How is the method to include() in Repository?

[nishika]

In the construction of the application, use the patent Repository. Repository interface:

public interface IShopContext
{
    IQueryable<T> GetAllIncluding<T>(params Expression<Func<T, object>>[] include) where T : class;
}

Implementation of the interface in the context of EF:

public class ShopContext : DbContext, IShopContext
{
    public ShopContext()
        : base("name=ShopDB")
    {
    }
public virtual DbSet<Customer>    Customers { get; set; }
public virtual DbSet<Order>      Orders { get; set; }

public IQueryable<T> GetAllIncluding<T>(params Expression<Func<T, object>>[] include) where T : class
{
    var retVal = this.Set<T>();

    foreach(var item in include)
    {
        retVal.Include(item);
    }

    return retVal;

}

}

Use the CodeFirst approach. The base is generated. In SQL SMS 2014, the link between Customers-Orders : One-to-Many and visible on diagram. The table is available.

Классы сущностей:

public class Customer

{

public int CustomerId { get; set; }

public string FirstName { get; set; }

public string LastName { get; set; }

public string Patronymic { get; set; }
public ICollection<Order> Orders { get; set; }

public Customer()
{
    Orders = new List<Order>();
}

}
public class Order

{

public int OrderId { get; set; }

public string Number { get; set; }

public int CustomerId { get; set; }

public Customer Customer { get; set; }

}

Test code

[TestInitialize]

void Initialize()

{

con = new ShopContext();

}

[TestMethod]

public void Query_GetCustomersListIncluding_NoExc()

{

Initialize();
var l = con.GetAllIncluding<Customer>(c => c.Orders).ToList();

foreach (var item in l)
{
    Trace.TraceInformation($"{item.LastName}");
    foreach (var i in item.Orders)
    {
        Trace.TraceInformation($"{i.Number}");
    }                
}

}

The problem is, this test only gives out the name of the customers, but doesn't take orders. At the debage, it was discovered that the variables should contain a link to the object with the collection of orders, empty. What's the problem?

[Laycee]

The mistake is:

retVal.Include(item);

Must be:

retVal = retVal.Include(item);