学习ASP.NET Core(06)-Restful与WebAPI

上一篇我们使用Swagger添加了接口文档，使用Jwt完成了授权，本章我们简答介绍一下RESTful风格的WebAPI开发过程中涉及到的一些知识点，并完善一下尚未完成的功能

.NET下的WebAPI是一种无限接近RESTful风格的框架，RESTful风格它有着自己的一套理论，它的大概意思就是说使用标准的Http方法，将Web系统的服务抽象为资源。稍微具体一点的介绍可以查看阮一峰的这篇文章RESTful API最佳实践。我们这里就分几部分介绍一下构建RESTful API需要了解的基础知识

注：本章介绍部分的内容大多是基于solenovex的使用 ASP.NET Core 3.x 构建 RESTful Web API视频内容的整理，若想进一步了解相关知识，请查看原视频

一、HTTP方法

1、什么是HTTP方法

HTTP方法是对Web服务器的说明，说明如何处理请求的资源。HTTP1.0 定义了三种请求方法： GET, POST 和 HEAD方法；HTTP1.1 新增了六种请求方法：OPTIONS、PUT、PATCH、DELETE、TRACE 和 CONNECT 方法。

2、常用的HTTP方法

GET：通常用来获取资源；GET请求会返回请求路径对应的资源，但它分两种情况：

①获取单个资源，通过使用URL的形式带上唯一标识，示例：api/Articles/{ArticleId}；

②获取集合资源中符合条件的资源，会通过QueryString的形式在URL后面添加？查询条件作为筛选条件，示例：api/Articles?title=WebAPI
POST：通常用来创建资源；POST的参数会放在请求body中，POST请求应该返回新创建的资源以及可以获取该资源的唯一标识URL，示例：api/Articles/
DELETE：通常用来移除/删除对应路径的资源；通过使用URL的形式带上唯一标识，或者和GET一样使用QueryString，处理完成后通常不会返回资源，只返回状态码204，示例：api/Articles/{ArticleId}；
PUT：通常用来完全替换对应路径的资源信息；POST的参数会放在请求body中，且为一个完整对象，示例：api/Articles/{ArticleId}；与此同时，它分两类情况：

①对应的资源不存在，则新增对应的资源，后续处理和POST一样；

②对应的资源存在，则替换对应的资源，处理完成不需要返回信息，只返回状态码204
PATCH：通常用来更新对应路径资源的局部信息；PATCH的参数会放在请求头中，处理完成后通常不会返回资源，只返回状态码204，示例：api/Articles/{ArticleId}；

综上：给出一张图例，来自solenovex，使用 ASP.NET Core 3.x 构建 RESTful Web API

3、安全性和幂等性

安全性是指方法执行后不会改变资源的表述；幂等性是指方法无论执行多少次都会得到相同的结果

二、状态码相关

1、状态码

HTTP状态码是表示Web服务器响应状态的3位数字代码。通常会以第一位数字为区分

1xx：属于信息性的状态码，WebAPI不使用

2xx：表示请求执行成功，常用的有200—请求成功，201—创建成功，204—请求成功无返回信息，如删除

3xx：用于跳转，如告诉搜索引擎，网址已改变。大多数WebAPI不需要使用这类状态码

4xx：表示客户端错误

400：Bad Request，表示API用户发送到服务器的请求存在错误；
401：Unauthorized，表示没有提供授权信息，或者授权信息不正确；
403：Forbidden，表示身份认证成功，但是无权限访问请求的资源
404：Not Found，表示请求的资源不存在
405：Method not allowed，表示使用了不被支持的HTTP方法
406：Not Acceptable，表示API用户请求的格式WebAPI不支持，且WebAPI不提供默认的表述格式
409：Conflict，表示冲突，一般用来表述并发问题，如修改资源期间，资源被已经被更新了
415：Unsupported Media Type，与406相反，表示服务器接受的资源WebAPI不支持
422：Unprocessable Entity，表示服务器已经解析了内容，但是无法处理，如实体验证错误

5xx：表示服务器错误

500：INternal Server Error：表示服务器发生了错误，客户端无法处理

2、错误与故障

基于HTTP请求状态码，我们需要了解一下错误和故障的区别

错误：API正常工作，但是API用户请求传递的数据不合理，所以请求被拒绝。对应4xx错误；

故障：API工作异常，API用户请求是合理的，但是API无法响应。对应5xx错误

3、故障处理

我们可以在非开发环境进行如下配置，以确保生产环境异常时能查看到相关异常说明，通常这里会写入日志记录异常，我们会在后面的章节添加日志功能，这里先修改如下：

三、WebAPI相关

1、内容协商

什么是内容协商？即当有多种表述格式(Json/Xml等)可用时，选取最佳的一个进行表述。简单来说就是请求什么格式，服务端就返回什么格式的数据；
如何设置内容协商？首先我们要从服务端的角度区分输出和输入，输出表示客户端发出请求服务端响应数据；输入表示客户端提交数据服务端对其进行处理；举例来说，Get就是输出，Post就是输入

先看输出：在Http请求的Header中有一个Accept Header属性，如该属性设置的是application/json，那么API返回的就应该是Json格式的；在ASP.NET Core中负责响应输出格式的就是Output Formatters对象
再看输入：HTTP请求的输入格式对应的是Content-Type Header属性，ASP.NET Core中负责响应输入格式的就是Input Formatters对象

PS：如果没有设置请求格式，就返回默认格式；而如果请求的格式不存在，则应当返回406状态码；

2、内容协商设置

ASP.NET Core目前的设置是仅返回Json格式信息，不支持XML；如果请求的是XML或没有设置，它同样会返回Json；如果希望关闭此项设置，即不存在返回406状态码，可以在Controller服务注册时添加如下设置；

而如果希望支持输出和输入都支持XML格式，可以配置如下：

3、对象绑定

客户端数据可以通过多种方式传递给API，Binding Source Attribute则是负责处理绑定的对象，它会为告知Model的绑定引擎，从哪里可以找到绑定源，Binding Source Attribute一共有六种绑定数据来源，如下：

FromBody：从请求的Body中获取绑定数据
FromForm：从请求的Body中的form获取绑定数据
FromHeader：从请求的Header中获取绑定数据
FromQuery：从QueryString参数中获取绑定数据
FromRoute：从当前请求的路由中获取绑定数据
FromService：从作为Action参数而注入的服务中获取绑定数据

4、ApiController特性

ASP.NET Core WebAPI中我们通常会使用[ApiController]特性来修饰我们的Controller对象，该特性为了更好的适应API方法，对上述分类规则进行了修改，修改如下：

FormBody：通常用来推断复杂类型的参数
FromForm：通常用来推断IFormFilr和IFormFileColllection类型的Action参数，即文件上传相对应的参数
FromRoute：通常用来推断Action的参数名和路由模板中的参数名一致的情况
FromQuery：用来推断其他的Action参数

