Solved: Read field in AUTOCAD block attribute

[fixo]

Hi ALe, I posted solution on swamp as well
Here is a quick and dirty code
[Code]
<CommandMethod("foo")>

Public Sub 
GetFieldFromAttribute()
Dim doc As Document = 
Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
Dim db As Database = 
doc.Database
Dim ed As Editor = doc.Editor

Try

Dim tab As String = Autodesk.AutoCAD.ApplicationServices.Application.GetSystemVariable("ctab").ToString
Dim blockname As String = ed.GetString(vbLf & "Enter blockname:").StringResult
Dim opts As PromptSelectionOptions = New 
PromptSelectionOptions
opts.SingleOnly =True
opts.MessageForRemoval = vbLf & "Select block only"
opts.MessageForAdding = vbLf & "Select single block"
Dim filt As SelectionFilter = New SelectionFilter({New TypedValue(0, "insert"), 
New TypedValue(2, blockname), New TypedValue(410, tab)})
Dim psr As PromptSelectionResult = ed.GetSelection(opts, filt)
If psr.Status <> PromptStatus.OK Then Exit
    Sub
    If psr.Value.Count <> 1 Then Exit 
    Sub
    Dim id As ObjectId = psr.Value.GetObjectIds(0)
    If id.IsNull Then Exit 
        Sub
        Using tr As Transaction = db.TransactionManager.StartTransaction()
        Dim obj As DBObject = tr.GetObject(psr.Value.GetObjectIds(0), OpenMode.ForRead)
        If TypeOf obj Is BlockReference Then
            Dim bref As BlockReference = CType(tr.GetObject(id, OpenMode.ForRead), BlockReference)
            Dim attcoll As AttributeCollection = bref.AttributeCollection
            Dim att As AttributeReference
            For Each aid As ObjectId In attcoll
                Dim aobj As DBObject = tr.GetObject(aid, OpenMode.ForRead)
                att = TryCast(DirectCast(aobj, AttributeReference), AttributeReference)
                If att Is Nothing Then Exit 
                Sub
                If att.Tag.Equals("LENGTH", StringComparison.CurrentCultureIgnoreCase) Then
                   If att.HasFields Then
                        Dim fld As Field = tr.GetObject(att.GetField(), OpenMode.ForRead)
                        Dim code As String = fld.GetFieldCode
                        Dim pos1 As Int32 = code.IndexOf("_ObjId")
                        Dim pos2 As Integer = code.IndexOf(">%")
                        Dim leng1 As Integer = "_ObjId".Length
                        Dim leng2 As Integer = ">%".Length
                        Dim idstr As String = code.Substring(pos1 + leng1 + 1, pos2 - (pos1 + leng1) - 1)
                        MsgBox("ID from field code: " & idstr)
                        Dim objId As ObjectId = New ObjectId(New IntPtr(Convert.ToInt32(idstr)))
                        Dim fieldchild As DBObject = tr.GetObject(objId, OpenMode.ForRead)
                        If TypeOf fieldchild Is Polyline Then
                            Dim poly As Polyline = DirectCast(fieldchild, Polyline)
                            MsgBox("Compare:" & vbLf & "Return from attribute: " & 
                            att.TextString & vbLf & "Return from Polyline: " & 
                            poly.Area.ToString)
                        End If
                        Exit For
                    End If
                End If
            Next
        End If
        End Using
        Catch ex As 
        Autodesk.AutoCAD.Runtime.Exception
        ed.WriteMessage(ex.Message + vbLf + ex.StackTrace)
     End Try
End Sub