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我正在使用實體框架6.當我更新導航屬性到一個對象，然後執行SaveChanges（），而不是引用現有的對象時，它會在引用表中創建一個副本。實體框架 - 斷開連接的上下文和重複記錄
我舉幾個例子如下：
以下示例按預期工作。它創建了一個「客戶」和「訂單」，併成功他們相關聯：
Homer Simpson is buying Duff beer
ConsoleApplication1.Objects.Customer - Added
ConsoleApplication1.Objects.Order - Added
然而，
// Homer Simpson buys some Duff beer
Console.WriteLine("Homer Simpson is buying Duff beer");
Customer customer = new Customer
{
Name = "Homer Simpson"
};
Order order1 = new Order
{
Description = "Duff Beer"
};
customer.Orders.Add(order1);
using (EFContext db = new EFContext())
{
db.Customers.Add(customer);
DisplayChanges(db);
db.SaveChanges();
}
輸出，如果我嘗試再添加一個命令和我現有的客戶聯繫起來，當保存我的改變它複製DB中的客戶對象以及我創造了現有秩序：
// Homer Simpson buys some Duff beer
Console.WriteLine("Homer Simpson is buying Duff beer");
Customer customer = new Customer
{
Name = "Homer Simpson"
};
Order order1 = new Order
{
Description = "Duff Beer"
};
customer.Orders.Add(order1);
using (EFContext db = new EFContext())
{
db.Customers.Add(customer);
DisplayChanges(db);
db.SaveChanges();
}
// Homer Simpson buys some Buzz Cola
Console.WriteLine("\r\nHomer Simpson is buying Buzz Cola");
Order order2 = new Order
{
Description = "Buzz Cola",
Customer = customer
};
using (EFContext db = new EFContext())
{
db.Orders.Add(order2);
DisplayChanges(db);
db.SaveChanges();
}
輸出
Homer Simpson is buying Duff beer
ConsoleApplication1.Objects.Customer - Added
ConsoleApplication1.Objects.Order - Added
Homer Simpson is buying Buzz Cola
ConsoleApplication1.Objects.Order - Added
ConsoleApplication1.Objects.Customer - Added
ConsoleApplication1.Objects.Order - Added
如果我設置爲相對於導航屬性的外鍵，記錄不重複。然而，在這種情況下，我沒有獲得相關對象的屬性，直到我明確地加載：
// Homer Simpson buys some Duff beer
Console.WriteLine("Homer Simpson is buying Duff beer");
Customer customer = new Customer
{
Name = "Homer Simpson"
};
Order order1 = new Order
{
Description = "Duff Beer"
};
customer.Orders.Add(order1);
using (EFContext db = new EFContext())
{
db.Customers.Add(customer);
DisplayChanges(db);
db.SaveChanges();
}
// Homer Simpson buys some donuts
Console.WriteLine("\r\nHomer Simpson is buying donuts");
Order order3 = new Order
{
Description = "Donuts",
CustomerID = 1
};
if (order3.Customer == null)
{
Console.WriteLine("Customer is null before save!");
}
else
{
Console.WriteLine("The customer is " + customer.Name + " before save!");
}
using (EFContext db = new EFContext())
{
db.Orders.Add(order3);
DisplayChanges(db);
db.SaveChanges();
}
if (order3.Customer == null)
{
Console.WriteLine("Customer is null after save!");
}
else
{
Console.WriteLine("The customer is " + customer.Name + " after save!");
}
using (EFContext db = new EFContext())
{
db.Orders.Attach(order3);
db.Entry(order3).Reference(x => x.Customer).Load();
}
if (order3.Customer == null)
{
Console.WriteLine("Customer is null after forced load!");
}
else
{
Console.WriteLine("The customer is " + customer.Name + " after forced load!");
}
輸出
Homer Simpson is buying Duff beer
ConsoleApplication1.Objects.Customer - Added
ConsoleApplication1.Objects.Order - Added
Homer Simpson is buying donuts
Customer is null before save!
ConsoleApplication1.Objects.Order - Added
Customer is null after save!
The customer is Homer Simpson after forced load!
是任何人都能夠提供什麼建議嗎？我明白你可以手動連接和分離實體，但據說，我正在處理一些相當複雜的對象。我想找到一個簡單的方法來控制實體框架中的變更跟蹤。
問候
彼得·迪根
沒有簡單的方法 - 使用斷開的對象圖從未在EF中簡單/簡單。你可以嘗試[GraphDiff]（https://github.com/refactorthis/GraphDiff）包，試圖解決這個問題。不幸的是，作者不再支持它。 –