一些特殊情况，需要手动指明对象的来源，如在HttpGet方法中，查询参数是一个复杂的类类型，则ApiController对象会默认绑定源为请求body，这时候就需要手动指明绑定源为FromQuery；

5、输入验证

通常我们会使用一些验证规则对客户端的输入内容进行限制，像用户名不能包含特殊字符，用户名长度等

1、验证规则

WebAPI中内置了一组名为Data Annotations的验证规则，像之前我们添加的[Required]，[StringLength...]都属于这个类型。或者我们可以自定义一个类，实现IValidatableObject接口，对多个字段进行限制；当然我们也可以针对类或者是属性自定义一些验证规则，需要继承ValidationAttribute类重写IsValid方法

2、验证检查

检查时会使用ModelState对象，它是一个字典，包含model的状态和model的绑定验证信息；同时它还包含针对每个提交的属性值的错误信息的集合，每当有请求进来的时候，定义好的验证规则就会被检查。如果验证不通过，ModelState.IsValid()就会返回false；

3、报告验证错误

如发生验证错误，应当返回Unprocessable Entity 422错误，并在响应的body中包含验证错误信息；ASP.NET Core已经定义好了这部分内容，当Controller使用[ApiController]属性进行注解时，如果遇到错误，那么将会自返回400错误状态码

四、完成Controller基础功能

controller功能的实现是大多基于对BLL层的引用，虽然我们在第3小结中已经实现了数据层和逻辑层的基础功能，但在Controller实现时还是发现了很多不合理的地方，所以调整了很多内容，下面我们依次来看一下

1、UserController

1、首先对Model的层进行了调整，调整了出生日期和性别的默认值

using System;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model
{
    /// <summary>
    /// 用户
    /// </summary>
    public class User : BaseEntity
    {
        /// <summary>
        /// 账户
        /// </summary>
        [Required, StringLength(40)]
        public string Account { get; set; }
        /// <summary>
        /// 密码
        /// </summary>
        [Required, StringLength(200)]
        public string Password { get; set; }
        /// <summary>
        /// 头像
        /// </summary>
        public string ProfilePhoto { get; set; }
        /// <summary>
        /// 出生日期
        /// </summary>
        public DateTime BirthOfDate { get; set; } = DateTime.Today;

        /// <summary>
        /// 性别
        /// </summary>
        public Gender Gender { get; set; } = Gender.保密;
        /// <summary>
        /// 用户等级
        /// </summary>
        public Level Level { get; set; } = Level.普通用户;
        /// <summary>
        /// 粉丝数
        /// </summary>
        public int FansNum { get; set; }
        /// <summary>
        /// 关注数
        /// </summary>
        public int FocusNum { get; set; }
    }
}

对ViewModel进行了调整，如下：

using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 用户注册
    /// </summary>
    public class RegisterViewModel
    {
        /// <summary>
        /// 账号
        /// </summary>
        [Required, StringLength(40, MinimumLength = 4)]
        [RegularExpression(@"/^([\u4e00-\u9fa5]{2,4})|([A-Za-z0-9_]{4,16})|([a-zA-Z0-9_\u4e00-\u9fa5]{3,16})$/")]
        public string Account { get; set; }

        /// <summary>
        /// 密码
        /// </summary>
        [Required, StringLength(20, MinimumLength = 6)]
        public string Password { get; set; }

        /// <summary>
        /// 确认密码
        /// </summary>
        [Required, Compare(nameof(Password))]
        public string RequirePassword { get; set; }
    }
}

using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 用户登录
    /// </summary>
    public class LoginViewModel
    {
        /// <summary>
        /// 用户名称
        /// </summary>
        [Required, StringLength(40, MinimumLength = 4)]
        [RegularExpression(@"/^([\u4e00-\u9fa5]{2,4})|([A-Za-z0-9_]{4,16})|([a-zA-Z0-9_\u4e00-\u9fa5]{3,16})$/")]
        public string Account { get; set; }

        /// <summary>
        /// 用户密码
        /// </summary>
        [Required, StringLength(20, MinimumLength = 6), DataType(DataType.Password)]
        public string Password { get; set; }
    }
}

using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 修改用户密码
    /// </summary>
    public class ChangePwdViewModel
    {
        /// <summary>
        /// 旧密码
        /// </summary>
        [Required]
        public string OldPassword { get; set; }

        /// <summary>
        /// 新密码
        /// </summary>
        [Required]
        public string NewPassword { get; set; }

        /// <summary>
        /// 确认新密码
        /// </summary>
        [Required, Compare(nameof(NewPassword))]
        public string RequirePassword { get; set; }
    }
}

using System;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 修改用户资料
    /// </summary>
    public class ChangeUserInfoViewModel
    {
        /// <summary>
        /// 账号
        /// </summary>
        public string Account { get; set; }

        /// <summary>
        /// 出生日期
        /// </summary>
        [DataType(DataType.Date)]
        public DateTime BirthOfDate { get; set; }

        /// <summary>
        /// 性别
        /// </summary>
        public Gender Gender { get; set; }
    }
}

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 用户详细信息
    /// </summary>
    public class UserDetailsViewModel
    {
        /// <summary>
        /// 账号
        /// </summary>
        public string Account { get; set; }
        /// <summary>
        /// 头像
        /// </summary>
        public string ProfilePhoto { get; set; }
        /// <summary>
        /// 年龄
        /// </summary>
        public int Age { get; set; }
        /// <summary>
        /// 性别
        /// </summary>
        public string Gender { get; set; }
        /// <summary>
        /// 用户等级
        /// </summary>
        public string Level { get; set; }
        /// <summary>
        /// 粉丝数
        /// </summary>
        public int FansNum { get; set; }
        /// <summary>
        /// 关注数
        /// </summary>
        public int FocusNum { get; set; }
    }
}

2、IBLL和BLL层调整如下：

using System;
using BlogSystem.Model;
using BlogSystem.Model.ViewModels;
using System.Threading.Tasks;

namespace BlogSystem.IBLL
{
    /// <summary>
    /// 用户服务接口
    /// </summary>
    public interface IUserService : IBaseService<User>
    {
        /// <summary>
        /// 注册
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        Task<bool> Register(RegisterViewModel model);

        /// <summary>
        /// 登录成功返回userId
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        Task<Guid> Login(LoginViewModel model);

        /// <summary>
        /// 修改用户密码
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<bool> ChangePassword(ChangePwdViewModel model, Guid userId);

        /// <summary>
        /// 修改用户头像
        /// </summary>
        /// <param name="profilePhoto"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<bool> ChangeUserPhoto(string profilePhoto, Guid userId);

        /// <summary>
        /// 修改用户信息
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<bool> ChangeUserInfo(ChangeUserInfoViewModel model, Guid userId);

