How to get newly generated id on the MVC model - asp.net-mvc

Question

I have the model that has multiple entities. For example I have an order that have CustomerId to foreign key. In the model I have some fields from the order and some fields from the customer entity. When I am saving new record I would like to save customer first, get newly generated identity value and put it to the order table. How to achieve that? I can do that by getting MAX(ID) from the customer table, however I am pretty sure that there is better way to handle that.
This is my controller method:
public ActionResult Create(OrderModels model, FormCollection form)
{
try
{
Customer customer = new Customer() { FirstName = model.FirstName, MiddleName = model.MiddleName, SecondName = model.SecondName, Email = model.Email, PhoneNbr = model.PhoneNbr };
int orderSource = Int32.Parse(form["OrderSourceList"]);
int paymentType = Int32.Parse(form["PaymentTypeList"]);
string warehouseGuid = form["Warehouses"];
ProductLogic productLogic = new ProductLogic();
Product product = productLogic.GetProductByArticle(model.Article);
DateTime now = DateTime.Now;
SalesOrder salesOrder = new SalesOrder()
{
OrderNbr = model.OrderNbr,
OrderSourceId = orderSource,
NpWarehouseRef = new Guid(warehouseGuid),
TTN = model.TTN,
OrderStatusId = 1,
PaymentTypeId = paymentType,
OrderDate = DateTime.Now
};
using (AccountingRepository repository = new AccountingRepository())
{
repository.AddOrUpdate<Customer>(customer);
repository.AddOrUpdate<SalesOrder>(salesOrder);
}
return RedirectToAction("Index");
}
catch (Exception e)
{
return View();
}
}
AccountingRepository has dispose method
public void Dispose()
{
if (_context != null)
{
_context.SaveChanges();
_context.Dispose();
}
}
My Order class:
using System;
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.ModelConfiguration;
namespace Accounting.Entity
{
[Table("SalesOrder", Schema = "dbo")]
public class SalesOrder
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int? Id { get; set; }
...
public int? CustomerId { get; set; }
...
public virtual Customer Customer { get; set; }
internal class Config : EntityTypeConfiguration<SalesOrder>
{
public Config()
{
HasRequired(r => r.Customer)
.WithMany(r => r.SalesOrder)
.HasForeignKey(r => r.CustomerId);
}
}
}
}
My Customer class:
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.ModelConfiguration;
namespace Accounting.Entity
{
[Table("Customer", Schema = "dbo")]
public class Customer
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int? Id { get; set; }
public string FirstName { get; set; }
public string MiddleName { get; set; }
public string SecondName { get; set; }
public string PhoneNbr { get; set; }
public string Email { get; set; }
public virtual HashSet<SalesOrder> SalesOrder { get; set; }
internal class Config : EntityTypeConfiguration<Customer>
{
public Config()
{
}
}
}
}

Answer 1

Two ways:
Save the customer entity, and Entity Framework will back fill the PK property with it's ID. You can then use this for the order entity.
db.Customers.Add(customer);
db.SaveChanges();
order.CustomerId = customer.Id; // has a value now
Just associate the customer with the order via a navigation property. When you save everything Entity Framework works out which relationships need to be saved first and then fills in the appropriate FK ids in the related entities.
order.Customer = customer;
db.Orders.Add(order);
db.SaveChanges(); // customer is saved first and the id is set for order.CustomerId automatically