Entity Framework with POCO and FK pattern in the model - null reference exception

Question

I am using Entity Framework 4 with a POCO code generation template from Microsoft downloaded from Visual Studio Gallery. I also leave the default option "Include foreign keys in the model", selected when generating the EF-model from the database.

I was able to reproduce this problem with a very simple model, only two tables / classes in an optional one-to-many relationship. In this case, I use the address and identity. A person can have one or zero address, and the address can have zero for many people.

The tables look like this:

CREATE TABLE [dbo].[Person](
    [PersonID] [uniqueidentifier] NOT NULL,
    [FirstName] [nvarchar](50) NULL,
    [LastName] [nvarchar](50) NULL,
    [AddressID] [uniqueidentifier] NULL,
 CONSTRAINT [PK_Person] PRIMARY KEY CLUSTERED ([PersonID] ASC )

 CREATE TABLE [dbo].[Address](
    [AddressID] [uniqueidentifier] NOT NULL,
    [Street1] [nvarchar](50) NOT NULL,
    [Street2] [nvarchar](50) NULL,
    [City] [nvarchar](50) NOT NULL,
    [State] [char](2) NOT NULL,
    [Country] [nvarchar](50) NOT NULL,
 CONSTRAINT [PK_Address] PRIMARY KEY CLUSTERED ([AddressID] ASC)

ALTER TABLE [dbo].[Person]  WITH CHECK ADD  CONSTRAINT [FK_Person_Address] 
FOREIGN KEY([AddressID])
REFERENCES [dbo].[Address] ([AddressID])

When I try to create an Address object and add it to an existing object, the Person pulled from the database, I get a null reference exception:

TestPOCOEntities ctx = new TestPOCOEntities();

var person = ctx.People.FirstOrDefault(p => p.PersonID == new Guid("58AD37B4-1EBE-4649-940C-A141732C9901"));

var addr = new Address {AddressID = Guid.NewGuid(), Street1 = "123 Main St"};
person.Address = addr; // This line throws the exception

ctx.SaveChanges();

, , Person AddressID. ( , System.Data.Objects.EntityEntry.FixupEntityReferenceByForeignKey(EntityReference reference).)

, EF POCO. , POCO, " " .

, :

var addr = new Address {AddressID = Guid.NewGuid(), Street1 = "123 Main St"};
ctx.Addresses.AddObject(addr); // Adding this line...
person.Address = addr; // Means no more exception here!

, POCO . ? - ? - ?

Answer 1

EF, (resave changes with new data):

http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/832af255-d1c2-41d5-9e95-9cdf3b15bb57

-, savechanges !