        /// <summary>
        /// 使用account获取用户信息
        /// </summary>
        /// <param name="account"></param>
        /// <returns></returns>
        Task<UserDetailsViewModel> GetUserInfoByAccount(string account);
    }
}

using BlogSystem.Common.Helpers;
using BlogSystem.IBLL;
using BlogSystem.IDAL;
using BlogSystem.Model;
using BlogSystem.Model.ViewModels;
using Microsoft.EntityFrameworkCore;
using System;
using System.Linq;
using System.Threading.Tasks;

namespace BlogSystem.BLL
{
    public class UserService : BaseService<User>, IUserService
    {
        private readonly IUserRepository _userRepository;

        public UserService(IUserRepository userRepository)
        {
            _userRepository = userRepository;
            BaseRepository = userRepository;
        }

        /// <summary>
        /// 用户注册
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        public async Task<bool> Register(RegisterViewModel model)
        {
            //判断账户是否存在
            if (await _userRepository.GetAll().AnyAsync(m => m.Account == model.Account))
            {
                return false;
            }
            var pwd = Md5Helper.Md5Encrypt(model.Password);
            await _userRepository.CreateAsync(new User
            {
                Account = model.Account,
                Password = pwd
            });
            return true;
        }

        /// <summary>
        /// 用户登录
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        public async Task<Guid> Login(LoginViewModel model)
        {
            var pwd = Md5Helper.Md5Encrypt(model.Password);
            var user = await _userRepository.GetAll().FirstOrDefaultAsync(m => m.Account == model.Account && m.Password == pwd);
            return user == null ? new Guid() : user.Id;
        }

        /// <summary>
        /// 修改用户密码
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<bool> ChangePassword(ChangePwdViewModel model, Guid userId)
        {
            var oldPwd = Md5Helper.Md5Encrypt(model.OldPassword);
            var user = await _userRepository.GetAll().FirstOrDefaultAsync(m => m.Id == userId && m.Password == oldPwd);
            if (user == null)
            {
                return false;
            }
            var newPwd = Md5Helper.Md5Encrypt(model.NewPassword);
            user.Password = newPwd;
            await _userRepository.EditAsync(user);
            return true;
        }

        /// <summary>
        /// 修改用户照片
        /// </summary>
        /// <param name="profilePhoto"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<bool> ChangeUserPhoto(string profilePhoto, Guid userId)
        {
            var user = await _userRepository.GetAll().FirstOrDefaultAsync(m => m.Id == userId);
            if (user == null) return false;
            user.ProfilePhoto = profilePhoto;
            await _userRepository.EditAsync(user);
            return true;
        }

        /// <summary>
        ///  修改用户信息
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<bool> ChangeUserInfo(ChangeUserInfoViewModel model, Guid userId)
        {
            //确保用户名唯一
            if (await _userRepository.GetAll().AnyAsync(m => m.Account == model.Account))
            {
                return false;
            }
            var user = await _userRepository.GetOneByIdAsync(userId);
            user.Account = model.Account;
            user.Gender = model.Gender;
            user.BirthOfDate = model.BirthOfDate;
            await _userRepository.EditAsync(user);
            return true;
        }

        /// <summary>
        /// 通过账号名称获取用户信息
        /// </summary>
        /// <param name="account"></param>
        /// <returns></returns>
        public async Task<UserDetailsViewModel> GetUserInfoByAccount(string account)
        {
            if (await _userRepository.GetAll().AnyAsync(m => m.Account == account))
            {
                return await _userRepository.GetAll().Where(m => m.Account == account).Select(m =>
                    new UserDetailsViewModel()
                    {
                        Account = m.Account,
                        ProfilePhoto = m.ProfilePhoto,
                        Age = DateTime.Now.Year - m.BirthOfDate.Year,
                        Gender = m.Gender.ToString(),
                        Level = m.Level.ToString(),
                        FansNum = m.FansNum,
                        FocusNum = m.FocusNum
                    }).FirstAsync();
            }
            return new UserDetailsViewModel();
        }
    }
}

3、Controller层功能的实现大多数需要基于UserId，我们怎么获取UserId呢？还记得Jwt吗？客户端发送请求时会在Header中带上Jwt字符串，我们可以解析该字符串得到用户名。在自定义的JwtHelper中我们实现了两个方法，一个是加密Jwt，一个是解密Jwt，我们对解密方法进行调整，如下：

        /// <summary>
        /// Jwt解密
        /// </summary>
        /// <param name="jwtStr"></param>
        /// <returns></returns>
        public static TokenModelJwt JwtDecrypt(string jwtStr)
        {
            if (string.IsNullOrEmpty(jwtStr) || string.IsNullOrWhiteSpace(jwtStr))
            {
                return new TokenModelJwt();
            }
            jwtStr = jwtStr.Substring(7);//截取前面的Bearer和空格
            var jwtHandler = new JwtSecurityTokenHandler();
            JwtSecurityToken jwtToken = jwtHandler.ReadJwtToken(jwtStr);

            jwtToken.Payload.TryGetValue(ClaimTypes.Role, out object level);

            var model = new TokenModelJwt
            {
                UserId = Guid.Parse(jwtToken.Id),
                Level = level == null ? "" : level.ToString()
            };
            return model;
        }

在对应的Contoneller中我们可以使用HttpContext对象获取Http请求的信息，但是HttpContext的使用是需要注册的，在StartUp的ConfigureServices中进行注册，services.AddHttpContextAccessor();之后在对应的控制器构造函数中进行注入IHttpContextAccessor对象即可，如下：

using BlogSystem.Core.Helpers;
using BlogSystem.IBLL;
using BlogSystem.Model.ViewModels;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Threading.Tasks;

namespace BlogSystem.Core.Controllers
{
    [ApiController]
    [Route("api/user")]
    public class UserController : ControllerBase
    {
        private readonly IUserService _userService;
        private readonly Guid _userId;

        public UserController(IUserService userService, IHttpContextAccessor httpContext)
        {
            _userService = userService ?? throw new ArgumentNullException(nameof(userService));
            var accessor = httpContext ?? throw new ArgumentNullException(nameof(httpContext));
            _userId = JwtHelper.JwtDecrypt(accessor.HttpContext.Request.Headers["Authorization"]).UserId;
        }

        /// <summary>
        /// 用户注册
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        [HttpPost(nameof(Register))]
        public async Task<IActionResult> Register(RegisterViewModel model)
        {
            if (!await _userService.Register(model))
            {
                return Ok("用户已存在");
            }
            //创建成功返回到登录方法，并返回注册成功的account
            return CreatedAtRoute(nameof(Login), model.Account);
        }

