There is already an open DataReader associated with this Connection which must be closed first

本文介绍了一个在MVC4中使用EF Linq进行foreach列表循环时遇到的报错问题:“There is already an open DataReader associated with this Connection which must be closed first”。通过简单修改将Model直接改为Model.ToList()解决了此问题。

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使用MVC4 EF Linq获取foreach列表循环的时候遇到了如下的问题:报错提示
There is already an open DataReader associated with this Connection which must be closed first

解决方法如下红色所示:
@foreach (var item in Model.ToList())
{
  @Html.ActionLink(@item.user.nickname + "(微信)", "../Mess/MessInfo", new { id = item.id })
}
将Model改成Model.ToList()的就ok了

 

转载于:https://www.cnblogs.com/hww9011/p/3611592.html

fail: 2023/7/14 14:31:33.417 CoreEventId.QueryIterationFailed[10100] (Microsoft.EntityFrameworkCore.Query) An exception occurred while iterating over the results of a query for context type 'iMES.Core.EFDbContext.SysDbContext'. System.InvalidOperationException: There is already an open DataReader associated with this Connection which must be closed first. at Microsoft.Data.SqlClient.SqlInternalConnectionTds.ValidateConnectionForExecute(SqlCommand command) at Microsoft.Data.SqlClient.SqlConnection.ValidateConnectionForExecute(String method, SqlCommand command) at Microsoft.Data.SqlClient.SqlCommand.ValidateCommand(Boolean isAsync, String method) at Microsoft.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry, String method) at Microsoft.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at Microsoft.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior) at Microsoft.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject) at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.InitializeReader(Enumerator enumerator) at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.<>c.<MoveNext>b__21_0(DbContext _, Enumerator enumerator) at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded) at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
07-15
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