LINQ到實體，ToList（）從非UI線程

叫我用EF 4.0和它的作品真的很好，當異常，但問題發生時我打電話查詢：LINQ到實體，ToList（）從非UI線程

var query = from employee in employees from cr in employee.RcpCrossRegister select new { employee, cr } 然後當我打電話

var list = query.ToList()

我得到異常

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)

來源

2011-04-20 Robertok

你在創建查詢和枚舉它之間做了什麼？這是推遲的，所以你以前做的任何事情都不會發生，直到你試圖枚舉。 – 2011-04-20 08:28:50

你是對的，但這正是我使用的代碼... – Robertok 2011-04-20 08:34:17

Entity Framework不是線程安全的，只能在創建它的線程上使用ObjectContext。

來源

2011-04-20 08:29:24

...重要提示：此異常僅在從非UI線程調用時纔會發生......我懷疑「關係修復」使得一些工作收集和引起異常，但不知道如何解決它... ---------- 我沒有任何問題，當我從UI線程調用它，但我需要顯示進度欄在UI線程上...... – Robertok 2011-04-20 08:31:33

它可以在UI線程上工作，因爲你可能在UI線程上創建了ObjectContext ... – 2011-04-20 08:32:53

@Thomas Levesque：「不是線程安全的」不等於「只能在線程上使用創造它「。你能看到區別麼？ – 2011-04-20 08:59:51

LINQ到實體，ToList（）從非UI線程

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