Help with deleting multiple copies of blocks (not anon) with selection set

[cmccartney]

As part of a larger routine ive inserted multiple copies of four different blocks (all named, none anon), so now im trying to delete them all at once when im done with them. so i figured create a selection set, the erase. im i going about it all wrong? heres the code for the eraser so far:

Private Sub eraser()
        Dim doc As Document = Application.DocumentManager.MdiActiveDocument
        Dim db As Database = doc.Database
        Dim ed As Editor = doc.Editor
        Using tr As Transaction = db.TransactionManager.StartTransaction()
            Dim mytvs(3) As TypedValue
            mytvs(3) = New TypedValue(2, "Standard")
            mytvs(3) = New TypedValue(2, "Compact")
            mytvs(3) = New TypedValue(2, "Handicap")
            mytvs(3) = New TypedValue(2, "Van")
            Dim myfilter As New SelectionFilter(mytvs)
            Dim mypsr As PromptSelectionResult = ed.SelectAll(myfilter)
            If mypsr.Status = PromptStatus.OK Then
                Dim sset As SelectionSet = mypsr.Value
                Dim bt As BlockTable = tr.GetObject(db.BlockTableId, OpenMode.ForRead)
                Dim btr As BlockTableRecord = bt(sset.GetObjectIds.ToString).GetObject(OpenMode.ForRead)
                For Each obid As ObjectId In btr.GetBlockReferenceIds(True, True)
                    Dim ent As Entity = obid.GetObject(OpenMode.ForWrite)
                    ent.Erase()
                Next
            End If
            tr.Commit()
        End Using
    End Sub

i think the highlited portion is the problem.

[BlackBox]

Rather than attempting to create a selection set of the blocks added to the Database during your Transaction's Using statement (because you only need one Transaction), testing that the selection set is valid, iterating the selection set, and deleting each ObjectId... Perhaps it would be simpler to instead just store the Block's ObjectId to an IEnumerable, public static List<ObjectId>, or public static List<Entity> Property Object at the time the Block's are added to the Database, that can then be used to 'clean up' after the fact?

[BlackBox]

In the event the C# jargon doesn't make sense:

Pseudo-code (C#):

public static List<ObjectId> myBlocks { get; set; }

Pseudo-code (VB.NET, converted using developerFusion):

Public Shared Property myBlocks() As List(Of ObjectId)
    Get
        Return m_myBlocks
    End Get
    Set
        m_myBlocks = Value
    End Set
End Property
Private Shared m_myBlocks As List(Of ObjectId)

[_gile]

Hi,

I agree with RenderMan, the best way is to store the BlockReference ObjectIdS in a collection (ObjectIdCollection) when they're added to the Database. But there's no need to use a class property as the ObjectIdCollection won't be got from outside of the class, a private field would do the trick (and don't set the field static/Shared which means per session rather than per document).

If you want to keep on the SelectionSet route, change your selection filter building to :

            Dim mytvs(1) As TypedValue
            mytvs(0) = New TypedValue(0, "INSERT")
            mytvs(1) = New TypedValue(2, "Standard,Compact,Handicap,Van")
            Dim myfilter As New SelectionFilter(mytvs)

And don't use the BlockTableRecord.GetBlockReferenceIds() method, just iterate the Selection set :

                Dim sset As SelectionSet = mypsr.Value
                For Each obid As ObjectId In sset.GetObjectId()
                    Dim ent As Entity = obid.GetObject(OpenMode.ForWrite)
                    ent.Erase()
                Next

If you want to go on the BlockTableRecord.GetBlockReferenceIds() method, you do not need a selection set, iterate the BlockTable looking for BlockTableRecord which Name matches the ones you're looking for, the get the references ObjectId, open them and erase them.

[cmccartney]

I'm definetly open to not using a selection set. hrmm so your saying create an objectidcollection within my block insertion sub, then pass that collection to the eraser sub? Insertion and deletion are performed with seperate button click events if that matters.

[BlackBox]

But there's no need to use a class property as the ObjectIdCollection won't be got from outside of the class, a private field would do the trick (and don't set the field static/Shared which means per session rather than per document).

Perhaps my logic is flawed (I am still only learning)... How is using a non-static (per-Document) Field better, more efficient, etc. than using a single static List<ObjectId>, which in theory *should* invoke the Add() Method at the time the BlockReference is added to the Database, and invokes the Remove() Method when done (perhaps in a Finally block?)...???

I'm definetly open to not using a selection set. hrmm so your saying create an objectidcollection within my block insertion sub, then pass that collection to the eraser sub? Insertion and deletion are performed with seperate button click events if that matters.

So long as the ObjectId Collection remains in scope (which it *should*, if you're passing it as a parameter)... Yes, that is correct (AFAIK).

