Question

编辑：我已经解决了原来的问题，但它引发了另一个问题

问题在于这一行

&& (logLevel == "All" || logLevel == "Error")

'list'中的LINQ查询生成以下SQL

SELECT 
0 AS [C1], 
N'guid' AS [C2], 
[Extent1].[ErrorId] AS [ErrorId], 
[Extent1].[TimeUtc] AS [TimeUtc]
FROM [ELMAH_Error] AS [Extent1]
WHERE ([Extent1].[TimeUtc] >= @p__linq__0) AND ([Extent1].[TimeUtc] <= @p__linq__1) AND ((N'All' = @p__linq__2) OR (N'Error' = @p__linq__3))

我得到的错误（内部异常=“p_linq_2：字符串截断：max = 3，len = 5，value ='错误'。”）是由SQL的这一部分引起的

(N'All' = @p__linq__2)

当我从LINQ查询中删除logLevel ==“All”时，错误消失了。

所以，我现在的问题是 - 为什么LINQ / SQL试图截断p_linq__2？它正在进行比较......为什么需要截断？

原始问题

我正在将Elmah和Log4Net与我现有的MVC应用程序集成（遵循本指南 - http://www.codeproject.com/Articles/104112/Log-Reporting-Dashboard-for-ASP-NET-MVC）。我正在使用SQL CE 4.已处理和未处理的错误正在记录到数据库中，我遇到的问题是使用UI来查看错误

我收到此行触发的EntityCommandExecutionException（下面的完整方法列表）

return new PagedList<LogEvent>(list, pageIndex, pageSize);

错误消息=“执行命令时发生错误定义。有关详细信息，请参阅内部异常。“
内部异常=“p_ linq _2：字符串截断：max = 3，len = 5，value ='错误'。”

从我所看到的，'list'填充OK ..

发生错误的方法

public IPagedList<LogEvent> GetByDateRangeAndType(int pageIndex, int pageSize, DateTime start, DateTime end, string logProviderName, string logLevel)
    {
        IQueryable<LogEvent> list = null;

        switch (logProviderName)
        {
            case "All":
                foreach (string providerName in logProviders.Keys)
                {
                    IQueryable<LogEvent> logList = GetProvider(providerName).GetByDateRangeAndType(pageIndex, pageSize, start, end, logLevel);
                    list = (list == null) ? logList : list.Union(logList);
                }
                break;

            default:
                list = GetProvider(logProviderName).GetByDateRangeAndType(pageIndex, pageSize, start, end, logLevel);
                break;
        }

        list = list.OrderByDescending(d => d.LogDate);

        return new PagedList<LogEvent>(list, pageIndex, pageSize);
    }

它调用的方法

private ILogReportingRepository GetProvider(string logProviderName)
    {
        string logSourceType = logProviders[logProviderName];

        Type providerType = Type.GetType(logSourceType);

        ILogReportingRepository provider = Activator.CreateInstance(providerType, _context) as ILogReportingRepository;

        return provider;
    }

链式方法

public IQueryable<LogEvent> GetByDateRangeAndType(int pageIndex, int pageSize, DateTime start, DateTime end, string logLevel)
    {
        IQueryable<LogEvent> list = (from a in _context.ELMAH_Error
                                     where a.TimeUtc >= start && a.TimeUtc <= end
                                     && (logLevel == "All" || logLevel == "Error")
                                     select new LogEvent
                                     {
                                         IdType = "guid"
                                       ,
                                         Id = ""
                                       ,
                                         IdAsInteger = 0
                                       ,
                                         IdAsGuid = a.ErrorId
                                       ,
                                         LoggerProviderName = "Elmah"
                                       ,
                                         LogDate = a.TimeUtc
                                       ,
                                         MachineName = a.Host
                                       ,
                                         Message = a.Message
                                       ,
                                         Type = a.Type
                                       ,
                                         Level = "Error"
                                       ,
                                         Source = a.Source,
                                         StackTrace = ""
                                     });

        return list;
    }

堆栈跟踪

[InvalidOperationException：p_ linq _2：字符串截断：max = 3，len = 5，value ='Error'。] System.Data.SqlServerCe.SqlCeCommand.FillParameterDataBindings（Boolean verifyValue）+1670 System.Data.SqlServerCe.SqlCeCommand.ExecuteCommand（CommandBehavior behavior，String method，ResultSetOptions options）+397 System.Data.SqlServerCe.SqlCeCommand.ExecuteReader（CommandBehavior behavior）+59 System.Data.SqlServerCe.SqlCeMultiCommand.ExecuteReader（CommandBehavior behavior）+342 System.Data.SqlServerCe.SqlCeMultiCommand.ExecuteDbDataReader（CommandBehavior behavior）+41 System.Data.Common.DbCommand.ExecuteReader（CommandBehavior behavior）+10 System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands（EntityCommand entityCommand，CommandBehavior behavior）+437

[EntityCommandExecutionException：执行命令定义时发生错误。有关详细信息，请参阅内部异常。] System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands（EntityCommand entityCommand，CommandBehavior behavior）+507 System.Data.Objects.Internal.ObjectQueryExecutionPlan.Execute（ObjectContext context，ObjectParameterCollection parameterValues）+675 System.Data.Objects.ObjectQuery 1.GetResults(Nullable 1 forMergeOption）+102 System.Data.Objects.ObjectQuery 1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() +30 System.Linq.Enumerable.Single(IEnumerable 1 source）+100 System.Data.Objects.ELinq.ObjectQueryProvider.b__3（IEnumerable 1 sequence) +5 System.Data.Objects.ELinq.ObjectQueryProvider.ExecuteSingle(IEnumerable 1个查询，表达式queryRoot）+25 System.Data.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute（Expression expression）+70 System.Data.Entity.Internal.Linq.DbQueryProvider.Execute（表达式表达式）+82 System.Linq.Queryable.Count（IQueryable 1 source) +233 MvcPaging.PagedList 1..ctor（IQueryable 1 source, Int32 index, Int32 pageSize, Nullable 1 totalCount）+532 IDSM.Repository.LogReportingFacade.GetByDateRangeAndType（Int32 pageIndex，Int32 pageSize，DateTime start，DateTime end，

Answer 1

我已经解决了我的问题，虽然它引出了另一个问题。

问题在于这一行

&& (logLevel == "All" || logLevel == "Error")

'list'中的LINQ查询生成以下SQL

SELECT 
0 AS [C1], 
N'guid' AS [C2], 
[Extent1].[ErrorId] AS [ErrorId], 
[Extent1].[TimeUtc] AS [TimeUtc]
FROM [ELMAH_Error] AS [Extent1]
WHERE ([Extent1].[TimeUtc] >= @p__linq__0) AND ([Extent1].[TimeUtc] <= @p__linq__1) AND ((N'All' = @p__linq__2) OR (N'Error' = @p__linq__3))

我得到的错误（内部异常=“p_linq_2：字符串截断：max = 3，len = 5，value ='错误'。”）是由SQL的这一部分引起的

(N'All' = @p__linq__2)

当我删除了LINQ查询中的logLevel ==“All”时，错误消失了。

我的下一个问题是 - 为什么LINQ / SQL试图截断p_linq__2？它正在进行比较......为什么需要截断？

返回PagedList时的EntityCommandExecutionException

1 个答案: