Determine the Parent Object (.NET)

Graphical objects are appended to a BlockTableRecord object, such as Model or Paper space. You reference the blocks that represent Model and Paper space through the BlockTable object. If you want to work in the current space instead of a specific space, you get the ObjectId for the current space from the current database with the CurrentSpaceId property.

The ObjectId for the block table records of Model and Paper space can be retrieved from the BlockTable object using a property or the GetBlockModelSpaceId and GetBlockPaperSpaceId methods of the SymbolUtilityServices class under the DatabaseServices namespace.

Access Model space, Paper space or the current space

The following example demonstrates how to access the block table records associated with Model space, Paper space or the current space. Once the block table record is referenced, a new line is added to the block table record.

C# Example

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.EditorInput;
 
[CommandMethod("AccessSpace")]
public static void AccessSpace()
{
    // Get the current document and database
    Document acDoc = Application.DocumentManager.MdiActiveDocument;
    Database acCurDb = acDoc.Database;

    // Start a transaction
    using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
    {
        // Open the Block table for read
        BlockTable acBlkTbl;
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                     OpenMode.ForRead) as BlockTable;

        // Open the Block table record for read
        BlockTableRecord acBlkTblRec;

        // Request which table record to open
        PromptKeywordOptions pKeyOpts = new PromptKeywordOptions("");
        pKeyOpts.Message = "\nEnter which space to create the line in ";
        pKeyOpts.Keywords.Add("Model");
        pKeyOpts.Keywords.Add("Paper");
        pKeyOpts.Keywords.Add("Current");
        pKeyOpts.AllowNone = false;
        pKeyOpts.AppendKeywordsToMessage = true;

        PromptResult pKeyRes = acDoc.Editor.GetKeywords(pKeyOpts);

        if (pKeyRes.StringResult == "Model")
        {
            // Get the ObjectID for Model space from the Block table
            acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                            OpenMode.ForWrite) as BlockTableRecord;
        }
        else if (pKeyRes.StringResult == "Paper")
        {
            // Get the ObjectID for Paper space from the Block table
            acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.PaperSpace],
                                            OpenMode.ForWrite) as BlockTableRecord;
        }
        else
        {
            // Get the ObjectID for the current space from the database
            acBlkTblRec = acTrans.GetObject(acCurDb.CurrentSpaceId,
                                            OpenMode.ForWrite) as BlockTableRecord;
        }

        // Create a line that starts at 2,5 and ends at 10,7
        using (Line acLine = new Line(new Point3d(2, 5, 0),
                                      new Point3d(10, 7, 0)))
        {
            // Add the new object to the block table record and the transaction
            acBlkTblRec.AppendEntity(acLine);
            acTrans.AddNewlyCreatedDBObject(acLine, true);
        }

        // Save the new line to the database
        acTrans.Commit();
    }
}