EF Core：在Shadow Properties中获取经过身份验证的用户名

Question

作为记录谁输入/更新数据的记录的一部分，我在所有实体中添加了4个公共字段（“创建者”，“创建日期”，“修改者”，“修改日期”）。为此，我正在使用多个论坛中建议的阴影属性功能，包括https://dotnetcore.gaprogman.com/2017/01/26/entity-framework-core-shadow-properties/

我的问题是如何获取有关经过身份验证的用户的信息？。如果是控制器，则可以访问ApplicationUserManager，但是在这种情况下，阴影属性位于

AppDbContext：IdentityDbContext 类。

这是一个asp.net core 2 Web API项目。

任何建议都将受到高度赞赏。谢谢

Answer 1

您可以使用来获取当前用户的名称HttpContext.User.Identity.Name。您可以访问HttpContextusing IHttpContextAccessor。此接口应该已经在服务集合中注册。否则，您可以注册它：

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
    services.AddDbContext<ApplicationDbContext>(options =>
         options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
    // ...
}

然后，您可以从以下位置使用此接口DbContext：

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    private readonly IHttpContextAccessor _httpContextAccessor;

    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options, IHttpContextAccessor httpContextAccessor)
        : base(options)
    {
        _httpContextAccessor = httpContextAccessor;
    }

    public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
    {
        var httpContext = _httpContextAccessor.HttpContext;
        if(httpContext != null)
        {
            var authenticatedUserName = httpContext.User.Identity.Name;

            // If it returns null, even when the user was authenticated, you may try to get the value of a specific claim 
            var authenticatedUserId = _httpContextAccessor.HttpContext.User.FindFirst(ClaimTypes.NameIdentifier).Value
            // var authenticatedUserId = _httpContextAccessor.HttpContext.User.FindFirst("sub").Value

            // TODO use name to set the shadow property value like in the following post: https://www.meziantou.net/2017/07/03/entity-framework-core-generate-tracking-columns
        }

        return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
    }
}