방법: POCO 엔터티의 변경 내용 검색

이 항목에서는 변경 내용 추적 프록시를 사용하여 POCO 엔터티의 변경 내용을 추적하는 방법에 대해 설명합니다. 또한 DetectChanges 메서드를 호출하여 프록시 없이 변경 내용을 검색하는 방법도 보여 줍니다. 기본적으로 SaveChanges 메서드는 먼저 DetectChanges 메서드를 호출합니다. 자세한 내용은 POCO 엔터티에서 변경 내용 추적(Entity Framework)을 참조하십시오.

이 항목의 예제에서는 방법: POCO 엔터티 정의(Entity Framework)에서 정의한 POCO 클래스와 방법: 사용자 지정 개체를 사용할 수 있도록 모델링 및 매핑 파일 사용자 지정(Entity Framework)에서 정의한 AdventureWorks 기반 데이터 모델을 사용합니다.

예제

이 예제에서는 Entity Framework 에서 POCO 엔터티의 변경 내용을 추적할 수 있도록 하는 POCO 자동 추적 프록시를 추가합니다.

' Specify the order to update. 
Dim orderId As Integer = 43680

Using context As New POCOAdventureWorksEntities()
    Try
        ' Enable lazy loading. 
        context.ContextOptions.LazyLoadingEnabled = True

        Dim order As Order = context.Orders.Where(Function(o) o.SalesOrderID = orderId).First()
        ' Create a new item and add it to the order. 
        ' The Entity Framework is going to generate 
        ' proxy object for the newItem object. 
        Dim newItem As LineItem = context.CreateObject(Of LineItem)()
        newItem.SalesOrderDetailID = 0
        ' Assign the order to the new LineItem. 
        newItem.SalesOrderID = orderId
        newItem.OrderQty = 1
        newItem.ProductID = 750
        newItem.UnitPriceDiscount = 0
        newItem.UnitPrice = 2171.2942D
        newItem.ModifiedDate = DateTime.Today
        newItem.rowguid = Guid.NewGuid()
        newItem.SpecialOfferID = 1


        ' Add the new item to the order. 
        ' The order will be added to the context because 
        ' we are working with POCO proxies. 
        order.LineItems.Add(newItem)

        ' The state of the newItem is Added. 
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State.ToString())

        ' Change the status and ship date of an existing order. 
        order.ShipDate = DateTime.Today

        ' The sate of the order item is Modified. 
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(order).State.ToString())

        ' The newItem is set to Unchanged.
        context.SaveChanges()

        ' Change the newly added item. 
        newItem.OrderQty = 2

        ' The changes are tracked as they occur and the state of the object is Modified. 
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State.ToString())

        ' Delete the newly created object. 
        context.DeleteObject(newItem)

        ' Save changes in the object context to the database 
        ' after first detecting changes again. 
        context.SaveChanges()
    Catch ex As UpdateException
        Console.WriteLine(ex.ToString())
    Catch ex As InvalidOperationException
        Console.WriteLine(ex.ToString())
    End Try
End Using

// Specify the order to update.
int orderId = 43680;

using (POCOAdventureWorksEntities context =
        new POCOAdventureWorksEntities())
{
    try
    {
        // Enable lazy loading.
        context.ContextOptions.LazyLoadingEnabled = true;

        Order order = context.Orders.
                          Where(o => o.SalesOrderID == orderId).First();
        // Create a new item and add it to the order.
        // The Entity Framework is going to generate 
        // proxy object for the newItem object. 
        LineItem newItem = context.CreateObject<LineItem>();
        newItem.SalesOrderDetailID = 0;
        // Assign the order to the new LineItem. 
        newItem.SalesOrderID = orderId;
        newItem.OrderQty = 1;
        newItem.ProductID = 750;
        newItem.UnitPriceDiscount = 0;
        newItem.UnitPrice = 2171.2942M;
        newItem.ModifiedDate = DateTime.Today;
        newItem.rowguid = Guid.NewGuid();
        newItem.SpecialOfferID = 1;

        // Add the new item to the order.
        // The order will be added to the context because 
        // we are working with POCO proxies.
        order.LineItems.Add(newItem);

        // The state of the newItem is Added.
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State);

        // Change the status and ship date of an existing order.
        order.ShipDate = DateTime.Today;

        // The sate of the order item is Modified.
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(order).State);

        // The newItem is set to Unchanged.
        context.SaveChanges();

        // Change the newly added item.
        newItem.OrderQty = 2;

        // The changes are tracked as they occur and the state of the object is Modified.
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State);

        // Delete the newly created object.
        context.DeleteObject(newItem);

        // Save changes in the object context to the database 
        // after first detecting changes again.
        context.SaveChanges();
    }
    catch (UpdateException ex)
    {
        Console.WriteLine(ex.ToString());
    }
    catch (InvalidOperationException ex)
    {
        Console.WriteLine(ex.ToString());
    }
}

이 예제에서는 ObjectContext에 의해 추적되지 않는 POCO 엔터티를 추가합니다. DetectChanges 메서드는 ObjectStateManager를 개체의 현재 상태와 동기화하기 위해 호출됩니다.

