Opening dbobjects inside a dbobjectcollection

[Anonymous]

Hello all,

I am just starting to learn VB.NET and I am trying to get the length of polyline segments.

I ask the user to select the polylines and I explode them using entity.explode. This function provides the exploded segments as a dbobjectcollection. Nevertheless, when I try to open the dbobjects inside the collection I get an "exception error".

This is my code, I am getting the error in the bold line:

Public Class ARCommands

    <CommandMethod("getlineslength")> _
    Public Sub getlineslength()
        Dim myDWG As Document = _
            Application.DocumentManager.MdiActiveDocument
        Dim myEd As Editor = myDWG.Editor
        Dim acTypValAr(0) As TypedValue
        acTypValAr.SetValue(New  _
                            TypedValue(DxfCode.Start, _
                                       "LWPOLYLINE"), 0)
        Dim acSelFtr As SelectionFilter = _
            New SelectionFilter(acTypValAr)
        Dim myPSR As PromptSelectionResult = _
            myEd.GetSelection(acSelFtr)

        Dim myobjects As DBObjectCollection = _
            New DBObjectCollection()

        If myPSR.Status = PromptStatus.OK Then
            Using myTrans As Transaction = _
                myDWG.Database.TransactionManager.StartTransaction()

                For Each so As SelectedObject In myPSR.Value
                    Dim myEnt As Entity = _
                        so.ObjectId.GetObject(OpenMode.ForRead)
                    myEnt.Explode(myobjects)
                Next

                For I As Integer = 1 To myobjects.Count - 1

                    Dim myobject As DBObject = _
                        myTrans.GetObject(myobjects.Item(I - 1). _
                                          ObjectId, OpenMode.ForRead)
                    Dim myline As Line = _
                        myTrans.GetObject(myobject.ObjectId, _
                                          OpenMode.ForRead)
                    MsgBox(myline.Length.ToString)
                Next
                myTrans.Commit()
            End Using
        End If
    End Sub
End Class

Thank you,

Daniel Archila

[norman.yuan · Accepted solution]

The entities in the DBObjectCollection, as the result of Entity.Explode(), are not database residing objects, thus you do not need to open it with Transaction for read/write. You just go ahead work with them, such as:

foreach (var ent in myCol)

{

   Line lin=ent as Line;

   if (lin!=null)

   {

      double l=lin.Length;

   }

}

Do not forget to dispose them if you are not intend to append them into databse.

[Anonymous]

I got it. Thank you very much Norman!