Entity Framework identity column always zero - entity-framework

Question

I'm using following class to insert products to database.
ID column is primary key.
After adding multiple products to db context (without calling savechanges method) all newly added rows identity columns are zero!
My scene...
User adds several products and browse them on the data grid.
User selects one product and adds some barcodes to selected product.
When user finishes the job clicks on save button and application calls SaveChanges method!
When user wants to add some barcodes to products firstly I need to find selected product from context and adds entered barcode text to Barcodes list. But I cant do that because all products identity columns value are the same and they are zero.
How can I solve this problem?
public class Product
{
public int ProductID { get; set; }
public string Code { get; set; }
public string Name { get; set; }
public virtual List<Barcode> Barcodes { get; set; }
}
public class Barcode
{
public int BarcodeID { get; set; }
public string BarcodeText { get; set; }
public int ProductID { get; set; }
public virtual Product Product { get; set; }
}

Answer 1

Identity column value is assigned by database when you are inserting record into table. Before you call SaveChanges no queries are executed, nothing is passed to database and back. Context just keeps in-memory collection of entities with appropriate state (state defines which time of query should be executed during changes saving - for new entities, which have Added state, insert query should be generated and executed). So, ID stays with its default value, which is zero for integer. You should not give value manually. After inserting entities into database, context will receive ID value and update entity.
UPDATE: When you are adding Barcode to existing product, then EF is smart enough to update keys and foreign keys of entities:
var product = db.Products.First(); // some product from database
var barcode = new Barcode { BarcodeText = "000" };
// at this point barcode.ID and barcode.ProductID are zeros
product.Barcodes.Add(barcode);
db.SaveChanges(); // execute insert query
// at this point both PK and FK properties will be updated by EF