        /// <summary>
        /// 用户登录
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        [HttpPost("Login", Name = nameof(Login))]
        public async Task<IActionResult> Login(LoginViewModel model)
        {
            //判断账号密码是否正确
            var userId = await _userService.Login(model);
            if (userId == Guid.Empty) return Ok("账号或密码错误！");

            //登录成功进行jwt加密
            var user = await _userService.GetOneByIdAsync(userId);
            TokenModelJwt tokenModel = new TokenModelJwt { UserId = user.Id, Level = user.Level.ToString() };
            var jwtStr = JwtHelper.JwtEncrypt(tokenModel);
            return Ok(jwtStr);
        }

        /// <summary>
        /// 获取用户信息
        /// </summary>
        /// <param name="account"></param>
        /// <returns></returns>
        [HttpGet("{account}")]
        public async Task<IActionResult> UserInfo(string account)
        {
            var list = await _userService.GetUserInfoByAccount(account);
            if (string.IsNullOrEmpty(list.Account))
            {
                return NotFound();
            }
            return Ok(list);
        }

        /// <summary>
        /// 修改用户密码
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        [Authorize]
        [HttpPatch("password")]
        public async Task<IActionResult> ChangePassword(ChangePwdViewModel model)
        {
            if (!await _userService.ChangePassword(model, _userId))
            {
                return NotFound("用户密码错误！");
            }
            return NoContent();
        }

        /// <summary>
        /// 修改用户照片
        /// </summary>
        /// <param name="profilePhoto"></param>
        /// <returns></returns>
        [Authorize]
        [HttpPatch("photo")]
        public async Task<IActionResult> ChangeUserPhoto([FromBody]string profilePhoto)
        {
            if (!await _userService.ChangeUserPhoto(profilePhoto, _userId))
            {
                return NotFound();
            }
            return NoContent();
        }

        /// <summary>
        ///  修改用户信息
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        [Authorize]
        [HttpPatch("info")]
        public async Task<IActionResult> ChangeUserInfo(ChangeUserInfoViewModel model)
        {
            if (!await _userService.ChangeUserInfo(model, _userId))
            {
                return Ok("用户名已存在");
            }
            return NoContent();
        }
    }
}

2、分类Controller

1、调整ViewModel层如下：

using System;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 编辑分类
    /// </summary>
    public class EditCategoryViewModel
    {
        /// <summary>
        /// 分类Id
        /// </summary>
        public Guid CategoryId { get; set; }

        /// <summary>
        /// 分类名称
        /// </summary>
        [Required, StringLength(30, MinimumLength = 2)]
        public string CategoryName { get; set; }
    }
}

using System;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 分类列表
    /// </summary>
    public class CategoryListViewModel
    {
        /// <summary>
        /// 分类Id
        /// </summary>
        public Guid CategoryId { get; set; }

        /// <summary>
        /// 分类名称
        /// </summary>
        [Required, StringLength(30, MinimumLength = 2)]
        public string CategoryName { get; set; }
    }
}

using System;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 创建文章分类
    /// </summary>
    public class CreateCategoryViewModel
    {
        /// <summary>
        /// 分类Id
        /// </summary>
        public Guid CategoryId { get; set; }

        /// <summary>
        /// 分类名称
        /// </summary>
        [Required, StringLength(30, MinimumLength = 2)]
        public string CategoryName { get; set; }
    }
}

2、调整IBLL和BLL层如下：

using BlogSystem.Model;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using BlogSystem.Model.ViewModels;

namespace BlogSystem.IBLL
{
    /// <summary>
    /// 分类服务接口
    /// </summary>
    public interface ICategoryService : IBaseService<Category>
    {
        /// <summary>
        /// 创建分类
        /// </summary>
        /// <param name="categoryName"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<Guid> CreateCategory(string categoryName, Guid userId);

        /// <summary>
        /// 编辑分类
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<bool> EditCategory(EditCategoryViewModel model, Guid userId);

        /// <summary>
        /// 通过用户Id获取所有分类
        /// </summary>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<List<CategoryListViewModel>> GetCategoryByUserIdAsync(Guid userId);
    }
}

using BlogSystem.IBLL;
using BlogSystem.IDAL;
using BlogSystem.Model;
using BlogSystem.Model.ViewModels;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace BlogSystem.BLL
{
    public class CategoryService : BaseService<Category>, ICategoryService
    {
        private readonly ICategoryRepository _categoryRepository;

        public CategoryService(ICategoryRepository categoryRepository)
        {
            _categoryRepository = categoryRepository;
            BaseRepository = categoryRepository;
        }

        /// <summary>
        /// 创建分类
        /// </summary>
        /// <param name="categoryName"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<Guid> CreateCategory(string categoryName, Guid userId)
        {
            //当前用户存在该分类名称则返回
            if (string.IsNullOrEmpty(categoryName) || await _categoryRepository.GetAll()
                .AnyAsync(m => m.UserId == userId && m.CategoryName == categoryName))
            {
                return Guid.Empty;
            }
            //创建成功返回分类Id
            var categoryId = Guid.NewGuid();
            await _categoryRepository.CreateAsync(new Category
            {
                Id = categoryId,
                UserId = userId,
                CategoryName = categoryName
            });
            return categoryId;
        }

        /// <summary>
        ///  编辑分类
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<bool> EditCategory(EditCategoryViewModel model, Guid userId)
        {
            //用户不存在该分类则返回
            if (!await _categoryRepository.GetAll().AnyAsync(m => m.UserId == userId && m.Id == model.CategoryId))
            {
                return false;
            }

            await _categoryRepository.EditAsync(new Category
            {
                UserId = userId,
                Id = model.CategoryId,
                CategoryName = model.CategoryName
            });
            return true;
        }

        /// <summary>
        ///  通过用户Id获取所有分类
        /// </summary>
        /// <param name="userId"></param>
        /// <returns></returns>
        public Task<List<CategoryListViewModel>> GetCategoryByUserIdAsync(Guid userId)
        {
            return _categoryRepository.GetAll().Where(m => m.UserId == userId).Select(m => new CategoryListViewModel
            {
                CategoryId = m.Id,
                CategoryName = m.CategoryName
            }).ToListAsync();
        }
    }
}

3、调整Controller功能如下：

using BlogSystem.Core.Helpers;
using BlogSystem.IBLL;
using BlogSystem.Model.ViewModels;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Threading.Tasks;

namespace BlogSystem.Core.Controllers
{
    [ApiController]
    [Route("api/category")]
    public class CategoryController : ControllerBase
    {
        private readonly ICategoryService _categoryService;
        private readonly IArticleService _aeArticleService;
        private readonly Guid _userId;

        public CategoryController(ICategoryService categoryService, IArticleService articleService,
            IHttpContextAccessor httpContext)
        {
            _categoryService = categoryService ?? throw new ArgumentNullException(nameof(categoryService));
            _aeArticleService = articleService ?? throw new ArgumentNullException(nameof(articleService));
            var accessor = httpContext ?? throw new ArgumentNullException(nameof(httpContext));
            _userId = JwtHelper.JwtDecrypt(accessor.HttpContext.Request.Headers["Authorization"]).UserId;
        }

