‫آشنایی با الگوی مخزن نشتی‌دار در برنامه‌نویسی #C و روش‌های رفع آن

public interface IProductRepository
{
    IQueryable<Product> GetProducts();
}

public class ProductRepository : IProductRepository
{
    private readonly DbContext _context;
    
    public ProductRepository(DbContext context)
    {
        _context = context;
    }
    
    public IQueryable<Product> GetProducts()
    {
        return _context.Products;
    }
}

var discountedProducts = repository.GetProducts()
    .Where(p => p.Category == "EBooks")
    .Where(p => p.Price > 100)
    .OrderBy(p => p.Name)
    .Skip(100)
    .Take(10)
    .ToList();

public interface IRepository<T> where T : class
{
    DbSet<T> Entities { get; }
    void Attach(T entity);
    void DetachEntity(T entity);
    EntityEntry<T> GetEntityEntry(T entity);
}

public Customer GetById(int id)
{
    try
    {
        return _context.Customers.Find(id);
    }
    catch (SqlException ex)
    {
        throw;
    }
}

public class OrderRepository : IOrderRepository
{
    private readonly DbContext _context;
    
    public Order GetById(int id)
    {
        return _context.Orders.Find(id);
    }
}

var order = orderRepository.GetById(1111);
foreach (var item in order.OrderItems)
{
    // ممکن است کوئری‌های اضافی اجرا شود
}

public interface IProductRepository
{
    IReadOnlyCollection<Product> GetProductsByCategory(string category);
    IReadOnlyCollection<Product> GetDiscountedProducts(decimal minPrice);
    PagedResult<Product> GetProductsPaged(int page, int pageSize, string sortField);
}

public interface ISpecification<T>
{
    Expression<Func<T, bool>> Criteria { get; }
    List<Expression<Func<T, object>>> Includes { get; }
    Expression<Func<T, object>> OrderBy { get; }
    int Take { get; }
    int Skip { get; }
}

public interface IRepository<T>
{
    IReadOnlyList<T> FindAll(ISpecification<T> spec);
}

public class DiscountedEbooksSpecification : BaseSpecification<Product>
{
    public DiscountedEbooksSpecification(decimal minPrice)
        : base(p => p.Category == "Ebooks" && p.Price > minPrice)
    {
        AddOrderBy(p => p.Name);
        ApplyPaging(10, 10);
    }
}

var spec = new DiscountedEbooksSpecification(69);
var products = repository.FindAll(spec);

public class EntityNotFoundException : Exception
{
    public EntityNotFoundException(string entityType, object key)
        : base($"{entityType} با شناسه {key} یافت نشد.")
    {
    }
}

public Customer GetById(int id)
{
    try
    {
        var customer = _context.Customers.Find(id);
        if (customer == null)
            throw new EntityNotFoundException("Customer", id);
        return customer;
    }
    catch (SqlException ex)
    {
        throw new Exception("خطا در دسترسی به داده‌ها", ex);
    }
}

public Order GetOrderWithDetails(int id)
{
    return _context.Orders
        .Include(o => o.OrderItems)
        .ThenInclude(i => i.Product)
        .FirstOrDefault(o => o.Id == id);
}

public OrderDetailsDto GetOrderDetails(int id)
{
    return _context.Orders
        .Where(o => o.Id == id)
        .Select(o => new OrderDetailsDto
        {
            OrderId = o.Id,
            CustomerName = o.Customer.Name,
            Items = o.OrderItems.Select(i => new OrderItemDto
            {
                ProductName = i.Product.Name,
                Quantity = i.Quantity
            }).ToList()
        })
        .FirstOrDefault();
}