You are here: Tuning > Utility Methods > descend

Descend

ExtObjectContainer#descend method allows you to navigate from a persistent object to it's members without activating or instantiating intermediate objects.

UtilityExample.cs: TestDescend
public static void TestDescend()
     {
      StoreSensorPanel();
            IConfiguration configuration = Db4oFactory.NewConfiguration();
            configuration.ActivationDepth(1);
            IObjectContainer db = Db4oFactory.OpenFile(
configuration, Db4oFileName);
      try 
       {
        System.Console.WriteLine("Object container activation depth = 1");
        IObjectSet result = db.QueryByExample(new SensorPanel(1));
        SensorPanel spParent = (SensorPanel)result[0];
        SensorPanel spDescend = (SensorPanel)db.Ext().
Descend((Object)spParent, new String[] {"_next","_next",
"_next","_next","_next"});
        db.Ext().Activate(spDescend, 5);
        System.Console.WriteLine(spDescend);
      } 
      finally 
       {
        db.Close();
      }
    }

UtilityExample.vb: TestDescend
Public Shared Sub TestDescend()
            StoreSensorPanel()
            Dim configuration As IConfiguration = Db4oFactory.NewConfiguration()
            configuration.ActivationDepth(1)
            Dim db As IObjectContainer = Db4oFactory.OpenFile(configuration, _ 
Db4oFileName)
            Try
                System.Console.WriteLine("Object container activation depth = 1")
                Dim result As IObjectSet = db.QueryByExample(New SensorPanel(1))
                Dim spParent As SensorPanel = CType(result(0), SensorPanel)
                Dim fields() As String = {"_next", "_next", "_next", "_next", "_next"}
                Dim spDescend As SensorPanel = CType(db.Ext().Descend( _ 
CType(spParent, Object), fields), Object)
                db.Ext().Activate(spDescend, 5)
                System.Console.WriteLine(spDescend)
            Finally
                db.Close()
            End Try
        End Sub

Navigating in this way can save you resources on activating only the objects you really need.

Download example code:

VB.NET c#