Reading the Block Table of a Dynamic Block

By Augusto Goncalves

For a dynamic block we can create a Block Properties Table, which defines and controls values for parameters and properties. This is available when BEDIT’ing a dynamic block, as shown below.

From the API perspective, this data is stored under a DBDictionary called ACAD_ENHANCEDBLOCK. To access it, we need to use some ‘Internal’ APIs, which means that there is no documentation and it may change.

The following code sample show how to access it for a given selected BlockReference object. Minimal error check were done for simplicity.

[CommandMethod("readBlockTable")]    static public void CmdReadBlockTable()    {      Editor ed = Application.DocumentManager.        MdiActiveDocument.Editor;           // select a block reference      PromptEntityOptions peo = new PromptEntityOptions(        "Select a dynamic block reference: ");      peo.SetRejectMessage("Only block reference");      peo.AddAllowedClass(typeof(BlockReference), false);      PromptEntityResult per = ed.GetEntity(peo);      if (per.Status != PromptStatus.OK) return;      ObjectId blockRefId = per.ObjectId;           // get the database and start a transaction      Database db = Application.DocumentManager.        MdiActiveDocument.Database;      using (Transaction trans = db.        TransactionManager.StartTransaction())      {        // open the dynamic block reference        BlockReference blockRef = trans.GetObject(          blockRefId, OpenMode.ForRead) as BlockReference;        if
 (!blockRef.IsDynamicBlock) return;             // get the dynamic block table definition        BlockTableRecord blockDef = trans.GetObject(          blockRef.DynamicBlockTableRecord,          OpenMode.ForRead) as BlockTableRecord;             // open the extension dictionary        if (blockDef.ExtensionDictionary.IsNull) return;        DBDictionary extDic = trans.GetObject(          blockDef.ExtensionDictionary, OpenMode.ForRead)          as DBDictionary;             // open the ENHANCEDBLOCK dictionary        Autodesk.AutoCAD.Internal.DatabaseServices.EvalGraph graph =          trans.GetObject(extDic.GetAt("ACAD_ENHANCEDBLOCK"),          OpenMode.ForRead) as EvalGraph;             int[] nodeIds = graph.GetAllNodes();        foreach (uint nodeId in nodeIds)        {          // open the node ID          DBObject node = graph.GetNode(nodeId,             OpenMode.ForRead, trans);          // check is if the correct type          if (!(node is BlockPropertiesTable)) continue;          // convert the object          BlockPropertiesTable table =             node as BlockPropertiesTable;               // ok, we have the data, let's show it...               // get the number of columns          int columns = table.Columns.Count;          int currentRow = 0;          foreach (            BlockPropertiesTableRow row            in table.Rows)          {            ed.WriteMessage("n[{0}]:t", currentRow);            for (              int currentColumn = 0;              currentColumn < columns;              currentColumn++)            {              // get the colum value for the               // current row. May be more multiple              TypedValue[] columnValue =                 row[currentColumn].AsArray();              foreach (TypedValue tpVal in columnValue)              {                ed.WriteMessage("{0}; ", tpVal.Value);              }              ed.WriteMessage("|");            }            currentRow++;          }        }      }    }