AutoCAD .NET Problems

[Anonymous]

I keep running into a lot of wierd issues while programing against AutoCAD. Here's the latest one.

The code just checks to see if a layer exists and if not, creates it. This code creates an error in AutoCAD. I get a message box that says 'Error Handler re-entered'. Which crashes AutoCAD. I do have time to pause the debugger and it happens inside the End Using statement, wich I will assume the crash is happening during the call to the transactions .Dispose() method.

            Using tr As Transaction = dwg.TransactionManager.StartTransaction

                Dim lt As LayerTable = CType(tr.GetObject(dwg.LayerTableId, OpenMode.ForRead), LayerTable)

                If lt.Has(Name) Then
                    Return
                Else
                    Dim ly As New LayerTableRecord
                    ly.Name = Name
                    lt.UpgradeOpen()
                    lt.Add(ly)
                    tr.AddNewlyCreatedDBObject(ly, True)
                End If

                tr.Commit()
            End Using

However, the following code works without error:

            Using tr As Transaction = dwg.TransactionManager.StartTransaction

                Dim lt As LayerTable = CType(tr.GetObject(dwg.LayerTableId, OpenMode.ForRead), LayerTable)

                If Not lt.Has(Name) Then
                    Dim ly As New LayerTableRecord
                    ly.Name = Name
                    lt.UpgradeOpen()
                    lt.Add(ly)
                    tr.AddNewlyCreatedDBObject(ly, True)
                End If

                tr.Commit()
            End Using

The only difference being, in the first example if the name already exists, the transaction is not committed (although it shouldn't matter because nothing was changed) if the name exists, so it has to rollback when it's disposed.

I feel like this is an AutoCAD side bug. Does anyone else have any experience with such error?

And before you ask, yes, all my non-database resident object are disposed of properly. And no, I'm not accessing objects outside the transaction they were created/opened in.

[arcticad]

Your code works fine here.

Make sure you are locking the current the drawing.

    Sub CreateLayer(ByVal name As String)
        Dim DWG As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Using lock As DocumentLock = Application.DocumentManager.MdiActiveDocument.LockDocument
            Using tr As Transaction = DWG.TransactionManager.StartTransaction
                Dim lt As LayerTable = CType(tr.GetObject(DWG.Database.LayerTableId, OpenMode.ForRead), LayerTable)

                If lt.Has(name) Then
                    Return
                Else
                    Dim ly As New LayerTableRecord
                    ly.Name = name
                    lt.UpgradeOpen()
                    lt.Add(ly)
                    tr.AddNewlyCreatedDBObject(ly, True)
                End If

                tr.Commit()
            End Using
        End Using

    End Sub

[Irvin]

Hello there,

I think he is checking if the layer in an eventhandler. If so that's the reason he gets this error.

Furter information would be nice.

Kind regards,

irvin

[Anonymous]

It was being called from an ObjectErased handler, which was called during an undo operation. Basically my code is a product configurator, the action is they deleted the production, then hit undo, so (although this is strange to me) the ObjectErased event is called with the DBObjects IsUndoing property set to true, so I have to rebuild the product.

So your saying I can create and commit a transaction in an event handler, but rolling it back would crash AutoCAD?

[Irvin · Accepted solution]

No transaction in Eventhandlers is what Autodesk prefers.

What you could do is use the CommandEnded event.

This is triggerd after the command is finished.

Kind regards,

Irvin

[Anonymous]

Ok I'll give that a try if I run into more trouble.