JLS3

[jlsantiago]

How to get the ObjectId of an existing block in c#

[Hallex]

Do you want to get ObjectId of BlockReferece (graphical instance of Block Definition)

 or of Block Definition itself?

There is a two different objects btw

[Hallex · Accepted solution]

Hetre is quick code hope this will  make a sence

       [CommandMethod("testblock")]
        public static void TestBlocks()
        {
            string blockName = "dyn";
            Document doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
            Editor ed = doc.Editor;
            Database db = HostApplicationServices.WorkingDatabase;
             Transaction tr = db.TransactionManager.StartTransaction();

             using (tr)
             {
                 try
                 {
                     BlockTable bt = tr.GetObject(db.BlockTableId, OpenMode.ForRead) as BlockTable;
                     if (!bt.Has(blockName))
                     {
                         ed.WriteMessage("\nBlock \"{0}\" does not exist", blockName);
                         return;
                     }
                     
                     ObjectId blkID = bt[blockName];
                     ed.WriteMessage("\nBlock \"{0}\" does exist, ObjectId is: {1}", blockName, blkID);
                     
                     BlockTableRecord btr = tr.GetObject(bt[blockName], OpenMode.ForRead) as BlockTableRecord;


                     ObjectIdCollection blkRefIds = btr.GetBlockReferenceIds(true, false);

                     if (blkRefIds.Count == 0)
                     {
                         ed.WriteMessage("\nNo block instances \"{0}\" found", blockName);
                         return;
                     }
                     foreach (ObjectId brefId in blkRefIds)
                     {
                         BlockReference blkRef = (BlockReference)tr.GetObject(brefId, OpenMode.ForRead, false) as BlockReference;      
                         ed.WriteMessage("\nBlock Reference \"{0}\" with ObjectID {1} found  at position: {2}", blkRef.Name, brefId,blkRef.Position);

                     }
                     tr.Commit();//optional in this context
                 }
                 catch (Autodesk.AutoCAD.Runtime.Exception ex)
                 {
                     ed.WriteMessage(("AutoCAD Exception: " + ex.Message));

                 }
                 catch (System.Exception ex)
                 {
                     ed.WriteMessage(("Sytem Exception: " + ex.Message));

                 }
                 finally
                 {
                     // optional
                 }
             }
			}

~'J'~