Unload Xref in .NET

[Anonymous]

In searching some other threads, I see this was discussed, but I can't find any reference to a solution in VB.

I was attempting to change the .IsUnloaded boolean flag on a Block Table Record (as the Developer Help does show this as read/write), but I see that as it changes the flag, even a .Commit won't actually unload the Xref. 

Does anyone have some VB code as an example of how to unload an Xref programmatically? Or do I have to resort to feeding the command line some strings? 

Thanks in advance,
Drew

[Anonymous]

With a little more digging into some reference material; perhaps I should be asking whether anyone has an example of how they use XrefReloadOperation?

[absStructural · Accepted solution]

Have you had a look at Database.UnloadXrefs?

[Anonymous]

I have now!! Thanks for the help as I didn't know this method existed. 

A basic example of how I got it to work:

Public Sub unloadBaseXref(ByVal strName As String)

'get the active document, editor and database
Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
Dim acDocEd As Editor = acDoc.Editor
Dim acCurDb As Database = acDoc.Database

'start a transaction
Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction

'create a collection to house the xref object id
Dim colObjId As ObjectIdCollection = New ObjectIdCollection

'open the block table for read
Dim acBlkTbl As BlockTable = acTrans.GetObject(acCurDb.BlockTableId, OpenMode.ForRead)

'step through each record in the table
For Each acObjId As ObjectId In acBlkTbl

'open the block table record for read
Dim acBlkTblRec As BlockTableRecord = acTrans.GetObject(acObjId, OpenMode.ForRead)

'if the current block matches the supplied string
If acBlkTblRec.Name Like strName Then

'and if the current block is loaded
If acBlkTblRec.IsUnloaded = False Then

'add the object id to the collection
colObjId.Add(acBlkTblRec.ObjectId)

'unload the xref in the collection
acCurDb.UnloadXrefs(colObjId)

'document the change
acDocEd.WriteMessage(vbLf & strName & " unloaded")

End If

End If

Next

'commit the changes and dispose of the transaction
acTrans.Commit()

End Using

End Sub