public void Solution10B()
{
const string sql = @"update Devices
set Firmware = '9.9.9.9'
where Model = 'SL2600'";
const string deleteSql = @"delete from Contacts where Id = 2011";
int contactId = 2011;
using (var context = new RadioContext())
using (var context2 = new RadioContext(context.Database.Connection))
using (var transaction = context.Database.BeginTransaction())
{
// context 2
context2.Database.UseTransaction(transaction.UnderlyingTransaction);
Contact contact = context2.Contacts.Find(contactId);
contact.Country = "Poland";
context2.SaveChanges();
// context 1
context.Database.ExecuteSqlCommand(deleteSql);
context.Contacts.Remove(contact);
context.SaveChanges();
transaction.Commit();
}
}
public void Example4B()
{
var myDevice = new Device {
Id = 99999, Name = "My Radio"
};
using (var context = new RadioContext())
{
context.Configuration.AutoDetectChangesEnabled = true; // domyślnie włączone
context.Devices.Add(myDevice);
var entities = context.ChangeTracker.Entries();
Device device = context.Devices.AsNoTracking().First();
entities = context.ChangeTracker.Entries();
device.Firmware = "10.0.0.0";
WriteOutput($"{context.Entry(myDevice).State}");
WriteOutput($"{context.Entry(device).State}");
device.Firmware = "10.0.0.0";
WriteOutput($"{context.Entry(device).State}");
}
}
private StepConfiguration LoadContext(RadioContext context)
{
Step step = new Step(context);
handler.Steps.Add(step);
return(new StepConfiguration(step));
}
public void Example13()
{
using (var context = new RadioContext())
{
context.Database.Log += msg
=> WriteOutput(msg, ConsoleColor.Green);
// note: using System.Data.Entity;
var calls = context.Calls
.Include(p => p.Source)
.Include(p => p.Sender)
.AsNoTracking()
.Select(c => new
{
c.Id,
c.Status,
c.Source.Model,
c.Source.Firmware,
c.Sender.Country,
c.Sender.CompanyName
})
.ToList();
}
}
public void Example6()
{
int userId = 2009;
string firstName = "Marcin";
string lastName = "Sulecki";
using (var context = new RadioContext())
{
User user = context.Contacts
.OfType <User>()
.Single(c => c.Id == userId);
WriteOutput(context.Entry(user).State.ToString());
user.FirstName = firstName;
user.LastName = lastName;
WriteOutput(context.Entry(user).State.ToString());
context.SaveChanges();
WriteOutput(context.Entry(user).State.ToString());
user.Country = "Poland";
WriteOutput(context.Entry(user).State.ToString());
context.SaveChanges();
WriteOutput(context.Entry(user).State.ToString());
}
}
public void Solution11B()
{
int deviceId = 1001;
using (var context1 = new RadioContext())
using (var context2 = new RadioContext())
{
context1.Database.Log += msg => WriteOutput(msg, ConsoleColor.Green);
context2.Database.Log += msg => WriteOutput(msg, ConsoleColor.Blue);
Random random = new Random();
// user 1
var device1 = context1.Devices.Find(deviceId);
device1.Model = $"DP {random.Next(1, 100)}";
try
{
// user 2
var device2 = context2.Devices.Find(deviceId);
device2.Firmware = $"1.0.0.{random.Next(1, 10)}";
context2.SaveChanges();
// user 1
context1.SaveChanges();
}
catch (DbUpdateConcurrencyException e)
{
WriteOutput("Another user was changed data", ConsoleColor.Red);
}
}
}
public void Solution12()
{
UserSearchCriteria criteria = new UserSearchCriteria
{
Country = "Poland"
};
using (var context = new RadioContext())
{
context.Database.Log += msg => WriteOutput(msg, ConsoleColor.Green);
IQueryable <User> contacts = context.Contacts.OfType <User>();
if (!string.IsNullOrEmpty(criteria.FirstName))
{
contacts = contacts.Where(c => c.FirstName == criteria.FirstName);
}
if (!string.IsNullOrEmpty(criteria.LastName))
{
contacts = contacts.Where(c => c.LastName == criteria.LastName);
}
if (!string.IsNullOrEmpty(criteria.Country))
{
contacts = contacts.Where(c => c.Country == criteria.Country);
}
List <User> filteredUsers = contacts.Take(100).ToList();
}
}
public void Example2()
{
string model = "SL2600";
using (var context = new RadioContext())
{
context.Configuration.LazyLoadingEnabled = true;
context.Configuration.ProxyCreationEnabled = true;
IQueryable <Device> devices = context.Devices
.Where(d => d.Model == model);
List <Device> myDevices = devices.ToList();
