Using Entity Framework 4.0 with Code-First and POCO: How to Get Parent Object with All its Children
- by SirEel
I'm new to EF 4.0, so maybe this is an easy question. I've got VS2010 RC and the latest EF CTP. I'm trying to implement the "Foreign Keys" code-first example on the EF Team's Design Blog, http://blogs.msdn.com/efdesign/archive/2009/10/12/code-only-further-enhancements.aspx.
public class Customer
{
public int Id { get; set;
public string CustomerDescription { get; set;
public IList<PurchaseOrder> PurchaseOrders { get; set; }
}
public class PurchaseOrder
{
public int Id { get; set; }
public int CustomerId { get; set; }
public Customer Customer { get; set; }
public DateTime DateReceived { get; set; }
}
public class MyContext : ObjectContext
{
public RepositoryContext(EntityConnection connection) : base(connection){}
public IObjectSet<Customer> Customers { get {return base.CreateObjectSet<Customer>();} }
}
I use a ContextBuilder to configure MyContext:
{
var builder = new ContextBuilder<MyContext>();
var customerConfig = _builder.Entity<Customer>();
customerConfig.Property(c => c.Id).IsIdentity();
var poConfig = _builder.Entity<PurchaseOrder>();
poConfig.Property(po => po.Id).IsIdentity();
poConfig.Relationship(po => po.Customer)
.FromProperty(c => c.PurchaseOrders)
.HasConstraint((po, c) => po.CustomerId == c.Id);
...
}
This works correctly when I'm adding new Customers, but not when I try to retrieve existing Customers. This code successfully saves a new Customer and all its child PurchaseOrders:
using (var context = builder.Create(connection))
{
context.Customers.AddObject(customer);
context.SaveChanges();
}
But this code only retrieves Customer objects; their PurchaseOrders lists are always empty.
using (var context = _builder.Create(_conn))
{
var customers = context.Customers.ToList();
}
What else do I need to do to the ContextBuilder to make MyContext always retrieve all the PurchaseOrders with each Customer?
