Entity Framework - Eager loading, all properties to list - entity-framework

Question

I have a simple project in which i have the following model.
Customer 1--->N Addresses N<----1 City N<----1 Country
^
N|
|
AddressTypes 1-------+
Here is my code:
public partial class Customer {
public Customer() {
this.Address = new HashSet<Address>();
}
public int Id {get;set;}
public string FirstName {get;set;}
public string LastName {get;set;}
public System.DateTime Birthday {get;set;}
public virtual ICollection<Address> Address {get;set;}
}
public partial class Address {
public int Id {get;set;}
public string Street {get;set;}
public string Area {get;set;}
public string Post {get;set;}
public bool isDeleted {get;set;}
public virtual Customer Customer {get;set;}
public virtual City City {get;set;}
public virtual AddressType AddressType {get;set;}
}
public partial class AddressType {
public AddressType() {
this.Address = new HashSet<Address>();
}
public int Id {get;set;}
public string Name {get;set;}
public virtual ICollection<Address> Address {get;set;}
}
public partial class Country {
public Country() {
this.City = new HashSet<City>();
}
public int Id {get;set;}
public string Name {get;set;}
public virtual ICollection<City> City {get;set;}
}
public partial class City {
public City() {
this.Address = new HashSet<Address>();
}
public int Id {get;set;}
public string Name {get;set;}
public virtual ICollection<Address> Address {get;set;}
public virtual Country Country {get;set;}
}
public partial class MyModelContext : DbContext {
public MyModelContext()
: base("name=MyModelContext") {
this.Configuration.LazyLoadingEnabled = true;
this.Configuration.ProxyCreationEnabled = false;
}
public virtual DbSet<Country> Countries {get;set;}
public virtual DbSet<City> Cities {get;set;}
public virtual DbSet<AddressType> AddressTypes {get;set;}
public virtual DbSet<Address> Addresses {get;set;}
public virtual DbSet<Customer> Customers {get;set;}
}
I want to return a list of customers. At first i tried to do a simple Customers.ToList() but i was getting an exception during serialization and i read that this was caused by cyclical references. So i added
Configuration.LazyLoadingEnabled = true;
Configuration.ProxyCreationEnabled = false;
and then i was able to get the customers but without the addresses. I tried doing:
public List<Customer> getCustomers() {
MyModelContext db = new MyModelContext();
return db.Customers.Include("Address").ToList();
}
but i don't know how to retrieve ALL the properties. I want to get in the list every customer and his addresses including the city, country, addresstype of each address. How can i do it?

Answer 1

You have couple of options:
1. Use DTOs (Data Transfer Objects).
2. Explicitly ignore the problematic property that contains the circular references to the parent object by applying the below Attributes:
// in Address entity
[IgnoreDataMember]
[XmlIgnore]
[NonSerialized]
public Customer Custom { get; set; }
Also in AddressType.Address, City.Address, and Country.City.
3. Project your entities into anonymous objects and exclude the pr:
db.Customers.Select(c => new
{
c.Id,
c.FirstName,
c.LastName,
c.Birthday,
Address = c.Address.Select<Address, object>(a => new
{
a.Id,
AddressType = new
{
a.AddressType.Id,
a.AddressType.Name
},
a.Area,
City = new
{
a.City.Id,
Country = new
{
a.City.Country.Id,
a.City.Country.Name
},
a.City.Name,
},
a.Post,
a.Street,
a.isDeleted
}),
});
You'll have to turn LazyLoadingEnabled and ProxyCreationEnabled back on in order for it to work (or use Include).
(As a side note, i don't really understand why you need this circular references at all, what benefit do you get from AddressType.Address?)

Answer 2

I solved it this way:
public List<Customer> getCustomers() {
var customers = db.CustomerSet.Include("Address")
.Include("Address.AddressType")
.Include("Address.City")
.Include("Address.City.Country")
.ToList();
return customers;
}
i don't really like that i have to explicitly write all the properties of the customer and there is not a generic way of doing what i want but it works.