private static void ChangeInformation()
{
using (var data = new Formula1Entities())
{
var jean = new Racer
{
FirstName = "Jean-Eric",
LastName = "Vergne",
Nationality = "France",
Starts = 0
};
data.Racers.AddObject(jean);
Racer fernando = data.Racers.Where("it.Lastname='Alonso'").First();
fernando.Starts++;
DisplayState(EntityState.Added.ToString(),
data.ObjectStateManager.GetObjectStateEntries(EntityState.Added));
DisplayState(EntityState.Modified.ToString(),
data.ObjectStateManager.GetObjectStateEntries(EntityState.Modified));
ObjectStateEntry stateOfFernando =
data.ObjectStateManager.GetObjectStateEntry(fernando.EntityKey);
Console.WriteLine("state of Fernando: {0}",
stateOfFernando.State.ToString());
foreach (string modifiedProp in stateOfFernando.GetModifiedProperties())
{
Console.WriteLine("modified: {0}", modifiedProp);
Console.WriteLine("original: {0}",
stateOfFernando.OriginalValues[modifiedProp]);
Console.WriteLine("current: {0}",
stateOfFernando.CurrentValues[modifiedProp]);
}
}
}
private static void EagerLoadingDemo()
{
using (var data = new Formula1Entities())
{
foreach (var racer in data.Racers.Include("RaceResults.Race.Circuit"))
{
Console.WriteLine("{0} {1}", racer.FirstName, racer.LastName);
foreach (var raceResult in racer.RaceResults)
{
Console.WriteLine("\t{0} {1:d} {2}", raceResult.Race.Circuit.Name, raceResult.Race.Date, raceResult.Position);
}
}
}
}
private static void DetachDemo()
{
using (var data = new Formula1Entities())
{
data.ObjectStateManager.ObjectStateManagerChanged +=
ObjectStateManager_ObjectStateManagerChanged;
ObjectQuery <Racer> racers = data.Racers.Where("it.Lastname='Alonso'");
Racer fernando = racers.First();
EntityKey key = fernando.EntityKey;
data.Racers.Detach(fernando);
// Racer is now detached and can be changed independent of the
// object context
fernando.Starts++;
Racer originalObject = data.GetObjectByKey(key) as Racer;
data.Racers.ApplyCurrentValues(fernando);
}
}
private static void TrackingDemo()
{
using (var data = new Formula1Entities())
{
data.ObjectStateManager.ObjectStateManagerChanged += ObjectStateManager_ObjectStateManagerChanged;
Racer niki1 = (from r in data.Racers
where r.Nationality == "Austria" && r.LastName == "Lauda"
select r).First();
Racer niki2 = (from r in data.Racers
where r.Nationality == "Austria"
orderby r.Wins descending
select r).First();
if (Object.ReferenceEquals(niki1, niki2))
{
Console.WriteLine("the same object");
}
}
}