        /// <summary>
        /// 查询用户的文章分类
        /// </summary>
        /// <param name="userId"></param>
        /// <returns></returns>
        [HttpGet("{userId}", Name = nameof(GetCategoryByUserId))]
        public async Task<IActionResult> GetCategoryByUserId(Guid userId)
        {
            if (userId == Guid.Empty)
            {
                return NotFound();
            }
            var list = await _categoryService.GetCategoryByUserIdAsync(userId);
            return Ok(list);
        }

        /// <summary>
        /// 新增文章分类
        /// </summary>
        /// <param name="categoryName"></param>
        /// <returns></returns>
        [Authorize]
        [HttpPost]
        public async Task<IActionResult> CreateCategory([FromBody]string categoryName)
        {
            var categoryId = await _categoryService.CreateCategory(categoryName, _userId);
            if (categoryId == Guid.Empty)
            {
                return BadRequest("重复分类！");
            }
            //创建成功返回查询页面链接
            var category = new CreateCategoryViewModel { CategoryId = categoryId, CategoryName = categoryName };
            return CreatedAtRoute(nameof(GetCategoryByUserId), new { userId = _userId }, category);
        }

        /// <summary>
        /// 删除分类
        /// </summary>
        /// <param name="categoryId"></param>
        /// <returns></returns>
        [Authorize]
        [HttpDelete("{categoryId}")]
        public async Task<IActionResult> RemoveCategory(Guid categoryId)
        {
            //确认是否存在，操作人与归属人是否一致
            var category = await _categoryService.GetOneByIdAsync(categoryId);
            if (category == null || category.UserId != _userId)
            {
                return NotFound();
            }
            //有文章使用了该分类，无法删除
            var data = await _aeArticleService.GetArticlesByCategoryIdAsync(_userId, categoryId);
            if (data.Count > 0)
            {
                return BadRequest("存在使用该分类的文章！");
            }

            await _categoryService.RemoveAsync(categoryId);
            return NoContent();
        }

        /// <summary>
        /// 编辑分类
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        [Authorize]
        [HttpPatch]
        public async Task<IActionResult> EditCategory(EditCategoryViewModel model)
        {
            if (!await _categoryService.EditCategory(model, _userId))
            {
                return NotFound();
            }

            return NoContent();
        }
    }
}

3、文章Controller

1、这里我在操作时遇到了文章内容乱码的问题，可能是因为数据库的text格式和输入格式有冲突，所以这里我暂时将其改成了nvarchar(max)的类型

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace BlogSystem.Model
{
    /// <summary>
    /// 文章
    /// </summary>
    public class Article : BaseEntity
    {
        /// <summary>
        /// 文章标题
        /// </summary>
        [Required]
        public string Title { get; set; }
        /// <summary>
        /// 文章内容
        /// </summary>
        [Required]
        public string Content { get; set; }
        /// <summary>
        /// 发表人的Id，用户表的外键
        /// </summary>
        [ForeignKey(nameof(User))]
        public Guid UserId { get; set; }
        public User User { get; set; }
        /// <summary>
        /// 看好人数
        /// </summary>
        public int GoodCount { get; set; }
        /// <summary>
        /// 不看好人数
        /// </summary>
        public int BadCount { get; set; }
        /// <summary>
        /// 文章查看所需等级
        /// </summary>
        public Level Level { get; set; } = Level.普通用户;
    }
}

ViewModel调整如下:

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 创建文章
    /// </summary>
    public class CreateArticleViewModel
    {
        /// <summary>
        /// 文章标题
        /// </summary>
        [Required]
        public string Title { get; set; }

        /// <summary>
        /// 文章内容
        /// </summary>
        [Required]
        public string Content { get; set; }

        /// <summary>
        /// 文章分类
        /// </summary>
        [Required]
        public List<Guid> CategoryIds { get; set; }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 编辑文章
    /// </summary>
    public class EditArticleViewModel
    {
        /// <summary>
        /// 文章Id
        /// </summary>
        public Guid Id { get; set; }

        /// <summary>
        /// 文章标题
        /// </summary>
        [Required]
        public string Title { get; set; }

        /// <summary>
        /// 文章内容
        /// </summary>
        [Required]
        public string Content { get; set; }

        /// <summary>
        /// 文章分类
        /// </summary>
        public List<Guid> CategoryIds { get; set; }
    }
}

using System;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 文章列表
    /// </summary>
    public class ArticleListViewModel
    {
        /// <summary>
        /// 文章Id
        /// </summary>
        public Guid ArticleId { get; set; }

        /// <summary>
        /// 文章标题
        /// </summary>
        public string Title { get; set; }

        /// <summary>
        /// 文章内容
        /// </summary>
        public string Content { get; set; }

        /// <summary>
        /// 创建时间
        /// </summary>
        public DateTime CreateTime { get; set; }

        /// <summary>
        /// 账号
        /// </summary>
        public string Account { get; set; }

        /// <summary>
        /// 头像
        /// </summary>
        public string ProfilePhoto { get; set; }

    }
}

using System;
using System.Collections.Generic;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 文章详情
    /// </summary>
    public class ArticleDetailsViewModel
    {
        /// <summary>
        /// 文章Id
        /// </summary>
        public Guid Id { get; set; }

        /// <summary>
        /// 文章标题
        /// </summary>
        public string Title { get; set; }

        /// <summary>
        /// 文章内容
        /// </summary>
        public string Content { get; set; }

        /// <summary>
        /// 创建时间
        /// </summary>
        public DateTime CreateTime { get; set; }

        /// <summary>
        /// 作者
        /// </summary>
        public string Account { get; set; }

        /// <summary>
        /// 头像
        /// </summary>
        public string ProfilePhoto { get; set; }

        /// <summary>
        /// 分类Id
        /// </summary>
        public List<Guid> CategoryIds { get; set; }

        /// <summary>
        /// 分类名称
        /// </summary>
        public List<string> CategoryNames { get; set; }

        /// <summary>
        /// 看好人数
        /// </summary>
        public int GoodCount { get; set; }
        /// <summary>
        /// 不看好人数
        /// </summary>
        public int BadCount { get; set; }

    }
}

2、调整IBLL和BLL内容，如下

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using BlogSystem.Model;
using BlogSystem.Model.ViewModels;

namespace BlogSystem.IBLL
{
    /// <summary>
    /// 文章接口
    /// </summary>
    public interface IArticleService : IBaseService<Article>
    {
        /// <summary>
        /// 新增文章
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<Guid> CreateArticleAsync(CreateArticleViewModel model, Guid userId);

