦合在一起，违反“单一职责原则”；
- 很多常用的校验都需要编写自定义校验规则，而且写起来麻烦。

数据校验机制第三方库--- FluentValidation1

• FluentValidation在很多项目中都可以使用(比如WinForm,WPF)

• 注意事项: FluentValidation可以和内置的数据校验机制混用,但最好不要这么干,避免混淆和未知的坑.

• 安装库

- Install-Package Microsoft.EntityFrameworkCore.Tools -Version 6.0.0
-  Install-Package FluentValidation.AspNetCore -Version 10.3.4 // 这里不要搞成6的版本,有坑

• Program.cs注册一下

// LoginRequest1.cs
using System.ComponentModel.DataAnnotations;namespace WebApplicationAboutDataValidate
{public class LoginRequest1{public string Email { get; set; }public string UserName { get; set; }public string Password { get; set; }public string Password2 { get; set; }}
}// AddNewUserRequestValidator.cs---自定义校验器using FluentValidation;namespace WebApplicationAboutDataValidate
{public class AddNewUserRequestValidator : AbstractValidator<LoginRequest1>{public AddNewUserRequestValidator(){RuleFor(x => x.Email).NotNull().EmailAddress().WithMessage("邮箱必须是合法地址").Must(x => x.EndsWith("@163.com") || x.EndsWith("@qq.com")).WithMessage("支持163或者QQ邮箱");RuleFor(x => x.UserName).NotNull().Length(3,10);RuleFor(x => x.Password).Equal(x => x.Password2).WithMessage("两次密码必须一致");}}
}// Program.cs
......
builder.Services.AddSwaggerGen();
// 注册全局验证器
builder.Services.AddFluentValidation(fv => {Assembly assembly = Assembly.GetExecutingAssembly();fv.RegisterValidatorsFromAssembly(assembly);
});
var app = builder.Build();
......// 测试接口using Microsoft.AspNetCore.Mvc;namespace WebApplicationAboutDataValidate.Controllers
{[ApiController][Route("[controller]/[action]")]public class ValidateDataController : ControllerBase{[HttpPost]public ActionResult Login(LoginRequest1 req){return Ok(req);}}
}

- 测试: https://localhost:7263/ValidateData/Login{"email": "string","userName": "string","password": "string","password2": "string111"
}- 返回结果{"type": "https://tools.ietf.org/html/rfc7231#section-6.5.1","title": "One or more validation errors occurred.","status": 400,"traceId": "00-7666f45f49e7afcab428d6bbd34d5bfb-1d6ed200ab8f73e3-00","errors": {"Email": ["邮箱必须是合法地址","支持163或者QQ邮箱"],"Password": ["两次密码必须一致"]}
}

• FluentValidation + DI高级功能---依赖注入: 可以通过构造方法来向校验器注入服务

using FluentValidation;
using Microsoft.AspNetCore.Identity;namespace WebApplicationAboutDataValidate
{public class AddNewUserRequestValidator : AbstractValidator<LoginRequest1>{public AddNewUserRequestValidator(UserManager<LoginRequest1> userManager){RuleFor(x => x.Email).NotNull().EmailAddress().WithMessage("邮箱必须是合法地址").Must(x => x.EndsWith("@163.com") || x.EndsWith("@qq.com")).WithMessage("支持163或者QQ邮箱");RuleFor(x => x.UserName).NotNull().Length(3,10).MustAsync(async (x,_) => await userManager.FindByNameAsync(x) == null).WithMessage("用户名已存在");//RuleFor(x => x.Password).Equal(x => x.Password2).WithMessage("两次密码必须一致");RuleFor(x => x.Password).Equal(x => x.Password2).WithMessage(x => $"密码{x.Password}和{x.Password2}不一致");}}
}

核心要点总结

1. 分离关注点：FluentValidation 将校验逻辑从模型类中分离出来
2. 链式编程：使用流畅的接口设计，代码可读性更强
3. 灵活性强：支持复杂的业务逻辑校验，包括异步校验
4. 错误信息定制：可以灵活定制错误消息，支持动态消息
5. 依赖注入支持：可以在校验器中注入服务，实现更复杂的业务校验