Entity Framework

[Heidel]

Добавить несколько записей в БД (EF6)

context.Ninjas.AddRange(new List<Ninja> { ninja1, ninja2 });
context.SaveChanges();

Простые запросы

using (var context = new NinjaContext())
{
	var ninjas = context.Ninjas.ToList();
	
	
	var query = context.Ninjas;
	foreach (var ninja in query)
	{
		Console.WriteLine(ninja.Name)
	}
	
	
	foreach (var ninja in context.Ninjas)
	{
		Console.WriteLine(ninja.Name)
	}
	
	// LINQ Methods
	var ninjas = context.Ninjas.Where(n=>n.Name=="Raphael");
	foreach (var ninja in ninjas)
	{
		Console.WriteLine(ninja.Name)
	}
	
	
	var ninjas = context.Ninjas.Where(n=>n.DateOfBirth>=new DateTime(1984,1,1));
	foreach (var ninja in ninjas)
	{
		Console.WriteLine(ninja.Name)
	}
	
	// FirstOrDefault() возвращает единственный результат
	var ninja = context.Ninjas.Where(n=>n.DateOfBirth>=new DateTime(1984,1,1))
	.FirstOrDefault();
	Console.WriteLine(ninja.Name);
	
	
	var ninja = context.Ninjas.Where(n=>n.DateOfBirth>=new DateTime(1984,1,1))
	.OrderBy(n=>n.Name)
	.Skip(1).Take(1)
	.FirstOrDefault();
}

Updating Modified Objects

using (var context = new NinjaContext())
{
	var ninja = context.Ninjas.FirstOrDefaul();
	ninja.ServedInOniwaban = (!ninja.ServedInOniwaban);
	context.SaveChanges();
}

Find and Sql Methods

var keyval = 4;
using (var context = new NinjaContext())
{
	var ninja = context.Ninjas.Find(keyval);	
}


using (var context = new NinjaContext())
{
	var ninjas = context.Ninjas.SqlQuery("exec GetOldNinjas");
	foreach (var ninja in ninjas)
	{
		Console.WriteLine(ninja.Name)
	}
}

Файл dbo.GetOldNinjas.sql
CREATE PROCEDURE GetOldNinjas
                        AS
						SELECT * FROM Ninjas WHERE DateOfBirth<= '1/1/1980'
						
using (var context = new NinjaContext())
{
	var ninjas = context.Ninjas.SqlQuery("exec GetOldNinjas").ToList();
}

Deleting Simple Object

using (var context = new NinjaContext())
{
	var ninja = context.Ninjas.FirstOrDefaul();
	context.Ninjas.Remove(ninja);
	context.SaveChanges();
}

using (var context = new NinjaContext())
{
	var ninja = context.Ninjas.FirstOrDefaul();
	context.Entry(ninja).State = EntityState.Deleted;
	context.SaveChanges();
}

var keyval = 1;
using (var context = new NinjaContext())
{
	var ninja = context.Ninjas.Find(keyval);
	context.Ninjas.Remove(ninja);
	context.SaveChanges();
}

var keyval = 3;
using (var context = new NinjaContext())
{
	context.Database.ExecuteSqlCommand("exec DeleteNinjaViaId {0}", keyval);
}

Inserting Related Data

using (var context = new NinjaContext())
{
	var ninja = new Ninja
	{
		Name = "Kacy Catanzaro";
		ServedInOniwaban = false;
		DateOfBirth = new DateTime(1990,1,14),
		ClanId = 1
	};
	var muscules = new NinjaEquipment
	{
		Name = "Muscules";
		Type = EquipmentType.Tool,
	};
	var spunk = new NinjaEquipment
	{
		Name = "Spunk";
		Type = EquipmentType.Weapon,
	};
	context.Ninjas.Add(ninja);
	ninja.EquipmentOwned.Add(muscules);
	ninja.EquipmentOwned.Add(spunk);
	context.SaveChanges();
}

Loading Related Data
DbSet.Include() метод

// Eager Loading
using (var context = new NinjaContext())
{
	var ninja = context.Ninjas.Include(n=>n.EquipmentOwned).FirstOrDefault(n=>n.Name.StartWith("Kacy"));
}

// Explicit Loading
using (var context = new NinjaContext())
{
	var ninja = context.Ninjas.FirstOrDefault(n=>n.Name.StartWith("Kacy"));
	context.Entry(ninja).Collection(n => n.EquipmentOwned).Load();
}

// Lazy Loading		
// пометить свойство в модели как virtual

// Projection
// Select method
using (var context = new NinjaContext())
{
	var ninja = context.Ninjas
	.Select(n => new { n.Name, n.DateOfBirth, n.EquipmentOwned })
	.ToList();
}

@темы: БД, ASP.NET MVC, Entity Framework