        /// <summary>
        /// 编辑文章
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<bool> EditArticleAsync(EditArticleViewModel model, Guid userId);

        /// <summary>
        /// 通过Id获取文章详情
        /// </summary>
        /// <param name="articleId"></param>
        /// <returns></returns>
        Task<ArticleDetailsViewModel> GetArticleDetailsByArticleIdAsync(Guid articleId);

        /// <summary>
        /// 通过用户Id获取文章列表
        /// </summary>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<List<ArticleListViewModel>> GetArticlesByUserIdAsync(Guid userId);

        /// <summary>
        /// 通过用户分类Id获取所有文章
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="categoryId"></param>
        /// <returns></returns>
        Task<List<ArticleListViewModel>> GetArticlesByCategoryIdAsync(Guid userId, Guid categoryId);

        /// <summary>
        /// 通过用户Id获取文章数量
        /// </summary>
        /// <param name="userid"></param>
        /// <returns></returns>
        Task<int> GetArticleCountByUserIdAsync(Guid userid);

        /// <summary>
        /// 点赞文章
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task AddGoodCount(Guid articleId, Guid userId);

        /// <summary>
        /// 点灭文章
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task AddBadCount(Guid articleId, Guid userId);

        /// <summary>
        /// 删除文章所属分类信息
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task<bool> RemoveArticleInCategory(Guid articleId, Guid userId);

        /// <summary>
        /// 新增文章所属分类信息
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="categoryIds"></param>
        /// <returns></returns>
        Task CreateArticleInCategory(Guid articleId, List<Guid> categoryIds);
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using BlogSystem.IBLL;
using BlogSystem.IDAL;
using BlogSystem.Model;
using BlogSystem.Model.ViewModels;
using Microsoft.EntityFrameworkCore;

namespace BlogSystem.BLL
{
    /// <summary>
    /// 实现文章接口方法
    /// </summary>
    public class ArticleService : BaseService<Article>, IArticleService
    {
        private readonly IArticleRepository _articleRepository;
        private readonly IArticleInCategoryRepository _articleInCategoryRepository;
        private readonly ICategoryRepository _categoryRepository;
        private readonly IUserRepository _userRepository;

        //构造函数注入相关接口
        public ArticleService(IArticleRepository articleRepository, IArticleInCategoryRepository articleInCategoryRepository,
        ICategoryRepository categoryRepository, IUserRepository userRepository)
        {
            _articleRepository = articleRepository;
            BaseRepository = articleRepository;
            _articleInCategoryRepository = articleInCategoryRepository;
            _categoryRepository = categoryRepository;
            _userRepository = userRepository;
        }

        /// <summary>
        /// 创建文章
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<Guid> CreateArticleAsync(CreateArticleViewModel model, Guid userId)
        {
            //新增文章
            var articleId = Guid.NewGuid();
            var article = new Article
            {
                Id = articleId,
                UserId = userId,
                Title = model.Title,
                Content = model.Content
            };
            await _articleRepository.CreateAsync(article);

            //新增文章所属分类
            await CreateArticleInCategory(article.Id, model.CategoryIds);

            return articleId;
        }

        /// <summary>
        /// 编辑文章
        /// </summary>
        /// <param name="model"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<bool> EditArticleAsync(EditArticleViewModel model, Guid userId)
        {
            //删除文章所属分类
            if (!await RemoveArticleInCategory(model.Id, userId))
            {
                return false;
            }

            //新增文章所属分类
            await CreateArticleInCategory(model.Id, model.CategoryIds);

            //保存文章更新
            var article = await _articleRepository.GetOneByIdAsync(model.Id);
            article.Title = model.Title;
            article.Content = model.Content;
            await _articleRepository.EditAsync(article);

            return true;
        }

        /// <summary>
        /// 通过文章Id获取文章详情
        /// </summary>
        /// <param name="articleId"></param>
        /// <returns></returns>
        public async Task<ArticleDetailsViewModel> GetArticleDetailsByArticleIdAsync(Guid articleId)
        {
            if (!await _articleRepository.GetAll().AnyAsync(m => m.Id == articleId))
            {
                return new ArticleDetailsViewModel();
            }
            var data = await _articleRepository.GetAll().Include(m => m.User).Where(m => m.Id == articleId)
                .Select(m => new ArticleDetailsViewModel
                {
                    Id = m.Id,
                    Title = m.Title,
                    Content = m.Content,
                    CreateTime = m.CreateTime,
                    Account = m.User.Account,
                    ProfilePhoto = m.User.ProfilePhoto,
                    GoodCount = m.GoodCount,
                    BadCount = m.BadCount
                }).FirstAsync();
            //处理分类
            var categories = await _articleInCategoryRepository.GetAll().Include(m => m.Category)
                .Where(m => m.ArticleId == data.Id).ToListAsync();
            data.CategoryIds = categories.Select(m => m.CategoryId).ToList();
            data.CategoryNames = categories.Select(m => m.Category.CategoryName).ToList();
            return data;
        }

        /// <summary>
        /// 根据用户Id获取文章列表信息
        /// </summary>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<List<ArticleListViewModel>> GetArticlesByUserIdAsync(Guid userId)
        {
            if (!await _articleRepository.GetAll().AnyAsync(m => m.UserId == userId))
            {
                return new List<ArticleListViewModel>();
            }
            return await _articleRepository.GetAllByOrder(false).Include(m => m.User)
                .Where(m => m.UserId == userId).Select(m => new ArticleListViewModel
                {
                    ArticleId = m.Id,
                    Title = m.Title,
                    Content = m.Content,
                    CreateTime = m.CreateTime,
                    Account = m.User.Account,
                    ProfilePhoto = m.User.ProfilePhoto
                }).ToListAsync();
        }

        /// <summary>
        /// 通过用户分类Id获取文章列表
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="categoryId"></param>
        /// <returns></returns>
        public async Task<List<ArticleListViewModel>> GetArticlesByCategoryIdAsync(Guid userId, Guid categoryId)
        {
            //判断有无用户及分类信息
            if (!await _categoryRepository.GetAll().AnyAsync(m => m.UserId == userId && m.Id == categoryId))
            {
                return new List<ArticleListViewModel>();
            }

            var user = await _userRepository.GetOneByIdAsync(userId);

            return await _articleInCategoryRepository.GetAll().Include(m => m.Article)
                .Where(m => m.CategoryId == categoryId).Select(m => new ArticleListViewModel
                {
                    ArticleId = m.Id,
                    Title = m.Article.Title,
                    Content = m.Article.Content,
                    CreateTime = m.CreateTime,
                    Account = user.Account,
                    ProfilePhoto = user.ProfilePhoto
                }).ToListAsync();
        }