' Specify the order to update. 
Dim orderId As Integer = 43680
Using context As New POCOAdventureWorksEntities()
    Try
        ' Disable proxy object creation. 
        context.ContextOptions.ProxyCreationEnabled = False

        Dim order As Order = context.Orders.Include("LineItems").Where(Function(o) o.SalesOrderID = orderId).First()


        ' Create a new item and add it to the order. 
        ' The Entity Framework is not going to generate 
        ' a proxy object for the newItem object. 
        Dim newItem As New LineItem()
        newItem.SalesOrderDetailID = 0
        ' Assign the order to the new LineItem. 
        newItem.SalesOrderID = orderId
        newItem.OrderQty = 1
        newItem.ProductID = 750
        newItem.UnitPriceDiscount = 0
        newItem.UnitPrice = 2171.2942D
        newItem.ModifiedDate = DateTime.Today
        newItem.rowguid = Guid.NewGuid()
        newItem.SpecialOfferID = 1

        ' Add the new item to the order. 
        ' The order will not be added to the context because 
        ' we are working with pure POCO objects. 
        order.LineItems.Add(newItem)

        Dim entry As ObjectStateEntry = Nothing
        ' There is no entry for the object because it is not in the context. 
        context.ObjectStateManager.TryGetObjectStateEntry(newItem, entry)
        Console.WriteLine("{0}", If(entry IsNot Nothing, entry.State.ToString(),
                                    "There is no entry for this object"))

        ' Call DetectChanges to synchronize the objects with the state manager. 
        context.DetectChanges()

        ' Try getting the entry after Detectchagnes was called. 
        context.ObjectStateManager.TryGetObjectStateEntry(newItem, entry)
        Console.WriteLine("{0}", If(entry IsNot Nothing, entry.State.ToString(),
                                    "There is no entry for this object"))

        ' Change the status and ship date of an existing order. 
        order.ShipDate = DateTime.Today

        ' Even though we changed the ShipDate of the item in the context 
        ' the status of the order is still Unchanged. 
        ' The changes to the POCO entity without the chane tracking proxy 
        ' are not tracked as they occur. 
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(order).State.ToString())

        ' Calls DetectChanges(). The newItem is set to Unchanged.
        context.SaveChanges()

        ' Change the newly added item. 
        newItem.OrderQty = 2

        ' The state of the newItem is Unchanged. 
        ' If the newItem was a POCO proxy entity the changes would be tracked as they occur 
        ' and the state would be Modified. 
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State.ToString())

        ' Call DetectChanges to synchronize the objects with the state manager. 
        context.DetectChanges()

        ' The state of the newItem is now Modified. 
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State.ToString())

        ' Delete the newly created object. 
        context.DeleteObject(newItem)

        ' Save changes in the object context to the database 
        ' after first detecting changes again. 
        context.SaveChanges()
    Catch ex As UpdateException
        Console.WriteLine(ex.ToString())
    Catch ex As InvalidOperationException
        Console.WriteLine(ex.ToString())
    End Try
End Using

// Specify the order to update.
int orderId = 43680;
using (POCOAdventureWorksEntities context =
        new POCOAdventureWorksEntities())
{
    try
    {
        // Disable proxy object creation. 
        context.ContextOptions.ProxyCreationEnabled = false;

        Order order = context.Orders.Include("LineItems").
                          Where(o => o.SalesOrderID == orderId).First();


        // Create a new item and add it to the order.
        // The Entity Framework is not going to generate 
        // a proxy object for the newItem object. 
        LineItem newItem = new LineItem();
        newItem.SalesOrderDetailID = 0;
        // Assign the order to the new LineItem. 
        newItem.SalesOrderID = orderId;
        newItem.OrderQty = 1;
        newItem.ProductID = 750;
        newItem.UnitPriceDiscount = 0;
        newItem.UnitPrice = 2171.2942M;
        newItem.ModifiedDate = DateTime.Today;
        newItem.rowguid = Guid.NewGuid();
        newItem.SpecialOfferID = 1;

        // Add the new item to the order.
        // The order will not be added to the context because
        // we are working with pure POCO objects.
        order.LineItems.Add(newItem);

        ObjectStateEntry entry = null;
        // There is no entry for the object because it is not in the context.
        context.ObjectStateManager.TryGetObjectStateEntry(newItem, out entry);
        Console.WriteLine("{0}", entry!=null ? entry.State.ToString() : "There is no entry for this object");

        // Call DetectChanges to synchronize the objects with the state manager.
        context.DetectChanges();

        // Try getting the entry after Detectchagnes was called.
        context.ObjectStateManager.TryGetObjectStateEntry(newItem, out entry);
        Console.WriteLine("{0}", entry != null ? entry.State.ToString() : "There is no entry for this object");

        // Change the status and ship date of an existing order.
        order.ShipDate = DateTime.Today;

        // Even though we changed the ShipDate of the item in the context 
        // the status of the order is still Unchanged. 
        // The changes to the POCO entity without the chane tracking proxy
        // are not tracked as they occur.
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(order).State);

        // Calls DetectChanges(). The newItem is set to Unchanged.
        context.SaveChanges();

        // Change the newly added item.
        newItem.OrderQty = 2;

        // The state of the newItem is Unchanged.
        // If the newItem was a POCO proxy entity the changes would be tracked as they occur
        // and the state would be Modified.
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State);

        // Call DetectChanges to synchronize the objects with the state manager.
        context.DetectChanges();

        // The state of the newItem is now Modified.
        Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State);

        // Delete the newly created object.
        context.DeleteObject(newItem);

        // Save changes in the object context to the database 
        // after first detecting changes again.
        context.SaveChanges();
    }
    catch (UpdateException ex)
    {
        Console.WriteLine(ex.ToString());
    }
    catch (InvalidOperationException ex)
    {
        Console.WriteLine(ex.ToString());
    }
}

참고 항목

작업

방법: POCO 엔터티 간 관계 변경(Entity Framework)

개념

개체 사용자 지정(Entity Framework)
POCO 엔터티 사용(Entity Framework)