EF Context not keeping values after adding entity - entity-framework

Question

Edit Is this post lacking sufficient information to get some guidance?
I have this method to insert an entity into the database:
public void Insert(T entity)
{
_context.Set<T>().Add(entity);
_context.SaveChanges();
}
When I inspect entity before adding it to the context, my CustomerRole field is there. Once the add has taken place, the context doesn't seem to have it. Because of this, I am receiving this error:
Entities in 'CcDataContext.Customers' participate in the
'Customer_CustomerRole' relationship. 0 related
'Customer_CustomerRole_Target' were found. 1
'Customer_CustomerRole_Target' is expected.
These images show what I mean:
Inspecting my entity
Inspecting the context
Can anyone explain this behaviour and what I can do about it?
This is the structure of my classes (cut down for brevity):
public class Customer : BaseEntity
{
public CustomerRole CustomerRole { get; set; }
}
class CustomerMap : EntityTypeConfiguration<Customer>
{
public CustomerMap()
{
HasRequired(t => t.CustomerRole)
.WithMany(t => t.Customers);
}
}
public class CustomerRole : BaseEntity
{
private ICollection<Customer> _customers;
public ICollection<Customer> Customers
{
get { return _customers ?? (new List<Customer>()); }
set { _customers = value; }
}
}
I can confirm that customer map is being added to the configuration and my database is built in line with them.
This is the call I am making which does the insert:
public Customer InsertGuestCustomer()
{
var customer = new Customer();
CustomerRole guestRole = GetCustomerRoleByName("Guest");
if (guestRole == null)
throw new Exception("Customer Role is not defined!");
customer.UserName = "";
customer.EmailAddress = "";
customer.Password = "";
customer.IsAdmin = false;
customer.CustomerRole = guestRole;
_customerRepository.Insert(customer);
return customer;
}
I have no other data in my database, this would be the first customer record and only one CustomerRole. My Customer table has a Foreign Key pointing to my CustomerRole.Id table / column.

Answer 1

Mark your navigation properties as virtual and initialize the collection property in the entity constructor rather than from the property getter.
public class Customer : BaseEntity
{
public virtual CustomerRole CustomerRole { get; set; }
}
...
public class CustomerRole : BaseEntity
{
public CustomerRole()
{
Customers = new List<Customer>();
}
public virtual ICollection<Customer> Customers { get; protected set; }
}
In your Customers property, you were returning a new List in the getter when the backing field was null, but you never assigned this to your backing field.