applying plot styles to layers

[EvolveTraining]

I am truely stuck, someone help me please.

As the subject states, I am trying to apply a plotstyle to a layer. I can create the layer and apply a plot style but as soon as I create another layer with a different plotstyle, the layers I previously created lose their plot style (it appears to be removed from the drawing) 

I have tried workarounds such as placing an object and applying a plotstyle then deleting that plot style and that still doesnt seem to append it to the drawing.

this is my code so far:

    Public Sub addPltStToLayer(ByVal id As ObjectId, ByVal pltsty As String)
        Dim thisDrawing As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim thisDB As Database = thisDrawing.Database
        Dim trans As Transaction = thisDB.TransactionManager.StartTransaction
        Using locker As DocumentLock = thisDrawing.LockDocument

            Dim dict As DictionaryWithDefaultDictionary = trans.GetObject(thisDB.PlotStyleNameDictionaryId, DatabaseServices.OpenMode.ForRead)
            Dim ltr As LayerTableRecord = trans.GetObject(id, DatabaseServices.OpenMode.ForWrite)
            ltr.PlotStyleNameId = dict.GetAt(pltsty)

        End Using
        trans.Commit()
        trans.Dispose()

    End Sub

    Public Sub addPstyle()

        Dim thisDrawing As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim thisDB As Database = thisDrawing.Database
        Using trans As Transaction = thisDB.TransactionManager.StartTransaction

            Using placeHold As PlaceHolder = New PlaceHolder
                Dim dict As DictionaryWithDefaultDictionary = trans.GetObject(thisDB.PlotStyleNameDictionaryId, DatabaseServices.OpenMode.ForWrite)

                If dict.Contains(PltStBut.Text) Then
                    'do nothing, its already here
                Else
                    dict.SetAt(PltStBut.Text, thisDB.AcadDatabase)
                End If
                trans.Commit()
            End Using
        End Using

    End Sub

[EvolveTraining]

It appears nobody actually knows how to apply a plot style to a layer properly - there must be someone out there who has the infinite wisdom to be able to answer this - please!

[EvolveTraining · Accepted solution]

After well over 7 hours of coding a bazillion different methods of trying to get this working, I got it!!!!

If and when I get a chance to tidy the code, I will do but this is rough and ready for anyone else stuck

The final code (There is, of course, a dialog behind the code which gives the layer properties):

Private Sub AddLayer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

'1. append plot style to drawing
addPlotStyle()
'2. add layer
Dim layID As ObjectId = addLayerToDWG()
'2. AddPlotStyleTo Layer
appendPStyle(layID)
End Sub

Public Sub appendPStyle(ByVal layID As ObjectId)

        Dim thisDrawing As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim thisDB As Database = thisDrawing.Database
        If thisDB.PlotStyleMode = False Then
            Using locker As DocumentLock = thisDrawing.LockDocument
                Using trans As Transaction = thisDB.TransactionManager.StartTransaction
                    Dim dict As DictionaryWithDefaultDictionary = trans.GetObject(thisDB.PlotStyleNameDictionaryId, DatabaseServices.OpenMode.ForRead)
                    Dim ltr As LayerTableRecord = trans.GetObject(layID, DatabaseServices.OpenMode.ForWrite)
                    If dict.Contains(PltStBut.Text) = True Then
                        ltr.PlotStyleNameId = dict.GetAt(PltStBut.Text)
                    End If
                    trans.Commit()

                End Using
            End Using

        End If

    End Sub


    Public Sub addPlotStyle()

        Dim thisDrawing As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim thisDB As Database = thisDrawing.Database
        Using locker As DocumentLock = thisDrawing.LockDocument
            Using trans As Transaction = thisDB.TransactionManager.StartTransaction
                Using plHldr As PlaceHolder = New PlaceHolder
                    Dim dict As DictionaryWithDefaultDictionary = trans.GetObject(thisDB.PlotStyleNameDictionaryId, DatabaseServices.OpenMode.ForWrite)
                    If dict.Contains(PltStBut.Text) = True Then

                        dict.SetAt(PltStBut.Text, plHldr)
                        trans.Commit()
                    End If
                End Using
            End Using
        End Using


    End Sub

    Public Function addLayerToDWG()
        'create layer here
        Dim thisDrawing As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim thisDB As Database = thisDrawing.Database
        Dim trans As Transaction = thisDB.TransactionManager.StartTransaction
        Dim ed As Editor = thisDrawing.Editor
        Dim lt As LayerTable = trans.GetObject(thisDB.LayerTableId, DatabaseServices.OpenMode.ForRead)

        'else continue and create layer
        Dim lockMeUp As DocumentLock = thisDrawing.LockDocument
        Dim newLay As New LayerTableRecord
        newLay.Name = LaNmVal.Text

        newLay.Color = Autodesk.AutoCAD.Colors.Color.FromColorIndex(Colors.ColorMethod.ByAci, CType(Strings.Right(ColPickBut.Text, Len(ColPickBut.Text) - 7), Short))
        If lWeightBut.Text = "Default" Then
            newLay.LineWeight = -3
        Else
            newLay.LineWeight = Replace(lWeightBut.Text, ".", "")
        End If

        'add the linetype
        Dim acLinTbl As LinetypeTable
        acLinTbl = trans.GetObject(thisDB.LinetypeTableId, DatabaseServices.OpenMode.ForRead)
        If acLinTbl.Has(LStyleList.SelectedItem) = True Then
            'Set the linetype for the layer
            newLay.LinetypeObjectId = acLinTbl(LStyleList.SelectedItem)
        End If

        lt.UpgradeOpen()
        lt.Add(newLay)
        trans.AddNewlyCreatedDBObject(newLay, True)
        'add layer description
        newLay.Description = DescVal.Text

        trans.Commit()
        lockMeUp.Dispose()
        trans.Dispose()

        Return newLay.Id

    End Function