foreach (var device in myDevices)
{
// Następuje niepożądane zjawisko - dla każdej encji wykonywane jest zapytanie do bazy danych
int qty = device.Calls.Count;
// WriteOutput($"{device.Name} - {device.Calls.Count}");
}
context.Configuration.LazyLoadingEnabled = false;
context.Configuration.ProxyCreationEnabled = false;
}
}
public void Solution4B()
{
var myDevice = new Device {
Id = 99999, Name = "My Radio"
};
using (var context = new RadioContext())
{
try
{
context.Configuration.AutoDetectChangesEnabled = false;
context.Devices.Add(myDevice);
var entities = context.ChangeTracker.Entries();
Device device = context.Devices.AsNoTracking().First();
entities = context.ChangeTracker.Entries();
device.Firmware = "10.0.0.0";
WriteOutput($"{context.Entry(myDevice).State}");
WriteOutput($"{context.Entry(device).State}");
device.Firmware = "10.0.0.0";
WriteOutput($"{context.Entry(device).State}");
}
finally
{
context.Configuration.AutoDetectChangesEnabled = true;
}
}
}
public void Solution9B()
{
string country = "Poland";
var config = new MapperConfiguration(
cfg => cfg.CreateMap <User, UserDTO>()
.ForMember(dest => dest.Surname, opt => opt.MapFrom(src => src.LastName)));
var mapper = config.CreateMapper();
using (var context = new RadioContext())
{
IQueryable <UserDTO> users = context.Contacts
.OfType <User>()
.Where(u => u.Country == country)
.ProjectTo <UserDTO>(config)
.OrderBy(u => u.Surname);
List <UserDTO> userDTOs = users.ToList();
var userDTO = userDTOs.First();
WriteOutput(context.Entry(userDTO).State.ToString());
}
}
public void Solution9C()
{
string model = "DP2000e";
var config = new MapperConfiguration(
cfg => cfg.CreateMap <Device, DeviceDTO>()
.ForMember(dest => dest.FullName,
opt => opt.MapFrom(src => src.Model + " " + src.Firmware))
.ForMember(dest => dest.CallCount,
opt => opt.MapFrom(src => src.Calls.Count))
);
var mapper = config.CreateMapper();
using (var context = new RadioContext())
{
IQueryable <DeviceDTO> deviceDTOs = context.Devices
.Where(d => d.Model == model)
.ProjectTo <DeviceDTO>(config)
.OrderBy(d => d.CallCount);
List <DeviceDTO> devices = deviceDTOs.ToList();
}
}
// Usuwanie encji z użyciem metody rozszerzacącej na DbContext
public void Solution6D()
{
int userId = 1000;
using (var context = new RadioContext())
{
context.Remove <User>(userId);
context.SaveChanges();
}
}
public void Example4A()
{
using (var context = new RadioContext())
{
Device device = context.Devices.First();
// Wyświetlenie stacji encji
WriteOutput($"{context.Entry(device).State}");
}
}
public void Example1()
{
string model = "SL2600";
using (var context = new RadioContext())
{
List <Device> devices = context.Devices.ToList(); // Pobieramy wszystkie urządzenia
List <Device> myDevices = devices.Where(d => d.Model == model).ToList(); // Filtrujemy dopiero po stronie klienta
}
}
// Usuwanie encji z użyciem metody rozszerzacącej na DbSet
public void Solution6E()
{
int deviceId = 1000;
using (var context = new RadioContext())
{
context.Devices.Remove(deviceId);
context.SaveChanges();
}
}
public void Solution2B()
{
string model = "SL2600";
using (var context = new RadioContext())
{
List <Device> popularDevices = context.Devices
.Where(d => d.Model == model)
.Where(d => d.Calls.Count > 100)
.ToList();
}
}
public void Solution4A()
{
using (var context = new RadioContext())
{
Device device = context
.Devices
.AsNoTracking() // wyłączenie śledzenie zmian
.First();
WriteOutput($"{context.Entry(device).State}");
}
}
// Query Syntax
public void Solution1C()
{
string model = "SL2600";
using (var context = new RadioContext())
{
List <Device> myDevices = (from d in context.Devices
where d.Model == model
select d) // utworzenie wyrażenia
.ToList(); // materializacja
}
}
// Method Syntax
public void Solution1B()
{
string model = "SL2600";
using (var context = new RadioContext())
{
IQueryable <Device> devices = context
.Devices
.Where(d => d.Model == model); // utworzenie wyrażenia
List <Device> myDevices = devices.ToList(); // materializacja
}
}
public void Example8()
{
int userId = 2004;
using (var context = new RadioContext())
{