        /// <summary>
        /// 获取用户文章数量
        /// </summary>
        /// <param name="userid"></param>
        /// <returns></returns>
        public async Task<int> GetArticleCountByUserIdAsync(Guid userid)
        {
            return await _articleRepository.GetAll().CountAsync(m => m.UserId == userid);
        }

        /// <summary>
        /// 看好数量+1
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task AddGoodCount(Guid articleId, Guid userId)
        {
            var article = await _articleRepository.GetOneByIdAsync(articleId);
            article.GoodCount++;
            await _articleRepository.EditAsync(article);
        }

        /// <summary>
        /// 不看好数量+1
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task AddBadCount(Guid articleId, Guid userId)
        {
            var article = await _articleRepository.GetOneByIdAsync(articleId);
            article.BadCount++;
            await _articleRepository.EditAsync(article);
        }

        /// <summary>
        ///  删除文章所属分类信息
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task<bool> RemoveArticleInCategory(Guid articleId, Guid userId)
        {
            //判断是否为该用户文章
            if (!await _articleRepository.GetAll().AnyAsync(m => m.UserId == userId && m.Id == articleId))
            {
                return false;
            }
            //删除文章所属分类信息
            var categoryIds = _articleInCategoryRepository.GetAll().Where(m => m.ArticleId == articleId);
            foreach (var categoryId in categoryIds)
            {
                await _articleInCategoryRepository.RemoveAsync(categoryId, false);
            }
            await _articleInCategoryRepository.SavedAsync();
            return true;
        }

        /// <summary>
        /// 新增文章所属分类信息
        /// </summary>
        /// <param name="articleId"></param>
        /// <param name="categoryIds"></param>
        /// <returns></returns>
        public async Task CreateArticleInCategory(Guid articleId, List<Guid> categoryIds)
        {
            foreach (var categoryId in categoryIds)
            {
                await _articleInCategoryRepository.CreateAsync(new ArticleInCategory()
                {
                    ArticleId = articleId,
                    CategoryId = categoryId
                }, false);
            }
            await _articleInCategoryRepository.SavedAsync();
        }
    }
}

3、调整Controller如下：

using BlogSystem.Core.Helpers;
using BlogSystem.IBLL;
using BlogSystem.Model.ViewModels;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Threading.Tasks;

namespace BlogSystem.Core.Controllers
{
    [ApiController]
    [Route("api/article")]
    public class ArticleController : ControllerBase
    {
        private readonly IArticleService _articleService;
        private readonly Guid _userId;

        public ArticleController(IArticleService articleService, IHttpContextAccessor httpContext)
        {
            _articleService = articleService ?? throw new ArgumentNullException(nameof(articleService));
            var accessor = httpContext ?? throw new ArgumentNullException(nameof(httpContext));
            _userId = JwtHelper.JwtDecrypt(accessor.HttpContext.Request.Headers["Authorization"]).UserId;
        }

        /// <summary>
        /// 创建文章
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        [Authorize]
        [HttpPost]
        public async Task<IActionResult> CreateArticle(CreateArticleViewModel model)
        {

            var articleId = await _articleService.CreateArticleAsync(model, _userId);
            return CreatedAtRoute(nameof(GetArticleByArticleId), new { articleId }, model);
        }

        /// <summary>
        /// 编辑文章
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        [Authorize]
        [HttpPatch]
        public async Task<IActionResult> EditArticle(EditArticleViewModel model)
        {
            if (!await _articleService.EditArticleAsync(model, _userId))
            {
                return NotFound();
            }
            return NoContent();
        }

        /// <summary>
        /// 删除文章
        /// </summary>
        /// <param name="articleId"></param>
        /// <returns></returns>
        [Authorize]
        [HttpDelete("{articleId}")]
        public async Task<IActionResult> RemoveArticle(Guid articleId)
        {
            //删除文章所属分类
            if (!await _articleService.RemoveArticleInCategory(articleId, _userId))
            {
                return NotFound();
            }
            //删除文章
            await _articleService.RemoveAsync(articleId);
            return NoContent();
        }

        /// <summary>
        /// 通过文章Id获取文章详情
        /// </summary>
        /// <param name="articleId"></param>
        /// <returns></returns>
        [HttpGet("{articleId}", Name = nameof(GetArticleByArticleId))]
        public async Task<IActionResult> GetArticleByArticleId(Guid articleId)
        {
            var article = await _articleService.GetArticleDetailsByArticleIdAsync(articleId);
            if (article.Id == Guid.Empty)
            {
                return NotFound();
            }
            return Ok(article);
        }

        /// <summary>
        /// 通过用户Id获取文章列表
        /// </summary>
        /// <param name="userId"></param>
        /// <returns></returns>
        [HttpGet("list/{userId}")]
        public async Task<IActionResult> GetArticlesByUserId(Guid userId)
        {
            var list = await _articleService.GetArticlesByUserIdAsync(userId);
            return Ok(list);
        }

        /// <summary>
        /// 通过用户分类Id获取文章列表
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="categoryId"></param>
        /// <returns></returns>
        [HttpGet("list/{userId}/{categoryId}")]
        public async Task<IActionResult> GetArticlesByCategoryId(Guid userId, Guid categoryId)
        {
            var list = await _articleService.GetArticlesByCategoryIdAsync(userId, categoryId);
            return Ok(list);
        }
    }
}

4、评论Controller

1、这里发现评论回复表CommentReply设计存在问题，因为回复也有可能是针对回复型评论的，所以调整之后需要使用EF的迁移命令更行数据库，如下：

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace BlogSystem.Model
{
    /// <summary>
    /// 评论回复表
    /// </summary>
    public class CommentReply : BaseEntity
    {
        /// <summary>
        /// 回复指向的评论Id
        /// </summary>
        public Guid CommentId { get; set; }
        /// <summary>
        /// 回复指向的用户Id
        /// </summary>
        [ForeignKey(nameof(ToUser))]
        public Guid ToUserId { get; set; }
        public User ToUser { get; set; }
        /// <summary>
        /// 文章ID
        /// </summary>
        [ForeignKey(nameof(Article))]
        public Guid ArticleId { get; set; }
        public Article Article { get; set; }
        /// <summary>
        /// 用户Id
        /// </summary>
        [ForeignKey(nameof(User))]
        public Guid UserId { get; set; }
        public User User { get; set; }
        /// <summary>
        /// 回复的内容
        /// </summary>
        [Required, StringLength(800)]
        public string Content { get; set; }
    }
}

