Administrator paneli: kataloglarni boshqarish

Saqlash hajmi kengaytirish

Web-fromaga funktsiyalarni qo'shishni boshlashdan oldin ma'lumotlar bazasida mahsulot yozuvlarini qo'shish, o'zgartirish va o'chirish uchun saqlash sinfini kengaytirishimiz kerak. Quyidagi misolda \ Models \ Repository \ Repository.cs faylidan Repository sinfiga qo'shiladigan SaveGame () va DeleteGame () usullarining ta'rifi ko'rsatilgan:

C#

using System.Collections.Generic;

using System.Data.Entity;

using System.Linq;

namespace GameStore.Models.Repository

{

public class Repository

{

private EFDbContext context = new EFDbContext();

public IEnumerable Games

{

// ...

}
public IEnumerable Orders

{

// ...

}
public void SaveGame(Game game)

{

if (game.GameId == 0)

{

game = context.Games.Add(game);

}

else

{

Game dbGame = context.Games.Find(game.GameId);

if (dbGame != null)

{

dbGame.Name = game.Name;

dbGame.Description = game.Description;

dbGame.Price = game.Price;

dbGame.Category = game.Category;

}

}

context.SaveChanges();

}
public void DeleteGame(Game game)

{

IEnumerable orders = context.Orders

.Include(o => o.OrderLines.Select(ol => ol.Game))

.Where(o => o.OrderLines

.Count(ol => ol.Game.GameId == game.GameId) > 0)

.ToArray();

foreach (Order order in orders)

{

context.Orders.Remove(order);

}

context.Games.Remove(game);

context.SaveChanges();

}
public void SaveOrder(Order order)

{

// ...

}

}

}

Game ni o'chirish ma'lumotlar bazasidan ushbu Game ni o'z ichiga olgan barcha Order ni o'chirib tashlaydi. Biz shunchaki Game ni o'chira olmaymiz, chunki bu ma'lumotlar bazasi serverida aniqlik xatoligini keltirib chiqaradi. DeleteGame () usulidagi murakkab LINQ so'rovi ma'lumotlar bazasining yaxlitligini saqlab, o'chirilgan Game ga bog'liq bo'lgan qatorlarni Order and OrderLines jadvallaridan olib tashlaydi.

Ma'lumotlar bazasida mos keladigan qatorlar bo'lmagan Game moslamalari GameID xususiyatining nol qiymatlari bilan aniqlanadi. Agar Game ob'ekti GameID xususiyatida nolga teng qiymatga ega bo'lsa, ma'lumotlar bazasidagi mavjud qator yangilanadi.