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HOW TO:使用 EntityConnection 搭配物件內容 (Entity Framework)

本主題提供的範例將示範如何提供現有的 EntityConnection 給即將使用的物件內容。 如需詳細資訊,請參閱管理物件內容 (Entity Framework)

本主題的範例是根據 AdventureWorks Sales Model (EDM)。 若要執行此範例中的程式碼,您必須已經將 AdventureWorks Sales Model 加入到專案中,並設定您的專案使用 Entity Framework。 若要這樣做,請完成 HOW TO:使用 Entity Data Model 精靈 (Entity Framework) 中的程序。

範例

這個範例會建立 EntityConnection,然後將它傳遞至長時間執行之 ObjectContext 的建構函式 (Constructor) 中。 連接已手動開啟。 EntityConnectionObjectContext 則已手動處置 (Dispose)。

' Define the order ID for the order we want.
Dim orderId As Integer = 43661

' Create an EntityConnection.
Dim conn As New EntityConnection("name=AdventureWorksEntities")

' Create a long-running context with the connection.
Dim advWorksContext As New AdventureWorksEntities(conn)

Try
    ' Explicitly open the connection.
    If Not conn.State = ConnectionState.Open Then
        conn.Open()
    End If

    ' Execute a query to return an order.
    Dim order As SalesOrderHeader = _
        advWorksContext.SalesOrderHeader.Where( _
        "it.SalesOrderID = @orderId", New ObjectParameter("orderId", orderId)) _
        .Execute(MergeOption.AppendOnly).First()

    ' Change the status of the order.
    order.Status = 1

    ' Save changes.
    If 0 < advWorksContext.SaveChanges() Then
        Console.WriteLine("Changes saved.")
    End If

    ' Load the order's items.
    order.SalesOrderDetail.Load()

    ' Delete the first item.
    advWorksContext _
        .DeleteObject(order.SalesOrderDetail.First())

    ' Save changes again.
    If 0 < advWorksContext.SaveChanges() Then
        Console.WriteLine("Changes saved.")
    End If
Catch ex As InvalidOperationException
    Console.WriteLine(ex.ToString())
Finally
    ' Explicitly dispose of the context and the connection. 
    advWorksContext.Dispose()
    conn.Dispose()
End Try
// Define the order ID for the order we want.
int orderId = 43661;

// Create an EntityConnection.
EntityConnection conn =
    new EntityConnection("name=AdventureWorksEntities");

// Create a long-running context with the connection.
AdventureWorksEntities advWorksContext =
    new AdventureWorksEntities(conn);

try
{
    // Explicitly open the connection.
    if (conn.State != ConnectionState.Open)
    {
        conn.Open();
    }

    // Execute a query to return an order.
    SalesOrderHeader order =
        advWorksContext.SalesOrderHeader.Where(
        "it.SalesOrderID = @orderId", new ObjectParameter("orderId", orderId))
        .Execute(MergeOption.AppendOnly).First();

    // Change the status of the order.
    order.Status = 1;

    // Save changes.
    if (0 < advWorksContext.SaveChanges())
    {
        Console.WriteLine("Changes saved.");
    }

    // Load the order's items.
    order.SalesOrderDetail.Load();

    // Delete the first item.
    advWorksContext
        .DeleteObject(order.SalesOrderDetail.First());

    // Save changes again.
    if (0 < advWorksContext.SaveChanges())
    {
        Console.WriteLine("Changes saved.");
    }
}
catch (InvalidOperationException ex)
{
    Console.WriteLine(ex.ToString());
}
finally
{
    // Explicitly dispose of the context and the connection. 
    advWorksContext.Dispose();
    conn.Dispose();
}

另請參閱

工作

HOW TO:在長時間執行的物件內容中管理連接 (Entity Framework)
HOW TO:從物件內容手動開啟連接 (Entity Framework)