Allowing only “required” type of objects during the selection.

By Virupaksha Aithal

You can use “PromptEntityOptions.AddAllowedClass()” API, to allow users to select a particular type of entity during selection. Also you need to set the “SetRejectMessage” message before calling “AddAllowedClass”. For example, below code allows users to select only block references.

[CommandMethod("SelectBlockRef")]
 static public void SelectBlockRef()
 {
     Document doc = Application.DocumentManager.MdiActiveDocument;
     Database db = doc.Database;
     Editor ed = doc.Editor;
 
     PromptEntityOptions options = 
                new PromptEntityOptions("select block reference");
     options.SetRejectMessage(
                          "Select block referencees only" + "n");
     options.AddAllowedClass(typeof(BlockReference), true);
     PromptEntityResult result = ed.GetEntity(options);
 
     if (result.Status != PromptStatus.OK)
         return;
 
     // obtain transaction manager 
     using (Transaction tx = 
                            db.TransactionManager.StartTransaction())
     {
         BlockReference bRef = tx.GetObject(result.ObjectId, 
                                 OpenMode.ForRead) as BlockReference;
         BlockTableRecord block = tx.GetObject(bRef.BlockTableRecord,
                                OpenMode.ForRead) as BlockTableRecord;
         ed.WriteMessage("selected block is :" + block.Name + "n");
         tx.Commit();
     }
 }