调整ViewModel如下，有人发现评论和回复的ViewModel相同，为什么不使用一个？是为了应对后续两张表栏位不同时，需要调整的情况

using System;
using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 文章评论
    /// </summary>
    public class CreateCommentViewModel
    {
        /// <summary>
        /// 评论内容
        /// </summary>
        [Required, StringLength(800)]
        public string Content { get; set; }
    }
}

using System.ComponentModel.DataAnnotations;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 添加回复型评论
    /// </summary>
    public class CreateApplyCommentViewModel
    {
        /// <summary>
        /// 回复的内容
        /// </summary>
        [Required, StringLength(800)]
        public string Content { get; set; }
    }
}

using System;

namespace BlogSystem.Model.ViewModels
{
    /// <summary>
    /// 文章评论列表
    /// </summary>
    public class CommentListViewModel
    {
        /// <summary>
        /// 文章Id
        /// </summary>
        public Guid ArticleId { get; set; }

        /// <summary>
        /// 用户Id
        /// </summary>
        public Guid UserId { get; set; }

        /// <summary>
        /// 账号
        /// </summary>
        public string Account { get; set; }

        /// <summary>
        /// 头像
        /// </summary>
        public string ProfilePhoto { get; set; }

        /// <summary>
        /// 评论Id
        /// </summary>
        public Guid CommentId { get; set; }

        /// <summary>
        /// 评论内容
        /// </summary>
        public string CommentContent { get; set; }

        /// <summary>
        /// 创建时间
        /// </summary>
        public DateTime CreateTime { get; set; }

    }
}

2、调整IBLL和BLL如下：

using BlogSystem.Model;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using BlogSystem.Model.ViewModels;

namespace BlogSystem.IBLL
{
    /// <summary>
    /// 评论服务接口
    /// </summary>
    public interface ICommentService : IBaseService<ArticleComment>
    {
        /// <summary>
        /// 添加评论
        /// </summary>
        /// <param name="model"></param>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task CreateComment(CreateCommentViewModel model, Guid articleId, Guid userId);

        /// <summary>
        /// 添加普通评论的回复
        /// </summary>
        /// <param name="model"></param>
        /// <param name="articleId"></param>
        /// <param name="commentId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task CreateReplyComment(CreateApplyCommentViewModel model, Guid articleId, Guid commentId, Guid userId);

        /// <summary>
        /// 添加回复评论的回复
        /// </summary>
        /// <param name="model"></param>
        /// <param name="articleId"></param>
        /// <param name="commentId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        Task CreateToReplyComment(CreateApplyCommentViewModel model, Guid articleId, Guid commentId, Guid userId);

        /// <summary>
        /// 通过文章Id获取所有评论
        /// </summary>
        /// <param name="articleId"></param>
        /// <returns></returns>
        Task<List<CommentListViewModel>> GetCommentsByArticleIdAsync(Guid articleId);

        /// <summary>
        /// 确认回复型评论是否存在
        /// </summary>
        /// <param name="commentId"></param>
        /// <returns></returns>
        Task<bool> ReplyExistAsync(Guid commentId);
    }
}

using BlogSystem.IBLL;
using BlogSystem.IDAL;
using BlogSystem.Model;
using BlogSystem.Model.ViewModels;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace BlogSystem.BLL
{
    public class CommentService : BaseService<ArticleComment>, ICommentService
    {
        private readonly IArticleCommentRepository _commentRepository;
        private readonly ICommentReplyRepository _commentReplyRepository;

        public CommentService(IArticleCommentRepository commentRepository, ICommentReplyRepository commentReplyRepository)
        {
            _commentRepository = commentRepository;
            BaseRepository = commentRepository;
            _commentReplyRepository = commentReplyRepository;
        }

        /// <summary>
        /// 添加评论
        /// </summary>
        /// <param name="model"></param>
        /// <param name="articleId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task CreateComment(CreateCommentViewModel model, Guid articleId, Guid userId)
        {
            await _commentRepository.CreateAsync(new ArticleComment()
            {
                ArticleId = articleId,
                Content = model.Content,
                UserId = userId
            });
        }

        /// <summary>
        ///  添加普通评论的回复
        /// </summary>
        /// <param name="model"></param>
        /// <param name="articleId"></param>
        /// <param name="commentId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task CreateReplyComment(CreateApplyCommentViewModel model, Guid articleId, Guid commentId, Guid userId)
        {
            var comment = await _commentRepository.GetOneByIdAsync(commentId);
            var toUserId = comment.UserId;

            await _commentReplyRepository.CreateAsync(new CommentReply()
            {
                CommentId = commentId,
                ToUserId = toUserId,
                ArticleId = articleId,
                UserId = userId,
                Content = model.Content
            });
        }

        /// <summary>
        /// 添加回复型评论的回复
        /// </summary>
        /// <param name="model"></param>
        /// <param name="articleId"></param>
        /// <param name="commentId"></param>
        /// <param name="userId"></param>
        /// <returns></returns>
        public async Task CreateToReplyComment(CreateApplyCommentViewModel model, Guid articleId, Guid commentId, Guid userId)
        {
            var comment = await _commentReplyRepository.GetOneByIdAsync(commentId);
            var toUserId = comment.UserId;

            await _commentReplyRepository.CreateAsync(new CommentReply()
            {
                CommentId = commentId,
                ToUserId = toUserId,
                ArticleId = articleId,
                UserId = userId,
                Content = model.Content
            });
        }

        /// <summary>
        /// 根据文章Id获取评论信息
        /// </summary>
        /// <param name="articleId"></param>
        /// <returns></returns>
        public async Task<List<CommentListViewModel>> GetCommentsByArticleIdAsync(Guid articleId)
        {
            //正常评论
            var comment = await _commentRepository.GetAll().Where(m => m.ArticleId == articleId)
                .Include(m => m.User).Select(m => new CommentListViewModel
                {
                    ArticleId = m.ArticleId,
                    UserId = m.UserId,
                    Account = m.User.Account,
                    ProfilePhoto = m.User.ProfilePhoto,
                    CommentId = m.Id,
                    CommentContent = m.Content,
                    CreateTime = m.CreateTime
                }).ToListAsync();

            //回复型的评论
            var replyComment = await _commentReplyRepository.GetAll().Where(m => m.ArticleId == articleId)
                .Include(m => m.User).Select(m => new CommentListViewModel
                {
                    ArticleId = m.ArticleId,
                    UserId = m.UserId,
                    Account = m.User.Account,
                    ProfilePhoto = m.User.ProfilePhoto,
                    CommentId = m.Id,
                    CommentContent = $"@{m.ToUser.Account}" + Environment.NewLine + m.Content,
                    CreateTime = m.CreateTime
                }).ToListAsync();

            var list = comment.Union(replyComment).OrderByDescending(m => m.CreateTime).ToList();
            return list;
        }

        /// <summary>
        /// 确认回复型评论是否存在
        /// </summary>
        /// <param name="commentId"></param>
        /// <returns></returns>
        public async Task<bool> ReplyExistAsync(Guid commentId)
        {
            return await _commentReplyRepository.GetAll().AnyAsync(m => m.Id == commentId);
        }
    }
}