c# - Entity Framework 核心 3.1.7 : failure during Update of record

Question

我有一个最简单的 ASP.NET Core 3.1 Web API 解决方案，其中一个模型项目使用 Entity Framework Core 3.1.7 将我的模型映射到 SQL Server。

我有以下实体:

[Table("SessionDetails")]
public class SessionDetailsModel
{
    public long Id { get; set; }
    public DateTime CreateDate { get; set; }
    public Guid Token { get; set; }
    public bool IsValid { get; set; }
}

每次用户调用登录端点 (POST) 时创建。

数据库上下文配置如下:

public class RunMeDbContext : DbContext
{
    public RunMeDbContext(DbContextOptions<RunMeDbContext> options) : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<SessionDetailsModel>()
            .HasKey(x => new {x.Id, x.CreateDate});

        base.OnModelCreating(modelBuilder);
    }

    public DbSet<SessionDetailsModel> SessionDetails { get; set; }
}

插入成功，但是当我调用注销端点时，它通过 token 字段获取先前创建的 SessionDetails 记录，并尝试将“IsValid”字段(bool)从 true 更新为false，我得到以下异常:

Microsoft.EntityFrameworkCore.DbUpdateConcurrencyException: Database operation expected to affect 1 row(s) but actually affected 0 row(s). Data may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=527962 for information on understanding and handling optimistic concurrency exceptions.

我是唯一连接到数据库的人，在阅读并发冲突后，我可以保证没有对记录进行其他更改。

我的代码:

    public async Task<bool> InvalidateSession(Guid token)
    {
        var session = await _dbContext.SessionDetails.FirstOrDefaultAsync(sd => sd.Token.Equals(token))
            .ConfigureAwait(false);

        if (session == null)
            return false;

        session.IsValid = false;
        
        _dbContext.Update(session);
        await _dbContext.SaveChangesAsync().ConfigureAwait(false);

        return true;
    }

提示:在调试时我注意到虽然我正在更改的唯一字段是“IsValid = false”，但由于某些奇怪的原因，Token 字段也被修改了(尽管它的值是相同的):

正如您在此屏幕截图中所见:

Answer 1

我无法重现此行为。看看您是否可以修改它以展示您正在观察的行为。

using Microsoft.Data.SqlClient;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using System;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;

namespace EfCore3Test
{

    [Table("SessionDetails")]
    public class SessionDetailsModel
    {
        public long Id { get; set; }
        public DateTime CreateDate { get; set; }
        public Guid Token { get; set; }
        public bool IsValid { get; set; }
    }
    public class Db : DbContext
    {
           
        public Db(): base()
        {

        }

        private static readonly ILoggerFactory loggerFactory = LoggerFactory.Create(builder =>
        {
            builder.AddFilter((category, level) =>
               category == DbLoggerCategory.Database.Command.Name
               && level == LogLevel.Information).AddConsole();
        });


        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            var constr = "Server = localhost; database = efcore3test; integrated security = true";

            optionsBuilder.UseLoggerFactory(loggerFactory)
                          .UseSqlServer(constr, o => o.UseRelationalNulls());

            //optionsBuilder.UseLazyLoadingProxies();
            base.OnConfiguring(optionsBuilder);
        }

        public DbSet<SessionDetailsModel> SessionDetails { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<SessionDetailsModel>()
              .HasKey(x => new { x.Id, x.CreateDate });

            modelBuilder.Entity<SessionDetailsModel>().Property(e => e.Id).UseIdentityColumn();

            modelBuilder.Entity<SessionDetailsModel>().HasIndex(e => e.Token).IsUnique(true);

            base.OnModelCreating(modelBuilder);            
        }
    }


    class Program
    {
        static void Main(string[] args)
        {

            long id;
            DateTime created = DateTime.Now;
            Guid token = Guid.NewGuid();
            
            using (var db = new Db())
            {

                db.Database.EnsureDeleted();
                db.Database.EnsureCreated();

                var s = new SessionDetailsModel();
                s.CreateDate = created;
                s.Token = token;
                s.IsValid = true;
                db.SessionDetails.Add(s);
                db.SaveChanges();
                id = s.Id;
            }
            using (var db = new Db())
            {
                var sd = db.SessionDetails.Where(d => d.Token == token).Single();
                sd.IsValid = false;
                db.SaveChanges();
            }
        }
    }

}