Start a New Transaction and Open an Object

The Transaction Manager is accessed from the TransactionManager property of the current database. Once a reference to the Transaction Manager is made, you use the StartTransaction method to start a new transaction. StartTransaction creates an instance of a Transaction object and allows you to open objects with the GetObject method.

All open objects opened during a transaction are closed at the end of the transaction. To end a transaction, call the Dispose method of a transaction object. If you use the Using and End Using keywords to indicate the start and end of a transaction, you do not need to call the Dispose method.

Prior to disposing of a transaction, you should commit any changes made with the Commit method. If the changes are not committed before a transaction is disposed, any changes made are rolled back to the state their were in prior to the start of the transaction. For more information on committing or rolling back changes made in a transaction, see Commit and Rollback Changes.

More than one transaction can be started. The number of active transactions can be retrieved with the NumberOfActiveTransactions property of the TransactionManager object while the top most or latest transaction can be retrieved with the TopTransaction property.

Transactions can be nested one inside of another in order to rollback some of the changes made during the execution of a routine. For more information on working with multiple transactions or nesting transactions, see Nest Transactions.

Query objects

The following example demonstrates how to open and read objects within using a transaction. You use the GetObject method to first open the BlockTable and then the Model space record.

VB.NET

Imports Autodesk.AutoCAD.Runtime

Imports Autodesk.AutoCAD.ApplicationServices

Imports Autodesk.AutoCAD.DatabaseServices

<CommandMethod("OpenTransactionManager")> _

Public Sub OpenTransactionManager()

  '' Get the current document and database

  Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument

  Dim acCurDb As Database = acDoc.Database

  '' Start a transaction

  Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()

      '' Open the Block table for read

      Dim acBlkTbl As BlockTable

      acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, OpenMode.ForRead)

      '' Open the Block table record Model space for read

      Dim acBlkTblRec As BlockTableRecord

      acBlkTblRec = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), _

                                      OpenMode.ForRead)

      '' Step through the Block table record

      For Each acObjId As ObjectId In acBlkTblRec

          acDoc.Editor.WriteMessage(vbLf & "DXF name: " & acObjId.ObjectClass().DxfName)

          acDoc.Editor.WriteMessage(vbLf & "ObjectID: " & acObjId.ToString())

          acDoc.Editor.WriteMessage(vbLf & "Handle: " & acObjId.Handle.ToString())

          acDoc.Editor.WriteMessage(vbLf)

      Next

      '' Dispose of the transaction

  End Using

End Sub

using Autodesk.AutoCAD.Runtime;

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.DatabaseServices;

[CommandMethod("OpenTransactionManager")]

public static void OpenTransactionManager()

  // 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 Model space for read

      BlockTableRecord acBlkTblRec;

      acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],

                                      OpenMode.ForRead) as BlockTableRecord;

      // Step through the Block table record

      foreach (ObjectId asObjId in acBlkTblRec)

          acDoc.Editor.WriteMessage("\nDXF name: " + asObjId.ObjectClass.DxfName);

          acDoc.Editor.WriteMessage("\nObjectID: " + asObjId.ToString());

          acDoc.Editor.WriteMessage("\nHandle: " + asObjId.Handle.ToString());

          acDoc.Editor.WriteMessage("\n");

      // Dispose of the transaction

Add a new object to the database

The following example demonstrates how to add a circle object to the database with in a transaction. You use the GetObject method to first open the BlockTable for read and then the Model space record for write. After Model space is opened for write, you use the AppendEntity and AddNewlyCreatedDBObject function to append the new Circle object to Model space as well as the transaction.

VB.NET

Imports Autodesk.AutoCAD.Runtime

Imports Autodesk.AutoCAD.ApplicationServices

Imports Autodesk.AutoCAD.DatabaseServices

Imports Autodesk.AutoCAD.Geometry

<CommandMethod("AddNewCircleTransaction")> _

Public Sub AddNewCircleTransaction()

  '' Get the current document and database

  Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument

  Dim acCurDb As Database = acDoc.Database

  '' Start a transaction

  Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()

      '' Open the Block table for read

      Dim acBlkTbl As BlockTable

      acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, OpenMode.ForRead)

      '' Open the Block table record Model space for write

      Dim acBlkTblRec As BlockTableRecord

      acBlkTblRec = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), _

                                      OpenMode.ForWrite)

      '' Create a circle with a radius of 3 at 5,5

      Dim acCirc As Circle = New Circle()

      acCirc.Center = New Point3d(5, 5, 0)

      acCirc.Radius = 3

      '' Add the new object to Model space and the transaction

      acBlkTblRec.AppendEntity(acCirc)

      acTrans.AddNewlyCreatedDBObject(acCirc, True)

      '' Commit the changes and dispose of the transaction

      acTrans.Commit()

  End Using

End Sub

using Autodesk.AutoCAD.Runtime;

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.DatabaseServices;

using Autodesk.AutoCAD.Geometry;

[CommandMethod("AddNewCircleTransaction")]

public static void AddNewCircleTransaction()

  // 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 Model space for write

      BlockTableRecord acBlkTblRec;

      acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],

                                      OpenMode.ForWrite) as BlockTableRecord;

      // Create a circle with a radius of 3 at 5,5

      Circle acCirc = new Circle();

      acCirc.Center = new Point3d(5, 5, 0);

      acCirc.Radius = 3;

      // Add the new object to Model space and the transaction

      acBlkTblRec.AppendEntity(acCirc);

      acTrans.AddNewlyCreatedDBObject(acCirc, true);

      // Commit the changes and dispose of the transaction

      acTrans.Commit();