EF Core如何动态更新含无限嵌套关联的数据库实体？

数据库中包含role、user、company等大量实体，所有实体支持自引用形成树形结构，且实体间存在复杂关联。现有API端点接收与原数据库对象结构一致的JSON快照数据（包含嵌套对象的新增、删除、修改），需要动态更新用户实体，但希望避免编写完全自定义的实现。

尝试过以下方法均失败：

• 使用JsonConvert.PopulateObject，报错“Cannot track some objects”；
• 手动调用_context.TryAttach跟踪对象，导致provider对象被清空而非更新；
• 编写自定义ExtendedJsonConverter进行反序列化并自动附加对象，同样失败。

当前API端点及AuthFacade.Update方法代码如下：

API端点代码 #

[HttpPut]
[Route("UpdateSystemUser")]
public async Task<IActionResult> UpdateSystemUser(
    [Caller] SystemUser caller, [FromForm]int key, [FromForm]string values, CancellationToken cancellationToken)
{
    var user = 
        await _userManager.Users
            .Include(x => x.roles)
            .Include(x => x.companies)
            .Include(x => x.providers)
            .SingleOrDefaultAsync(x => x.Id == key, cancellationToken: cancellationToken);
    if (user == null)
    {
        return NotFound();
    }

    JsonConvert.PopulateObject(values, user, new JsonSerializerSettings()
    {
        ObjectCreationHandling = ObjectCreationHandling.Replace
    });


    await _authFacade.Update(caller, user, cancellationToken);
    
    var (systemUser, token) = 
        await _authFacade.GenerateActivationDataAsync(user);

    var result = JsonConvert.SerializeObject(systemUser, new JsonSerializerSettings
    {
        ContractResolver = 
            new ExtendedContractResolver(
                ignoredProperties: new Dictionary<Type, string[]>
                {
                    [typeof(SystemRole)] = new []{nameof(SystemRole.users)},
                    [typeof(Company)] = new []{nameof(Company.users), nameof(Company.parent)},
                    [typeof(Provider)] = new []{nameof(Provider.users)}
                })
    });

    return Ok(result);
}

AuthFacade.Update方法代码 #

public async Task<SystemUser> Update(SystemUser caller, SystemUser user, CancellationToken cancellationToken)
{
    var result = await _userManager.UpdateAsync(user);
    if (!result.Succeeded)
    {
        throw new Exception(result.Errors.Select(x => x.Description).Aggregate((i, j) => i + ", " + j));
    }
    return user;
}

寻求无需自定义复杂逻辑的统一解决方案，是否存在简洁的实现方式？

可以借助AutoMapper配合EF Core的实体跟踪机制实现，无需编写大量自定义逻辑：

1. 安装依赖包
   确保项目中安装AutoMapper和AutoMapper.Extensions.Microsoft.DependencyInjection NuGet包。

2. 配置AutoMapper映射规则
   创建映射配置，处理快照对象到已跟踪实体的属性映射，同时忽略反向导航属性避免循环引用和跟踪冲突：

   public class MappingProfile : Profile
   {
       public MappingProfile()
       {
           // 用户实体映射：忽略主键，映射嵌套集合
           CreateMap<SystemUser, SystemUser>()
               .ForMember(dest => dest.Id, opt => opt.Ignore())
               .ForMember(dest => dest.roles, opt => opt.MapFrom(src => src.roles))
               .ForMember(dest => dest.companies, opt => opt.MapFrom(src => src.companies))
               .ForMember(dest => dest.providers, opt => opt.MapFrom(src => src.providers));
   
           // 嵌套实体映射：忽略反向导航属性
           CreateMap<SystemRole, SystemRole>()
               .ForMember(dest => dest.users, opt => opt.Ignore());
           CreateMap<Company, Company>()
               .ForMember(dest => dest.users, opt => opt.Ignore())
               .ForMember(dest => dest.parent, opt => opt.Ignore());
           CreateMap<Provider, Provider>()
               .ForMember(dest => dest.users, opt => opt.Ignore());
       }
   }
   

3. 修改API端点逻辑
   先将JSON快照反序列化为独立对象，再用AutoMapper将快照数据映射到已跟踪的用户实体，最后保存变更：

   [HttpPut]
   [Route("UpdateSystemUser")]
   public async Task<IActionResult> UpdateSystemUser(
       [Caller] SystemUser caller, [FromForm]int key, [FromForm]string values, CancellationToken cancellationToken)
   {
       var existingUser = 
           await _userManager.Users
               .Include(x => x.roles)
               .Include(x => x.companies)
               .Include(x => x.providers)
               .SingleOrDefaultAsync(x => x.Id == key, cancellationToken: cancellationToken);
       if (existingUser == null)
       {
           return NotFound();
       }
   
       // 反序列化JSON为快照对象
       var userSnapshot = JsonConvert.DeserializeObject<SystemUser>(values, new JsonSerializerSettings
       {
           ObjectCreationHandling = ObjectCreationHandling.Replace
       });
   
       // 用AutoMapper将快照数据映射到已跟踪实体
       _mapper.Map(userSnapshot, existingUser);
   
       // 执行更新（EF Core自动跟踪实体变更）
       await _authFacade.Update(caller, existingUser, cancellationToken);
       
       var (systemUser, token) = 
           await _authFacade.GenerateActivationDataAsync(existingUser);
   
       var result = JsonConvert.SerializeObject(systemUser, new JsonSerializerSettings
       {
           ContractResolver = 
               new ExtendedContractResolver(
                   ignoredProperties: new Dictionary<Type, string[]>
                   {
                       [typeof(SystemRole)] = new []{nameof(SystemRole.users)},
                       [typeof(Company)] = new []{nameof(Company.users), nameof(Company.parent)},
                       [typeof(Provider)] = new []{nameof(Provider.users)}
                   })
       });
   
       return Ok(result);
   }
   

4. 优化AuthFacade.Update方法（可选）
   若UserManager.UpdateAsync无法处理嵌套实体变更，直接使用DbContext保存：

   public async Task<SystemUser> Update(SystemUser caller, SystemUser user, CancellationToken cancellationToken)
   {
       await _context.SaveChangesAsync(cancellationToken);
       return user;
   }
   

核心逻辑：AutoMapper自动处理属性和嵌套集合的映射，EF Core依赖对现有实体的跟踪识别变更，完全规避手动处理实体附加、跟踪冲突的复杂逻辑。

内容的提问来源于stack exchange，提问作者codeceptive solutions