Exchange Web 服务：为什么 ItemId 不恒定？ [继续]

Question

正如其他人之前讨论过这个问题（例如，Exchange web services: why is ItemId not constant?），我想谈谈解决方案，我已经按照人们的建议将 Guid 标记为扩展属性，对我来说，这个解决方案有点像很好（虽然我不知道如何使它与事件一起工作）但只要应用程序正常工作，一旦应用程序重新启动，项目的扩展属性就会消失，所以我现在的问题是“如何在 EWS 项目上标记扩展属性并使其始终存在？” 这是更新日历项目（约会）的代码

public void SetGuidForAppointement(Appointment appointment)
{         
appointment.SetExtendedProperty((ExtendedPropertyDefinition)_appointementIdPropertyDefinition, Guid.NewGuid().ToString());
appointment.Update(ConflictResolutionMode.AlwaysOverwrite, SendInvitationsOrCancellationsMode.SendToNone);
}

这些是上面需要的属性定义。

_appointementIdPropertyDefinition = new ExtendedPropertyDefinition(DefaultExtendedPropertySet.Appointment, "AppointmentID", MapiPropertyType.String);
            _propertyDefinitionBases = new PropertyDefinitionBase[] { _appointementIdPropertyDefinition, ItemSchema.ParentFolderId, AppointmentSchema.Start, AppointmentSchema.End, 
AppointmentSchema.LegacyFreeBusyStatus, AppointmentSchema.Organizer };
            PropertySet = new PropertySet(BasePropertySet.FirstClassProperties, _propertyDefinitionBases);

因此，如果之前有人这样做过，他/她是否可以向我提供一个示例，即使应用程序退出，也可以将扩展属性标记在项目上。 谢谢

Answer 1

经过一段时间的尝试和搜索，我找到了解决问题的方法。

private static readonly PropertyDefinitionBase AppointementIdPropertyDefinition = new ExtendedPropertyDefinition(DefaultExtendedPropertySet.PublicStrings, "AppointmentID", MapiPropertyType.String);
public static PropertySet PropertySet = new PropertySet(BasePropertySet.FirstClassProperties, AppointementIdPropertyDefinition);


//Setting the property for the appointment 
 public static void SetGuidForAppointement(Appointment appointment)
{
    try
    {
        appointment.SetExtendedProperty((ExtendedPropertyDefinition)AppointementIdPropertyDefinition, Guid.NewGuid().ToString());
        appointment.Update(ConflictResolutionMode.AlwaysOverwrite, SendInvitationsOrCancellationsMode.SendToNone);
    }
    catch (Exception ex)
    {
        // logging the exception
    }
}

//Getting the property for the appointment
 public static string GetGuidForAppointement(Appointment appointment)
{
    var result = "";
    try
    {
        appointment.Load(PropertySet);
        foreach (var extendedProperty in appointment.ExtendedProperties)
        {
            if (extendedProperty.PropertyDefinition.Name == "AppointmentID")
            {
                result = extendedProperty.Value.ToString();
            }
        }
    }
    catch (Exception ex)
    {
     // logging the exception
    }
    return result;
}