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Dasturiy injiniring (EntityFramework 6)
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| bet | 27/53 | | Sana | 30.11.2023 | | Hajmi | 1,39 Mb. | | #108476 |
Bog'liq Dasturiy injiniringLINQ to Entities so’rovlarini tavsiflashdan avval ushbu bo’lim uchun zarur bo’lgan modellarni aniqlab olamiz:
class Company
{
public int Id { get; set; }
public string Name { get; set; }
public ICollection Phones { get; set; }
public Company()
{
Phones = new List();
}
}
class Phone
{
public int Id { get; set; }
public string Name { get; set; }
public int Price { get; set; }
public int CompanyId { get; set; }
public Company Company { get; set; }
}
Yuqorida telefon va ishlab chiquvchi kompaniya modeli keltirilgan. Endi ushbu modellarga mos ma’lumotlar konteksti va DB initsializatori orqali boshlang‘ich ma’lumotlarni shakllantiramiz.
class PhoneContext : DbContext
{
static PhoneContext()
{
Database.SetInitializer(new MyContextInitializer());
}
public PhoneContext()
: base("DBConnection")
{ }
public DbSet Companies { get; set; }
public DbSet Phones { get; set; }
}
class MyContextInitializer : DropCreateDatabaseAlways
{
protected override void Seed(PhoneContext db)
{
Company c1 = new Company { Name = "Samsung" };
Company c2 = new Company { Name = "Apple" };
db.Companies.Add(c1);
db.Companies.Add(c2);
db.SaveChanges();
Phone p1 = new Phone { Name = "Samsung Galaxy S5", Price = 20000, Company = c1 };
Phone p2 = new Phone { Name = "Samsung Galaxy S4", Price = 15000, Company = c1 };
Phone p3 = new Phone { Name = "iPhone5", Price = 28000, Company = c2 };
Phone p4 = new Phone { Name = "iPhone 4S", Price = 23000, Company = c2 };
db.Phones.AddRange(new List() { p1, p2, p3, p4 });
db.SaveChanges();
}
}
So’ngra App.config faylida ulanish satri hosil qilish lozim:
DBda boshlang‘ich ma’lumotlarni shakllantirish uchun initsializatorda bir nechta ob’ektlar hosil qilinadi. Initsializatorni ishga tushirish uchun u ma’lumotlar kontekstidagi statik konstruktorda chaqiriladi:
static PhoneContext()
{
Database.SetInitializer(new MyContextInitializer());
}
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