Listing attributes of a .dwg file via C# throws "Common Language Runtime detected an invalid program"

Question

I'm trying to list block attributes inside a .dwg file and save them in my database, here is the code I'm using:

using Autodesk.AutoCAD.DatabaseServices;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;

namespace CSP1257.Helpers
{
    public class AutocadHelper
    {

        public static Dictionary<string,string> ListAttributes(string dwgFile)
        {
            Dictionary<string, string> ret = new Dictionary<string, string>();

            using (Database attDb = new Database(false, true))
            {
                attDb.ReadDwgFile(dwgFile, FileShare.ReadWrite, false, null);
                Transaction tr = attDb.TransactionManager.StartTransaction();
                BlockTable bt = (BlockTable)attDb.BlockTableId.GetObject(OpenMode.ForRead);
                BlockTableRecord mBtr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForRead);

                foreach (ObjectId msId in mBtr)
                {
                    BlockReference blkRef = (BlockReference)tr.GetObject(msId, OpenMode.ForRead);
                    AttributeCollection atts = blkRef.AttributeCollection;
                    if (atts == null)
                        continue;

                    foreach (ObjectId arId in atts)
                    {
                        AttributeReference attRef = (AttributeReference)tr.GetObject(arId, OpenMode.ForRead);
                        ret.Add(attRef.Tag, attRef.TextString);
                    }
                }
            }

            return ret;
        }
    }
}

However I'm getting this exception:

Common Language Runtime detected an invalid program.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.InvalidProgramException: Common Language Runtime detected an invalid program.

Source Error:     
Line 20:                 Transaction tr = attDb.TransactionManager.StartTransaction();

I'm not sure why I'm getting this exception though, and is there another way to achieve the same result ?

That is quite a gross mishap, pretty unlikely that Autodesk would release an assembly with such a bug. You'll have to consider that the file got corrupted. Use another machine, check the disk drive, copy the file again, that sort of thing. — Hans Passant, Aug 15 '16 at 10:10
Hmya, and you are sure you are not just copying the same corrupted file to all of them? Contact Autodesk for support. — Hans Passant, Aug 15 '16 at 10:30
are you calling this from a .DLL (AutoCAD plugin) or from a .EXE (Windows Application)? — Augusto Goncalves, Aug 15 '16 at 13:03
It's a .dll added to an MVC5 Web application via Nuget package manager — Mahmoud Aladdin, Aug 17 '16 at 08:22
Are you copying the acmgd.dll and acdbmgd.dll files over? This could cause problems. — Parrish Husband, Aug 17 '16 at 13:36
They already exist in my project assemblies, do I need to copy them somewhere else ? — Mahmoud Aladdin, Aug 18 '16 at 09:19
hello - did you manage to find a solution to the above problem? — BenKoshy, Mar 22 '17 at 22:29

Alain · Answer 1 · 2016-08-19T10:01:27.053

Update:

The error occurs in the cast, so we need to check like something like this:

 DBObject obj = tr.GetObject(msId, OpenMode.ForRead);

                if (obj.GetType() != typeof(BlockReference)) continue;

                BlockReference blkRef = obj as BlockReference;

I think here's the problem: BlockReference blkRef = (BlockReference)tr.GetObject(msId, OpenMode.ForRead);

You are casting every object in modelspace to a block, but there could also be a line in model space. Then in the next line your trying to get the attribute collection of a line. Which is not possible.

So the solution is to check if BlkRef == null in that case just skip it.

if (BlkRef == null) continue;

Listing attributes of a .dwg file via C# throws "Common Language Runtime detected an invalid program"

1 Answers1