1. Entity Framework Nima?

DbContextTransaction klassi IDisposable interfeysini amalga oshirganligi sababli, tranzaktsiyaning barcha kodi using konstruktoriga olinadi.

Ma’lumotlar bazasi tranzaksiyalar bajarilgandan so‘ng tranzaksiya commiti uchun transaction.Commit() metodi chaqiriladi.

Misolni ko‘rib chiqaylik:

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using(UserContext db = new UserContext()) {     db.Database.Log = Console.Write;                using (var transaction = db.Database.BeginTransaction())     {         try         {  db.Database.ExecuteSqlCommand(@"UPDATE People SET Age=Age+1 WHERE Name = ’Sam’");             db.People.Add(new Person { Age = 34, Name = "Bob" });             db.SaveChanges();             transaction.Commit();         }         catch (Exception ex)         {             transaction.Rollback();         }     }     foreach(Person p in db.People.ToList())         Console.WriteLine("Name: {0}  Age: {1}",p.Name, p.Age); }

Bunday holda, db.Database.ExecuteSqlCommand va db.SaveChanges() metodi ikki xil tranzaksiyani aniqlaydi. Biroq, bu metodlarning ikkalasini ham using (var transaction = db.Database.BeginTransaction()) blokiga olinadi, chunki bu metodlarning ikkalasi ham bitta tranzaksiyaga qo‘shiladi. Agar db.Database.ExecuteSqlCommand  chaqiruvi muvaffaqiyatsiz bo‘lsa, db.SaveChanges() chaqiruvi amalga oshirilmaydi.

Masalan, parallelizm yoki o‘zgartirish yoki qo‘shishda boshqa istisnolardan tashqari, ya’ni tranzaksiyalardan biri (yoki ikkalasi ham) muvaffaqiyatsiz tugasa, ular umuman ma’noga ega bo‘lmaydi. Shuning uchun transaction.Rollback() metodi yordamida barcha o‘zgarishlarni qaytarish kerak bo‘ladi.

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