//private static void SaveObjects()
//{
// using (var data = new Formula1Entities())
// {
// int changes = 0;
// try
// {
// changes += data.SaveChanges();
// }
// catch (OptimisticConcurrencyException ex)
// {
// data.ChangeTracker.Entries().First().re
// data.Refresh(RefreshMode.ClientWins, ex.StateEntries);
// changes += data.SaveChanges();
// }
// Console.WriteLine("{0} entities changed", changes);
// //...
// catch (DbUpdateConcurrencyException ex)
// {
// saveFailed = true;
// // Update original values from the database
// var entry = ex.Entries.Single();
// entry.OriginalValues.SetValues(entry.GetDatabaseValues());
// }
// catch (DbUpdateConcurrencyException ex)
// {
// saveFailed = true;
// // Get the current entity values and the values in the database
// var entry = ex.Entries.Single();
// var currentValues = entry.CurrentValues;
// var databaseValues = entry.GetDatabaseValues();
// // Choose an initial set of resolved values. In this case we
// // make the default be the values currently in the database.
// var resolvedValues = databaseValues.Clone();
// // Have the user choose what the resolved values should be
// HaveUserResolveConcurrency(currentValues, databaseValues,
// resolvedValues);
// // Update the original values with the database values and
// // the current values with whatever the user choose.
// entry.OriginalValues.SetValues(databaseValues);
// entry.CurrentValues.SetValues(resolvedValues);
// }
// }
//}
private static void DetachingObjects()
{
using (var data = new Formula1Entities())
{
IQueryable <Racer> racers = data.Racers.Where(r => r.LastName == "Alonso").AsNoTracking();
Racer fernando = racers.First();
// Racer is detached and can be changed independent of the
// data context
fernando.Starts++;
ShowTrackedObjects("none tracked", data.ChangeTracker);
//Racer originalObject = data.Racers.Find(fernando.Id);
data.Racers.Attach(fernando);
data.Entry <Racer>(fernando).State = EntityState.Modified;
ShowTrackedObjects("fernando attached", data.ChangeTracker);
//(data as IObjectContextAdapter).ObjectContext.ApplyCurrentValues("Racers", fernando);
//ShowTrackedObjects("apply current", data.ChangeTracker);
}
}
private static void ShowRacersExplicitLoading()
{
using (var data = new Formula1Entities())
{
// data.RaceResults.Load();
foreach (var racer in data.Racers)
{
Console.WriteLine("{0} {1}", racer.FirstName, racer.LastName);
DbCollectionEntry entry = data.Entry(racer).Collection("RaceResults");
if (!entry.IsLoaded)
{
entry.Load();
}
DbCollectionEntry <Racer, RaceResult> entry1 = data.Entry(racer).Collection(r => r.RaceResults);
if (!entry1.IsLoaded)
{
entry1.Load();
}
//if (!data.Entry(racer).Collection("RaceResults").IsLoaded)
//{
// data.Entry(racer).Collection("RaceResults").Load();
//}
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 ReadRecord()
{
using (var data = new Formula1Entities())
{
Racer r1 = data.Racers.Where(r => r.LastName == "Alonso").First();
Console.WriteLine("after the update, the new value is {0}", r1.Starts);
}
}
private static void ShowRacersEagerLoading()
{
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 DbSqlQuerySample()
{
using (Formula1Entities data = new Formula1Entities())
{
data.Database.Log = Console.Write;
string country = "Brazil";
// DbSqlQuery<Racer> racers = data.Racers.SqlQuery("SELECT * FROM Racers WHERE nationality = @country", new SqlParameter("country", country));
DbSqlQuery <Racer> racers = data.Racers.SqlQuery("SELECT * FROM Racers WHERE nationality = @p0", country).AsNoTracking();
foreach (var r in racers)