User user = context.Contacts.OfType <User>().Single(u => u.Id == userId);
context.Contacts.Remove(user);
context.SaveChanges();
}
}
// Usuwanie encji za pomocą bezpośredniej zmiany stanu
public void Solution6C()
{
int userId = 1000;
User user = new User {
Id = userId
};
using (var context = new RadioContext())
{
context.Contacts.Attach(user);
context.Entry(user).State = EntityState.Deleted;
context.SaveChanges();
}
}
public void Solution6A()
{
int userId = 2009;
string firstName = "Bartek";
string lastName = "Sulecki";
using (var context = new RadioContext())
{
context.Configuration.AutoDetectChangesEnabled = false;
User user = context.Contacts
.AsNoTracking()
.OfType <User>()
.Single(c => c.Id == userId);
// TODO: Long process
WriteOutput(context.Entry(user).State.ToString());
context.Contacts.Attach(user);
user.FirstName = firstName;
user.LastName = lastName;
WriteOutput(context.Entry(user).State.ToString());
WriteOutput(context.Entry(user).State.ToString());
context.ChangeTracker.DetectChanges();
WriteOutput(context.Entry(user).State.ToString());
context.SaveChanges();
WriteOutput(context.Entry(user).State.ToString());
user.Country = "Poland";
WriteOutput(context.Entry(user).State.ToString());
context.SaveChanges();
WriteOutput(context.Entry(user).State.ToString());
}
}
public void Example3()
{
string model = "SL2600";
using (var context = new RadioContext())
{
List <Device> devices = context.Devices
.Where(d => d.Model == model)
.ToList();
foreach (var device in devices)
{
WriteOutput($"{device.Name} {device.Firmware}");
}
}
}
public void Solution1A()
{
string model = "SL2600";
using (var context = new RadioContext())
{
// Podpięcie się pod zdarzenie materializacji
// DbContext tego nie upublicznia dlatego wymagane jest pobranie ObjectContext)
context.GetObjectContext().ObjectMaterialized += (s, e) => WriteOutput($"Object materialized {e.Entity}", ConsoleColor.DarkMagenta);
List <Device> myDevices = context
.Devices
.Where(d => d.Model == model) // utworzenie wyrażenia
.ToList(); // materializacja
}
}
public void Example9()
{
string country = "Poland";
using (var context = new RadioContext())
{
List <UserDTO> users = context.Contacts
.OfType <User>()
.Where(u => u.Country == country)
.Select(u => new UserDTO
{
FirstName = u.FirstName,
Surname = u.LastName
})
.ToList();
}
}
public void Solution3()
{
string model = "SL2600";
using (var context = new RadioContext())
{
var devices = context.Devices
.Where(d => d.Model == model)
.Select(d => new { d.Name, d.Firmware })
.ToList();
foreach (var device in devices)
{
WriteOutput($"{device.Name} {device.Firmware}");
}
}
}
public void Example14()
{
var model = new Model {
Page = 2, ResultsPerPage = 10
};
using (var context = new RadioContext())
{
context.Database.Log += msg => WriteOutput(msg, ConsoleColor.Red);
List <Device> devices = context.Devices
.OrderBy(d => d.Model)
.Skip(model.Page * model.ResultsPerPage)
.Take(model.ResultsPerPage)
.ToList();
}
}
public void Example6C()
{
int userId = 2008;
using (var context = new RadioContext())
{
User user = context.Contacts.OfType <User>().Single(u => u.Id == userId);
// User user = context.Contacts.Include(c=>c.Calls).OfType<User>().Single(u => u.Id == userId);
context.Contacts.Remove(user);
var entities = context.ChangeTracker.Entries();
context.SaveChanges();
}
}
public void Example11()
{
using (var context1 = new RadioContext())
using (var context2 = new RadioContext())
{
// user 1
var contact1 = context1.Contacts.Find(contactId);
contact1.CompanyName = "Altkom 2";
// user 2
var contact2 = context1.Contacts.Find(contactId);
contact2.CompanyName = "Motorola 2";
context2.SaveChanges();
// user 1
context1.SaveChanges();
}
}
// PM> Install-Package AutoMapper
public void Solution9A()
{
string country = "Poland";
var config = new MapperConfiguration(
cfg => cfg.CreateMap <User, UserDTO>()
.ForMember(dest => dest.Surname, opt => opt.MapFrom(src => src.LastName)));
var mapper = config.CreateMapper();
using (var context = new RadioContext())
{
IQueryable <User> users = context.Contacts
.OfType <User>()
.Where(u => u.Country == country);
List <UserDTO> userDTOs = mapper.Map <List <UserDTO> >(users);
}
}