Find a block by name (.NET)

[ym.56789]

Hi, I am trying to create a function that will send a specific block to the bottom of the draworder. It should be simple, but I can't work it out.

The code should loop through all blocks in paperspace, and if their name contains "keymap" send them to the back. For some reason the only block refrence the code finds is the paperspace block reference itself. (When I step through I see that only one block reference name is checked = "*paper_space", the other block references don't seem to exist.

Here's the code:

    <Autodesk.AutoCAD.Runtime.CommandMethod("TEST_1")>
    Public Sub TEST_1()
        Dim doc As Document = DocumentManager.CurrentDocument
        Dim db As Database = doc.Database
        Dim ed As Editor = doc.Editor

        Try
            Using trans As Transaction = db.TransactionManager.StartTransaction()
                Dim bt As BlockTable = trans.GetObject(db.BlockTableId, OpenMode.ForRead)
                For Each r As ObjectId In bt
                    Dim btr As BlockTableRecord = trans.GetObject(r, OpenMode.ForRead)
                    If btr.IsLayout And btr.Name.ToLower.Contains("paper") Then
                        For Each entID In btr
                            Dim ent = TryCast(trans.GetObject(entID, OpenMode.ForRead), BlockReference)
                            If Not ent = Nothing Then
                                If ent.BlockName.ToLower.Contains("keymap") Then
                                    Dim OBJid As New ObjectIdCollection()
                                    OBJid.Add(entID)
                                    Dim dot As DrawOrderTable = trans.GetObject(btr.DrawOrderTableId, OpenMode.ForWrite)
                                    dot.MoveToBottom(OBJid)
                                End If
                            End If
                        Next

                    End If
                Next
            End Using
        Catch ex As Exception
            Throw ex
        End Try
    End Sub

(attached is the drawing I tested the code on - It contains the block in Layout1)

Any help would be appreciated.

[ed57gmc]

Do you understand how blocks work? You are searching for block definitions, not a BlockReference, which is what the INSERT command places.

[ym.56789]

I'm sorry - I probably don't understand blocks properly.

I thought that each block is stored as a record in the BlockTable, and when that block is inserted - for example, into model-space - a block reference is added to the model-space block table record. (I had also, assumed that a block reference was a type that inherited the Entity class)

I would be very appreciative if you could explain to me where I went wrong. I am trying to learn the .Net api (coming from a more programming background) and have found numerous examples online, but am still having trouble understanding some fundamentals.

(I did see that I can search for blocks by as following: EntID.ObjectClass.DxfName="INSERT", but from what I read this is not the recommended method, because it exposes the COM object as opposed to using the api methods.)

Thanks

[norman.yuan · Accepted solution]

the error lies in this line of code:

If ent.BlockName.ToLower.Contains("keymap") Then

BlockName property refers to the entity's owner block's name (e.g. PaperSpace block name). it should be:

If ent.Name.ToLower.Contains("...") Then

ASSUMING the block IS NOT A DYANMIC block.

Also, in case the layout have multiple block references you want to set DrawOrder, you should collect all possible ObjectIds in the For Each loop and set the DrawOrder after the loop, if the ObjectIdCollection.Count > 0:

If btr.IsLayout And btr.Name.ToLower.Contains("paper") Then
   Dim OBJid As New ObjectIdCollection()
   For Each entID In btr
       Dim ent = TryCast(trans.GetObject(entID, OpenMode.ForRead), BlockReference)
       If ent = Nothing Then Continue
       If ent.Name.ToLower.Contains("keymap") Then
            OBJid.Add(entID)
       End If
    Next
    If OBJid.Count > 0 Then
       Dim dot As DrawOrderTable = trans.GetObject(btr.DrawOrderTableId, OpenMode.ForWrite)
       dot.MoveToBottom(OBJid)
    End If
End If

[ed57gmc]

I'm sorry, I'm real busy at the moment and I didn't thoroughly read your code. Thankfully @norman.yuan has you covered.

[ym.56789]

Thanks a lot!