There is a group structure, A group has B .......

node struct is
{A -> B -> C -> D}
first delete C , then delete B and add E after D. Next delete D and add F after E. Finally delete E

At this moment, Null Reference Exception happen!!!
I dont understand why error will occur, plz help!!

Box de = userChart.Selection.Boxes[0];
Group parent = box.MasterGroup;
Group sub = box.SubordinateGroup;
Box main = ((Box)parent.MainObject);
Group master = userChart.FindGroup(main.Tag);
for(int i = 0; i < sub.AttachedObjects.Count; i++)
{
     Box b = (Box)sub.AttachedObjects[i];   
     master.AttachedObjects.Add(b);
     master.AttachToCorner(b,0);
     Arrow link = userChart.CreateArrow(main, b);
}
userChart.DeleteObject(de);
rearrange(); <----- Refresh treelayout

Thx All

Thanks for your fast reply!!!
But also not work
at last Node E does not contain any Master Group
(origial design is A will contain E, then i could delete E too, but i want to delete E, Null Reference in the MasterGroup and its MainOject)
Help!!!! Stoyo
THX

Hi,

It seems the "Group master" variable did not point correctly to the parent group. This code seems to work better:

if(userChart.Selection.Boxes.Count > 0)
{
  Box de = userChart.Selection.Boxes[0];
  Group parent = de.MasterGroup;
  Group sub = de.SubordinateGroup;
  Box main = ((Box)parent.MainObject);

  for(int k = 0; k < sub.AttachedObjects.Count; k++)
  {
    Box b = (Box)sub.AttachedObjects[k];
    b.AttachTo(main, AttachToNode.TopLeft);
    Arrow link = userChart.CreateArrow(main, b);
  }
  userChart.DeleteObject(de);
  rearrange();
}
 

Stoyan