[_gile]

If your insertion sub and your eraser sub are within the same class (as they should), within this class you can define a private field in this class (out of any method). This field can be considered as global variable within the class and can be accessed by both subs.

Public Class Dialog

    Private blocks As ObjectIdCollection

    Private Sub btnInsert_Click(sender As Object, e As EventArgs) Handles btnInsert.Click
        ' ...
        Dim id As ObjectId = modelSpace.AppendEntity(blockRef)
        blocks.Add(id)
        ' ...
    End Sub

    Private Sub btnErase_Click(sender As Object, e As EventArgs) Handles btnErase.Click
        ' ...
        For Each id As ObjectId In blocks
            Dim br As BlockReference = id.GetObject(OpenMode.ForWrite)
            br.Erase()
        Next
        blocks.Clear()
        ' ...
    End Sub

    ' ...
End Class

[_gile]

Perhaps my logic is flawed (I am still only learning)... How is using a non-static (per-Document) Field better, more efficient, etc. than using a single static List<ObjectId>, which in theory *should* invoke the Add() Method at the time the BlockReference is added to the Database, and invokes the Remove() Method when done (perhaps in a Finally block?)...???

I'll try to explain my point.
Firstly, I think it's not necessary to define a property as long as the data won't be used from outside of the class. A class field is sufficient. This field may be any type which suits the purpose: a List<ObjectId> (List(Of ObjectId) in VB) or an ObjectIdCollection.
Secondly I think it is not a good practice to use the static (Shared in VB) modifier when there's no need too (whatever the modifier applies to: field or property). Mostly, in this case where dealing with ObjectId which are document resident.

Try this little snippet, in a drawing run TEST1 and TEST2, in the same session, if you open a new drawing and run TEST2 (whatever you've run TEST1 or not in this session) an exception will occur.

using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Runtime;

namespace StaticFieldTest
{
    public class Commands
    {
        private static ObjectIdCollection staticIds = new ObjectIdCollection();

        [CommandMethod("Test1")]
        public void Test1()
        {
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            PromptEntityResult per = ed.GetEntity("\nSelect an entity: ");
            if (per.Status == PromptStatus.OK)
                staticIds.Add(per.ObjectId);
        }

        [CommandMethod("Test2")]
        public void Test2()
        {
            Database db = HostApplicationServices.WorkingDatabase;
            if (staticIds == null)
                Application.ShowAlertDialog("Null");
            else
                foreach (ObjectId id in staticIds)
                using (Entity ent = (Entity)id.Open(OpenMode.ForWrite))
                {
                    ent.Highlight();
                }
        }
    }
}

[BlackBox]

I'll try to explain my point.

Thanks for clarifying, Gile... Great job (as always).

[cmccartney]

Hrmm i think i missing something, i was unable to get this to work using either way. although i am thinking selection set my be the way to go afterall as i want to be able to delete these blocks even if they were already in teh drawing at the start of teh acad session (if i started placing, but then interrupted and had to come back later). so heres the insertion code as it stood before i attempted your suggestions. thoughts? and thanks again for the help, i am definetly learning things from this

Imports System
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
Imports Autodesk.AutoCAD.EditorInput

