【发布时间】：2011-04-20 08:25:14
【问题描述】：
我使用的是 EF 4.0，它工作得非常好，但是出现了问题 我叫查询：
var query = from employee in employees
from cr in employee.RcpCrossRegister
select new { employee, cr }
然后当我打电话时
var list = query.ToList()
我遇到了异常
Collection was modified; enumeration operation may not execute
and call stack:
w System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
w System.Collections.Generic.List`1.Enumerator.MoveNextRare()
w System.Collections.Generic.List`1.Enumerator.MoveNext()
w System.Data.Objects.DataClasses.EntityCollection`1.CheckIfNavigationPropertyContainsEntity(IEntityWrapper wrapper)
w System.Data.Objects.DataClasses.RelatedEnd.Add(IEntityWrapper wrappedTarget, Boolean applyConstraints, Boolean addRelationshipAsUnchanged, Boolean relationshipAlreadyExists, Boolean allowModifyingOtherEndOfRelationship, Boolean forceForeignKeyChanges)
w System.Data.Objects.DataClasses.RelatedEnd.Add(IEntityWrapper wrappedEntity, Boolean applyConstraints)
w System.Data.Objects.DataClasses.EntityReference`1.set_ReferenceValue(IEntityWrapper value)
w System.Data.Objects.DataClasses.EntityReference.SetEntityKey(EntityKey value, Boolean forceFixup)
w System.Data.Objects.EntityEntry.FixupEntityReferenceToPrincipal(EntityReference relatedEnd, EntityKey foreignKey, Boolean setIsLoaded, Boolean replaceExistingRef)
w System.Data.Objects.EntityEntry.FixupReferencesByForeignKeys(Boolean replaceAddedRefs)
w System.Data.Objects.ObjectStateManager.FixupReferencesByForeignKeys(EntityEntry newEntry, Boolean replaceAddedRefs)
w System.Data.Objects.ObjectStateManager.AddEntry(IEntityWrapper wrappedObject, EntityKey passedKey, EntitySet entitySet, String argumentName, Boolean isAdded)
w System.Data.Common.Internal.Materialization.Shaper.HandleEntityAppendOnly[TEntity](Func`2 constructEntityDelegate, EntityKey entityKey, EntitySet entitySet)
w lambda_method(Closure , Shaper )
w System.Data.Common.Internal.Materialization.Coordinator`1.ReadNextElement(Shaper shaper)
w System.Data.Common.Internal.Materialization.Shaper`1.SimpleEnumerator.MoveNext()
w TCS.bos.Infrastructure.Data.MainModule.Repositories.EmployeeRepository.GetEmployeesEvacuationTimeSheet(Int64 dateHour)
w TCS.bos.Domain.MainModule.Employees.EmployeeTimeSheetService.GetEmployeesEvacuationTimeSheet(Int64 dateHour)
w TCS.plg.TimeSheets.ViewModels.TimeSheetsGridViewModel.GetAll2()
w TCS.plg.TimeSheets.ViewModels.TimeSheetsGridViewModel.<>c__DisplayClass4.<FilterCommand>b__2()
w TCS.Core.Caliburn.Invocation.BackgroundTask.<>c__DisplayClassd.<.ctor>b__4(Object s, DoWorkEventArgs e) w D:\VS2010\CaliburnMicro\caliburnmicro_a63379fba70a\TCS.2.3\TCS.Core\Caliburn\Invocation\BackgroundTask.cs:wiersz 41
w System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
w System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)
【问题讨论】：
-
在创建查询和枚举查询之间你会做什么？它是延迟的，因此在您尝试枚举之前，您之前所做的任何事情都不会发生。
-
你是对的，但这正是我使用的代码......
标签： entity-framework linq thread-safety linq-to-entities