private static void Find(int id)
{
using (var context = new AutoLotDbContext())
{
//Find search in DbChangeTracker first and then in Db
Console.WriteLine(context.Cars.Find(id));
}
}
private static void RemoveMultipleRecords(IEnumerable<Car> carsToRemove)
{
using (var context = new AutoLotDbContext())
{
context.Cars.RemoveRange(carsToRemove);
context.SaveChanges();
}
}
private static void AddNewRecords(IEnumerable<Car> carsToAdd)
{
using (var context = new AutoLotDbContext())
{
context.Cars.AddRange(carsToAdd);
context.SaveChanges();
}
}
private static void PrintAllInventory()
{
using (var context = new AutoLotDbContext())
{
foreach (var c in context.Cars.Where(x => x.Make == "BMW"))
{
Console.WriteLine(c);
}
}
}
private static void GetShortCars()
{
using (var context = new AutoLotDbContext())
{
//entities from Database calls remains untracked
foreach (var c in context.Database.SqlQuery(typeof(ShortCar), "Select CarId, Make from dbo.Inventory"))
{
Console.WriteLine(c);
}
}
}
private static void ChainingLinqQueries()
{
using (var context = new AutoLotDbContext())
{
var allData = context.Cars;
var colorsMakes = from item in allData select new { item.Color, item.Make };
foreach (var item in colorsMakes)
{
Console.WriteLine(item);
}
}
}
private static void UpdateRecord(int carId)
{
using (var context = new AutoLotDbContext())
{
var carToUpdate = context.Cars.Find(carId);
if (carToUpdate != null)
{
Console.WriteLine(context.Entry(carToUpdate).State);
carToUpdate.Color = "Blue";
Console.WriteLine(context.Entry(carToUpdate).State);
context.SaveChanges();
}
}
}
private static void RemoveRecord(int carId)
{
using (var context = new AutoLotDbContext())
{
var carToDelete = context.Cars.Find(carId); //first load entity and then delete it
if (carToDelete != null)
{
context.Cars.Remove(carToDelete);
}
Console.WriteLine(context.Entry(carToDelete).State); //Deleted
context.SaveChanges();
}
}
private static void EagerLoading()
{
using (var context = new AutoLotDbContext())
{
context.Configuration.LazyLoadingEnabled = false; //doesn't matter, we loaded all we need
foreach (var car in context.Cars.Include("Orders"))
{
foreach (var order in car.Orders)
{
Console.WriteLine(order.OrderId);
}
}
}
}
private static void LazyLoading()
{
using (var context = new AutoLotDbContext())
{
context.Configuration.LazyLoadingEnabled = true; //by default
foreach (var car in context.Cars)
{
//will hit database many times
foreach (var order in car.Orders)
{
Console.WriteLine(order.OrderId);
}
}
}
}
private static void RemoveRecordUsingEntityState(int carId)
{
using (var context = new AutoLotDbContext())
{
var carToDelete = new Car{ CarId = carId };
//var car = context.Cars.Find(carId); //to fail
context.Entry(carToDelete).State = EntityState.Deleted; //will fail if item with the same key already tracked
try
{
context.SaveChanges();
}
catch (DbUpdateConcurrencyException ex) //will fail if no entity with such Id
{
Console.WriteLine(ex);
}
}
}
private static int AddNewRecord()
{
using (var context = new AutoLotDbContext())
{
try
{
var car = new Car{ Make = "Yugo", Color = "Brown", CarNickName = "Brownie" };
context.Cars.Add(car);
context.SaveChanges();
return car.CarId;
}
catch (Exception ex)
{
Console.WriteLine(ex.InnerException?.Message);
return 0;
}
}
}
private static void ExplicitLoading()
{
using (var context = new AutoLotDbContext())
{
context.Configuration.LazyLoadingEnabled = false; //to guarantee nothing more loaded
foreach (var car in context.Cars)
{
context.Entry(car).Collection(x => x.Orders).Load();
foreach (var order in car.Orders)
{
Console.WriteLine(order.OrderId);
}
}
foreach (var order in context.Orders)
{
context.Entry(order).Reference(x => x.Car).Load();
}
}
}
public BaseRepo()
{
//context recreation is a costly operation, need to see in particular case how to share it
_ctx = new AutoLotDbContext();
_table = _ctx.Set <T>();
}
