c# - ObservableCollection Refresh is not working, when dynamic allocated -

public observablecollection<model.childcommand> childcommands { get; private set; } 

childcommands bound datagrid.

both segments show me items in datagrid.

but in segment 1 datagrid items doesn't refresh automatically when collection changes. segment two, refresh works.

segment 1:

var childs = child in m_context.childcommand.local                          select child;   this.childcommands = new observablecollection<model.childcommand>(childs); 

segment 2:

this.childcommands = m_context.childcommand.local; 

how automatic refresh using segment one?

the reason segment 1 not updating automatically end binding different observablecollection instance.

when m_context.childcommand.local changes, segment 2 datagrid gets notified because bound observable collection instance. segment 1 datagrid bound different observable collection instance (that create when new observablecollection(childs).

if want both of them bound m_context.childcommand.local observable collection should implement such instead of creating different observable collection instance segment 1.