Public Class StallCounterInterface
    Private Sub StallCounterInterface_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Counter()
    End Sub
    Public Sub blocktest(ByVal BlockName As String)
        Dim doc As Document = Application.DocumentManager.MdiActiveDocument
        Dim db As Database = doc.Database
        Dim ed As Editor = doc.Editor
        'test if block exists
        Using tr As Transaction = db.TransactionManager.StartTransaction()
            Dim bt As BlockTable = tr.GetObject(db.BlockTableId, OpenMode.ForRead)
            'insert source file if block not found
            If Not bt.Has(BlockName) Then
                Dim origin As New Point3d(0, 0, 0)
                Dim filename As String = "C:\mkacadd_Hybrid\Civil3D\CAD data\Support\Blocks\StallCount.dwg"
                ed.WriteMessage(vbLf & BlockName & " block does not exist, now inserting source file!")
                Using dbdwg As New Database(False, True)
                    dbdwg.ReadDwgFile(filename, IO.FileShare.Read, True, "")
                    Dim blkid As ObjectId
                    blkid = db.Insert(filename, dbdwg, True)
                    Dim obr As New BlockReference(origin, blkid)
                    Dim obtr As BlockTableRecord = tr.GetObject(bt(BlockTableRecord.ModelSpace), OpenMode.ForWrite)
                    obtr.AppendEntity(obr)
                    tr.AddNewlyCreatedDBObject(obr, True)
                    'erases source file
                    obr.Erase(True)
                    tr.Commit()
                End Using
            End If
        End Using
        'initiate loop for cotninous block placement unitl user cancels
        Dim LoopControl As Boolean = True
        Do While LoopControl
            doc.LockDocument()
            Me.Hide()
            Using tr As Transaction = db.TransactionManager.StartTransaction()
                Dim bt As BlockTable = tr.GetObject(db.BlockTableId, OpenMode.ForRead)
                Dim id As ObjectId = bt(BlockName)
                ' Get insertion point
                Dim ppo As New PromptPointOptions(vbLf & "Specify insertion point, press [ESC] to return:")
                Dim ppr As PromptPointResult = ed.GetPoint(ppo)
                ' Exit if the user presses ESC or cancels the command
                If ppr.Status = PromptStatus.Cancel Then Exit Do
                If ppr.Status = PromptStatus.OK Then
                    Dim pts As Point3d = ppr.Value
                    Dim ptstr As New Point2d(ppr.Value.X, ppr.Value.Y)
                    Dim ppor As New PromptPointOptions(vbLf & "Specify Rotation point:")
                    'rubber band to show rotation
                    ppor.UseBasePoint = True
                    ppor.BasePoint = pts
                    Dim pprr As PromptPointResult = ed.GetPoint(ppor)
                    Dim ptend As New Point2d(pprr.Value.X, pprr.Value.Y)
                    ' Create a block reference
                    Dim br As New BlockReference(pts, id)
                    ' Get Model space
                    Dim btr As BlockTableRecord = tr.GetObject(bt(BlockTableRecord.ModelSpace), OpenMode.ForWrite)
                    ' Add the block reference to Model space
                    btr.AppendEntity(br)
                    tr.AddNewlyCreatedDBObject(br, True)
                    'Rotate block based on insertion and rotation points
                    Dim curucsmat As Matrix3d = ed.CurrentUserCoordinateSystem
                    Dim curUCS As CoordinateSystem3d = curucsmat.CoordinateSystem3d
                    Dim ang = ptstr.GetVectorTo(ptend).Angle.ToString()
                    Dim rot = Math.Truncate(ang * 10000) / 10000
                    br.TransformBy(Matrix3d.Rotation(rot, curUCS.Zaxis, New Point3d(ppr.Value.X, ppr.Value.Y, 0)))
                    tr.Commit()
                End If
            End Using
        Loop
        Counter()
        Me.Show()
    End Sub
    Private Sub Counter()
        Dim doc As Document = Application.DocumentManager.MdiActiveDocument
        Dim ed As Editor = doc.Editor
        Dim numS As Integer = 0
        Dim numC As Integer = 0
        Dim numH As Integer = 0
        Dim numV As Integer = 0
        Dim numT As Integer = 0
        Using tr As Transaction = doc.TransactionManager.StartTransaction()
            Dim mytvs(0) As TypedValue
            mytvs(0) = New TypedValue(0, "Insert")
            Dim myfilter As New SelectionFilter(mytvs)
            Dim mypsr As PromptSelectionResult = ed.SelectAll(myfilter)
            If mypsr.Status = PromptStatus.OK Then
                Dim sset As SelectionSet = mypsr.Value
                For Each id As ObjectId In mypsr.Value.GetObjectIds
                    Dim br As BlockReference = id.GetObject(OpenMode.ForRead)
                    Select Case br.Name
                        Case "Standard"
                            numS = numS + 1
                        Case "Compact"
                            numC = numC + 1
                        Case "Handicap"
                            numH = numH + 1
                        Case "Van"
                            numV = numV + 1
                        Case Else
                    End Select
                    numT = numS + numC + numH + numV
                Next
            End If
            tr.Commit()
        End Using
        StdCnt.Text = numS
        ComCnt.Text = numC
        HanCnt.Text = numH
        VanCnt.Text = numV
        TtlCnt.Text = numT
    End Sub
    Private Sub eraser()
       
    End Sub

    Private Sub StdBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles StdBtn.Click
        Dim BlockName As String = "Standard"
        blocktest(BlockName)
    End Sub

    Private Sub CompBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CompBtn.Click
        Dim BlockName As String = "Compact"
        blocktest(BlockName)
    End Sub

    Private Sub VanBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles VanBtn.Click
        Dim BlockName As String = "Van"
        blocktest(BlockName)
    End Sub

    Private Sub HandBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles HandBtn.Click
        Dim BlockName As String = "Handicap"
        blocktest(BlockName)
    End Sub

    Private Sub ExitBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExitBtn.Click
        Me.Close()
        'set current layer to layer before app was run.
        Application.SetSystemVariable("clayer", Laycurrent.laycur)
    End Sub

    Private Sub Erasebtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Erasebtn.Click
        eraser()
    End Sub
End Class