{
Console.WriteLine("{0} {1}", r.FirstName, r.LastName);
}
}
}
private static void LinqToEntities1()
{
using (Formula1Entities data = new Formula1Entities())
{
data.Database.Log = Console.Write;
var racers = from r in data.Racers
where r.Wins > 40
orderby r.Wins descending
select r;
foreach (Racer r in racers)
{
Console.WriteLine("{0} {1}", r.FirstName, r.LastName);
}
}
}
private static void TrackingDemo()
{
using (var data = new Formula1Entities())
{
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");
}
}
}
private static void ShowRacers()
{
using (var data = new Formula1Entities())
{
data.Database.Log = Console.WriteLine;
foreach (var racer in data.Racers)
{
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 async static Task UserSaveObjectLastWins(string user, int delay, int starts)
{
using (var data = new Formula1Entities())
{
int changes = 0;
try
{
Racer r1 = data.Racers.Where(r => r.LastName == "Alonso").First();
r1.Starts = starts;
await Task.Delay(delay);
changes = data.SaveChanges();
}
catch (DbUpdateConcurrencyException ex)
{
Console.WriteLine("{0} error {1}", user, ex.Message);
}
Console.WriteLine("{0} changed {1} record(s)", user, changes);
}
}
private async static Task UserDealWithUpdates(string user, int delay, int starts)
{
using (var data = new Formula1Entities())
{
int changes = 0;
bool saveFailed = false;
do
{
try
{
saveFailed = false;
Racer r1 = data.Racers.Where(r => r.LastName == "Alonso").First();
r1.Starts = starts;
await Task.Delay(delay);
changes = data.SaveChanges();
}
catch (DbUpdateConcurrencyException ex)
{
saveFailed = true;
Console.WriteLine("{0} error {1}", user, ex.Message);
foreach (var entry in ex.Entries)
{
DbPropertyValues currentValues = entry.CurrentValues;
DbPropertyValues databaseValues = entry.GetDatabaseValues();
DbPropertyValues resolvedValues = databaseValues.Clone();
AskUser(currentValues, databaseValues, resolvedValues);
entry.OriginalValues.SetValues(databaseValues);
entry.CurrentValues.SetValues(resolvedValues);
}
}
}while (saveFailed);
Console.WriteLine("{0} changed {1} record(s)", user, changes);
}
}
private static void ChangeInformation()
{
using (var data = new Formula1Entities())
{
var esteban = data.Racers.Create();
esteban.FirstName = "Esteban";
esteban.LastName = "Gutierrez";
esteban.Nationality = "Mexico";
esteban.Starts = 0;
data.Racers.Add(esteban);
Racer fernando = data.Racers.Where(r => r.LastName == "Alonso").First();
fernando.Wins++;
fernando.Starts++;
foreach (DbEntityEntry <Racer> entry in data.ChangeTracker.Entries <Racer>())
{
Console.WriteLine("{0}, state: {1}", entry.Entity, entry.State);
if (entry.State == EntityState.Modified)
{
Console.WriteLine("Original values");
DbPropertyValues values = entry.OriginalValues;
foreach (string propName in values.PropertyNames)
{
Console.WriteLine("{0} {1}", propName, values[propName]);
}
Console.WriteLine();
Console.WriteLine("Current values");
values = entry.CurrentValues;
foreach (string propName in values.PropertyNames)
{
Console.WriteLine("{0} {1}", propName, values[propName]);
}
}
}
}
}
private static void LinqToEntities2()
{
using (var data = new Formula1Entities())
{
var query = from r in data.Racers
from rr in r.RaceResults
where rr.Position <= 3 && rr.Position >= 1 &&
r.Nationality == "Switzerland"
group r by r.Id into g
let podium = g.Count()
orderby podium descending
select new
{
Racer = g.FirstOrDefault(),
Podiums = podium
};
foreach (var r in query)
{
Console.WriteLine("{0} {1} {2}", r.Racer.FirstName, r.Racer.LastName,
r.Podiums);
}
}
}
