The property 'RowId' is part of the object's key information and cannot be modified.

2016-10-20 10:19:46,667 [12] ERROR ClientApp.FormDownload - Error
System.InvalidOperationException: The property 'RowId' is part of the object's key information and cannot be modified.
在 System.Data.Entity.Core.Objects.EntityEntry.VerifyEntityValueIsEditable(StateManagerTypeMetadata typeMetadata, Int32 ordinal, String memberName)
在 System.Data.Entity.Core.Objects.EntityEntry.GetAndValidateChangeMemberInfo(String entityMemberName, Object complexObject, String complexObjectMemberName, StateManagerTypeMetadata& typeMetadata, String& changingMemberName, Object& changingObject)
在 System.Data.Entity.Core.Objects.EntityEntry.EntityMemberChanging(String entityMemberName, Object complexObject, String complexObjectMemberName)
在 System.Data.Entity.Core.Objects.EntityEntry.EntityMemberChanging(String entityMemberName)
在 System.Data.Entity.Core.Objects.ObjectStateEntry.System.Data.Entity.Core.Objects.DataClasses.IEntityChangeTracker.EntityMemberChanging(String entityMemberName)
在 System.Data.Entity.Core.Objects.Internal.SnapshotChangeTrackingStrategy.SetCurrentValue(EntityEntry entry, StateManagerMemberMetadata member, Int32 ordinal, Object target, Object value)
在 System.Data.Entity.Core.Objects.Internal.EntityWrapper`1.SetCurrentValue(EntityEntry entry, StateManagerMemberMetadata member, Int32 ordinal, Object target, Object value)
在 System.Data.Entity.Core.Objects.EntityEntry.SetCurrentEntityValue(StateManagerTypeMetadata metadata, Int32 ordinal, Object userObject, Object newValue)
在 System.Data.Entity.Core.Objects.ObjectStateEntryDbUpdatableDataRecord.SetRecordValue(Int32 ordinal, Object value)
在 System.Data.Entity.Core.Mapping.Update.Internal.PropagatorResult.SetServerGenValue(Object value)
在 System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.BackPropagateServerGen(List`1 generatedValues)
在 System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
在 System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.<Update>b__2(UpdateTranslator ut)
在 System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update[T](T noChangesResult, Func`2 updateFunction)
在 System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update()
在 System.Data.Entity.Core.Objects.ObjectContext.<SaveChangesToStore>b__35()
在 System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
在 System.Data.Entity.Core.Objects.ObjectContext.SaveChangesToStore(SaveOptions options, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction)
在 System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClass2a.<SaveChangesInternal>b__27()
在 System.Data.Entity.Infrastructure.DefaultExecutionStrategy.Execute[TResult](Func`1 operation)
在 System.Data.Entity.Core.Objects.ObjectContext.SaveChangesInternal(SaveOptions options, Boolean executeInExistingTransaction)
在 System.Data.Entity.Core.Objects.ObjectContext.SaveChanges(SaveOptions options)
在 System.Data.Entity.Internal.InternalContext.SaveChanges()
在 System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
在 System.Data.Entity.DbContext.SaveChanges()
在 ClientApp.FormDownload.<>c__DisplayClass9_0.<SensorSelected>b__0() 位置 F:CodeForGitBlitYunClientClientAppFormDownload.cs:行号 207