Microsoft Identity Framework 将角色分配给 Postgres 数据库的用户错误 - CancellationTokenSource 已被释放

Question

您好，我在使用 Identity Framework 5.0.5、.net5.0.5 和 Postgres SQL db 为用户分配角色时遇到问题。

用于将角色分配给用户的代码如下所示，错误如下。

如果可能，请提供帮助。

非常感谢！

       {
           if (!await roleManager.RoleExistsAsync("Admin"))
           {
               await roleManager.CreateAsync(new IdentityRole
               {
                   Name = "Admin"
               });
           }
           
           ApplicationUser user = await userManager.FindByIdAsync(userId);
           if (isAdmin)
           {
               await userManager.AddToRoleAsync(user, "Admin");
           }
           else
           {
               await userManager.RemoveFromRoleAsync(user, "Admin");
           }
       }
   }


services.AddDbContext<ApplicationDbContext>(options =>
   options.UseNpgsql(
       Configuration.GetConnectionString("DefaultConnection"), 
       builder => builder.EnableRetryOnFailure(50, TimeSpan.FromSeconds(5), null)));

System.ObjectDisposedException: The CancellationTokenSource has been disposed.
   at System.Threading.CancellationTokenSource.ThrowObjectDisposedException()
   at System.Threading.CancellationTokenSource.CancelAfter(Int32 millisecondsDelay)
   at System.Threading.CancellationTokenSource.CancelAfter(TimeSpan delay)
   at Npgsql.Util.ResettableCancellationTokenSource.Stop()
   at Npgsql.NpgsqlReadBuffer.<Ensure>g__EnsureLong|40_0(NpgsqlReadBuffer buffer, Int32 count, Boolean async, Boolean readingNotifications)
   at Npgsql.NpgsqlConnector.<ReadMessage>g__ReadMessageLong|194_0(NpgsqlConnector connector, Boolean async, DataRowLoadingMode dataRowLoadingMode, Boolean readingNotifications, Boolean isReadingPrependedMessage)
   at Npgsql.NpgsqlDataReader.NextResult(Boolean async, Boolean isConsuming, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteReader(CommandBehavior behavior, Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteReader(CommandBehavior behavior, Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(DbContext _, Boolean result, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.ExecutionStrategy.ExecuteImplementationAsync[TState,TResult](Func`4 operation, Func`4 verifySucceeded, TState state, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.ExecutionStrategy.ExecuteImplementationAsync[TState,TResult](Func`4 operation, Func`4 verifySucceeded, TState state, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleOrDefaultAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleOrDefaultAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
   at SearchDataScreening.Pages.UserManagement.OnGetAdminControl(String userId, Boolean isAdmin) in /Users/dewaldthattingh/GitHubRepos/TPS/SearchScreening/SearchDataScreening/Pages/UserManagement.cshtml.cs:line 50
   at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__140_1(Object state)
   at System.Threading.QueueUserWorkItemCallback.<>c.<.cctor>b__6_0(QueueUserWorkItemCallback quwi)
   at System.Threading.ExecutionContext.RunForThreadPoolUnsafe[TState](ExecutionContext executionContext, Action`1 callback, TState& state)
   at System.Threading.QueueUserWorkItemCallback.Execute()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

Answer 1

请尝试将其更改为不使用下面的等待方法

  bool roleExist =  roleManager.RoleExistsAsync("Admin").Result;
        if (!roleExist)
        {
            var x =  roleManager.CreateAsync(new IdentityRole
            {
                Name = "Admin"
            }).Result;
        }

        if (isAdmin)
        {
            var user =  userManager.FindByIdAsync(userId).Result;
            if (user != null)
            {
                var x = userManager.AddToRoleAsync(user, "Admin").Result;
            }
        }
        else
        {
            var user =  userManager.FindByIdAsync(userId).Result;
            if (user != null)
            {
                var x = userManager.RemoveFromRoleAsync(user, "Admin").Result;
            }
        }