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[英]The instance of entity type 'TestType' cannot be tracked because another instance of this type with the same key is already being tracked
[英]EF: The instance of entity type X cannot be tracked because another instance of this type with the same key is already being tracked
我在我的http请求中以Json格式发送一个User实体,如下所示:
POST http://localhost:52054/api/Authentication/DeleteAccessToken HTTP/1.1
Host: localhost:52054
Content-Type: application/json
{"id":1,"userName":"mnoureldin","accessToken":{"id":1,"token":"123ABC456EFG","userId":1}}
我的控制器(在EF核心中 )处理如下:
[HttpPost]
public IActionResult DeleteAccessToken([FromBody]User user)
{
using (var Context = new UnitOfWork().Context)
{
var userEntity = Context.Users.Find(user.Id); // Get the real entity of the user received as json
if (userEntity != null)
{
var accessTokenEntity = Context.AccessTokens.Find(userEntity.AccessToken.Id); // Find the entity of the accesstoken (I tried also directly by accessing the navigation property of user entity)
Context.AccessTokens.Remove(accessTokenEntity);
return Ok();
}
else
{
return Unauthorized();
}
}
}
但行Context.AccessTokens.Remove(accessTokenEntity);
抛出此异常:
Microsoft.EntityFrameworkCore.dll中出现“System.InvalidOperationException”类型的异常,但未在用户代码中处理
附加信息:无法跟踪实体类型“AccessToken”的实例,因为已经跟踪了具有相同密钥的此类型的另一个实例。 添加新实体时,对于大多数键类型,如果未设置任何键,则将创建唯一的临时键值(即,如果为键属性指定了其类型的默认值)。 如果要为新实体显式设置键值,请确保它们不会与现有实体或为其他新实体生成的临时值发生冲突。 附加现有实体时,请确保只有一个具有给定键值的实体实例附加到上下文。
我还尝试直接从userEntity访问AccessToken导航属性,但具有相同的异常。
这是我的UnitOfWork初始化:
public UnitOfWork()
{
// Configure EF connection
var optionsBuilder = new DbContextOptionsBuilder<CustomDbContext>();
optionsBuilder
.UseMySQL(@"server=192.168.1.35; port=3306; sslmode=none;
userid=root;
pwd=P@ssword;
database=dotnet;");
Context = new CustomDbContext(optionsBuilder.Options);
// Configure data loading method to explicit
Context.AccessTokens.Load();
}
我的CustomBdContext:
public class CustomDbContext : DbContext
{
// Tell EF to map the entities to tables
public DbSet<User> Users { get; set; }
public DbSet<AccessToken> AccessTokens { get; set; }
public CustomDbContext(DbContextOptions options) : base(options)
{
}
}
我有以下简单的数据模型与一对一的关系:
User ----- AccessToken
用户:
public class User
{
public int Id { get; set; }
public string UserName { get; set; }
public virtual AccessToken AccessToken { get; set; }
}
的accessToken:
public class AccessToken
{
public int Id { get; set; }
public string Token { get; set; }
[ForeignKey("User"), Required]
public int UserId { get; set; }
public virtual User User { get; set; }
}
有人可以帮我解决这个问题吗? 我不明白到底发生了什么......
看来EF已经在跟踪user
和其中的AccessToken
。 因此,让我们尝试避免获取同一实体的另一个实例并重用已经跟踪过的实例。
尝试
[HttpPost]
public IActionResult DeleteAccessToken([FromBody]User user)
{
// Requires System.Linq
if (Context.Users.Any(u => u.Id == user.Id))
{
var accessTokenEntity = Context.AccessTokens.Find(user.AccessToken.Id); // Find the entity of the accesstoken (I tried also directly by accessing the navigation property of user entity)
Context.AccessTokens.Remove(accessTokenEntity);
// NOTE: You re not saving?
return Ok();
}
else
{
return Unauthorized();
}
}
或者尝试:
[HttpPost]
public IActionResult DeleteAccessToken([FromBody]User user)
{
if (Context.Users.Any(u => u.Id == user.Id))
{
Context.AccessTokens.Remove(user.AccessToken);
return Ok();
}
else
{
return Unauthorized();
}
}
尝试替换此行:
var accessTokenEntity = Context.AccessTokens.Find(userEntity.AccessToken.Id);
至:
var accessTokenEntity = Context.AccessTokens.AsNoTracking().Find(userEntity.AccessToken.Id);
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