如何更有效地更新此可观察的集合？

Question

I am trying to update an object that contains an observable collection that contains another observable collection. The following code works, but it is ugly. How can I improve this?

ProfileBO contains the Observable Collection ZoneBOList. ZoneBOList contains the Observable Collection ZoneMonitorBOList. ZoneMonitorBOList IS the object collection for the object I am trying to add.

while (reader.Read())
{
   ZoneMonitorBO zoneMonitorBO = new ZoneMonitorBO();
   zoneMonitorBO.ZoneId = (int)reader["zone_id"];
   zoneMonitorBO.MonitorId = (int)reader["monitor_id"];

   ZoneBO zoneBO = new ZoneBO();
   //Pluck off the object from the observable collection that we need to update
   zoneBO = profileBO.ZoneBOList.FirstOrDefault(i => i.ZoneID == zoneMonitorBO.ZoneId);
   //Add the business object to the observable collection of the observable collection 
   zoneBO.ZoneMonitorBOList.Add(zoneMonitorBO);
   //remove the old object                        
   profileBO.ZoneBOList.Remove(profileBO.ZoneBOList.Where(c => c.ZoneID == zoneMonitorBO.ZoneId).Single());
   //add the updated object to the 'parent' observable collection
   profileBO.ZoneBOList.Add(zoneBO);
}

Answer 1

To me your entire code looks inconsistent:

• Why you creating and reassign ZoneBO?
• Why you looking for it second time? You do understand that you add the same object you modified then deleted by reference?
• Why you need to remove it and add again into collection?
• What if FirstOrDefault returns null and you get an exception?

Until you answer for this questions, all this can be simplified to just this:

while (reader.Read())
{
   var zoneMonitorBO = new ZoneMonitorBO();
   zoneMonitorBO.ZoneId = (int)reader["zone_id"];
   zoneMonitorBO.MonitorId = (int)reader["monitor_id"];

   var zoneBO = profileBO.ZoneBOList.FirstOrDefault(i => i.ZoneId == zoneMonitorBO.ZoneId);
   if(zoneBO != null)
   {
       zoneBO.ZoneMonitorBOList.Add(zoneMonitorBO);
   }
}