LINQ到實體插入多個子女的關係記錄爲許多一對多關係使用POCO

Question

我有類似下面的一個數據庫：

Order 
=============== 
OrderID 
Description 
EmployeeID 
...other fields 


Product 
=============== 
ProductID 
...other fields 


OrderProducts 
=============== 
OrderID 
ProductID 


Employee 
=============== 
EmployeeID 
...other fields 

我使用LINQ到實體和EDMX文件已經創建而沒有OrderProducts表，因爲它只是一個連接表。產品表是靜態產品的列表 - 我目前不需要插入任何行。 Order表我可以插入行成功地使用下面的代碼：

[Serializable] 
public class MyOrderObject 
{ 
    public int OrderID { get; set; } 
    public string OrderDescription { get; set; } 
    public int? EmployeeID { get; set; } 
    public IEnumerable<MyProductObject> ProductsList { get; set; } 
    ...other fields 
} 

[Serializable] 
public class MyProductObject 
{ 
    public int ProductID { get; set; } 
    ...other fields 
} 


private static void AddNewOrder(MyOrderObject order) 
{ 
    using (var context = DatabaseHelper.CreateContext()) 
    { 
     var dbOrder = new Order 
     { 
     OrderID = order.OrderID, 
     Description = order.OrderDescription, 
     Employee = context.Employees.SingleOrDefault(x => x.EmployeeID == order.EmployeeID), 
     } 
     context.AddToOrders(dbOrder); 
     context.SaveChanges(); 
    } 
} 

如何插入到數據庫中我的孩​​子的關係記錄列表？ 我已經試過：

List<int> ProductIDs = order.ProductsList.Select(x => x.ProductID).ToList(); 
//dbOrder.Products.Attach(context.Products.Where(x => ProductIDs.Contains(x.ProductID))); 
//or dbOrder.Products = context.Products.Where(x => ProductIDs.Contains(x.ProductID)); 
//or dbOrder.Products = context.Products.Contains(ProductIDs); 
//or foreach(var p in order.ProductsList) 
// { 
//  context.AttachTo("Products", new Product { ProductID = p.ProductID }); 
// } 

Answer 1

無需更改對象類型：我還沒有被使用EF4

var dbOrder = new Order 
{ 
    OrderID = order.OrderID, 
    Description = order.OrderDescription, 
    Employee = context.Employees.SingleOrDefault(x => x.EmployeeID == order.EmployeeID), 
} 

//this adds the relationship to the child without adding a new child record - perfect! 
foreach(var p in order.ProductsList) 
{ 
    dbOrder.Products.Add(p); 
} 

context.AddToOrders(dbOrder); 
context.SaveChanges(); 

Answer 2

您需要將ProductsList類型更改爲ICollection。並確保它是EDMX映射模型的一部分。

public class MyOrderObject 
{ 
    public int OrderID { get; set; } 
    public string OrderDescription { get; set; } 
    public int? EmployeeID { get; set; } 
    public ICollection<MyProductObject> ProductsList { get; set; } 
    ...other fields 
} 

然後你就可以將產品添加

var products = context.Products.Where(/**/); 
foreach(var p in products) 
    order.ProductsList.Add(p);