オブジェクトをシリアル化およびシリアル化解除する方法 (Entity Framework)
エンティティ データ モデル (EDM) ジェネレータ ツール (EdmGen.exe) と Entity Data Model ウィザードによって生成されたエンティティ型は、バイナリ シリアル化をサポートしています。オブジェクトをバイナリ ストリームにシリアル化した場合、現在オブジェクト コンテキストに読み込まれている、関連するすべてのオブジェクトもシリアル化されます。詳細については、「オブジェクトのシリアル化 (Entity Framework)」を参照してください。
このトピックの例には、Adventure Works Sales Model が使用されています。この例のコードを実行するには、あらかじめプロジェクトに AdventureWorks Sales Model を追加し、Entity Framework を使用するようにプロジェクトを構成しておく必要があります。具体的な方法については、「Entity Framework プロジェクトを手動で構成する方法」および「Entity Data Model を手動で定義する方法 (Entity Framework)」の手順を参照してください。さらに、次の名前空間の using ステートメント (Visual Basic の場合は Imports) を追加する必要があります。
例
この例では、SerializeToBinaryStream メソッドに特定の姓の値を指定して Contact オブジェクトを照会し、バイナリの MemoryStream を取得しています。MemoryStream には、Contact オブジェクトと、それに関連する SalesOrderHeader オブジェクトおよび SalesOrderDetail オブジェクトのオブジェクト グラフが格納されます。
Public Shared Sub ReadFromBinaryStream()
Dim formatter As New BinaryFormatter
Using context As New AdventureWorksEntities()
Try
' Get the object graph for the selected customer
' as a binary stream.
Dim stream As MemoryStream = SerializeToBinaryStream("Adams")
' Read from the begining of the stream.
stream.Seek(0, SeekOrigin.Begin)
' Deserialize the customer graph from the binary stream
' and attach to an ObjectContext.
Dim contact As Contact = CType(formatter.Deserialize(stream), Contact)
context.Attach(contact)
' Display information for each item
' in the orders that belong to the contact.
For Each order As SalesOrderHeader In contact.SalesOrderHeader
Console.WriteLine(String.Format("PO Number: {0}", _
order.PurchaseOrderNumber))
Console.WriteLine(String.Format("Order Date: {0}", _
order.OrderDate.ToString()))
Console.WriteLine("Order items:")
For Each item As SalesOrderDetail In order.SalesOrderDetail
Console.WriteLine(String.Format("Product:{0}" _
+ "Quantity: {1}", item.ProductID.ToString(), _
item.OrderQty.ToString()))
Next
Next
Catch ex As ApplicationException
Console.WriteLine(ex.ToString())
Catch ex As SerializationException
Console.WriteLine("The object graph could not be deserialized from " _
+ "the binary stream because of the following error:")
Console.WriteLine(ex.ToString())
End Try
End Using
End Sub
Private Shared Function SerializeToBinaryStream(ByVal lastName As String) As MemoryStream
Dim formatter As BinaryFormatter = New BinaryFormatter()
Dim stream As MemoryStream = New MemoryStream()
Using context As New AdventureWorksEntities
' Specify a timeout for queries in this context, in seconds.
context.CommandTimeout = 120
' Define a customer contact.
Dim customer As Contact
' Create a Contact query with a path that returns orders and items for a contact.
Dim query As ObjectQuery(Of Contact) = _
context.Contact '.Include("SalesOrderHeader.SalesOrderDetail")
Try
' Return the first contact with the specified last name
' along with its related orders and items.
customer = query.Where( _
"it.LastName = @lastname", _
New ObjectParameter("lastname", lastName)).First()
' Serialize the customer object graph.
formatter.Serialize(stream, customer)
Catch ex As EntitySqlException
Throw New ApplicationException("The object query failed", ex)
Catch ex As EntityCommandExecutionException
Throw New ApplicationException("The object query failed", ex)
Catch ex As SerializationException
Throw New ApplicationException("The object graph could not be serialized", ex)
End Try
' Return the streamed object graph.
Return stream
End Using
End Function
public static void ReadFromBinaryStream()
{
BinaryFormatter formatter = new BinaryFormatter();
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
try
{
// Get the object graph for the selected customer
// as a binary stream.
MemoryStream stream = SerializeToBinaryStream(@"Adams");
// Read from the begining of the stream.
stream.Seek(0, SeekOrigin.Begin);
// Deserialize the customer graph from the binary stream
// and attach to an ObjectContext.
Contact contact = (Contact)formatter.Deserialize(stream);
context.Attach(contact);
// Display information for each item
// in the orders that belong to the first contact.
foreach (SalesOrderHeader order in contact.SalesOrderHeader)
{
Console.WriteLine(String.Format("PO Number: {0}",
order.PurchaseOrderNumber));
Console.WriteLine(String.Format("Order Date: {0}",
order.OrderDate.ToString()));
Console.WriteLine("Order items:");
foreach (SalesOrderDetail item in order.SalesOrderDetail)
{
Console.WriteLine(String.Format("Product: {0} "
+ "Quantity: {1}", item.ProductID.ToString(),
item.OrderQty.ToString()));
}
}
}
catch (ApplicationException ex)
{
Console.WriteLine(ex.ToString());
}
catch (SerializationException ex)
{
Console.WriteLine("The object graph could not be deserialized from "
+ "the binary stream because of the following error:");
Console.WriteLine(ex.ToString());
}
}
}
private static MemoryStream SerializeToBinaryStream(string lastName)
{
BinaryFormatter formatter = new BinaryFormatter();
MemoryStream stream = new MemoryStream();
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
// Specify a timeout for queries in this context, in seconds.
context.CommandTimeout = 120;
// Define a customer contact.
Contact customer;
// Create a Contact query with a path that returns
// orders and items for a contact.
ObjectQuery<Contact> query =
context.Contact.Include("SalesOrderHeader.SalesOrderDetail");
try
{
// Return the first contact with the specified last name
// along with its related orders and items.
customer = query.Where("it.LastName = @lastname",
new ObjectParameter("lastname", lastName)).First();
// Serialize the customer object graph.
formatter.Serialize(stream, customer);
}
catch (EntitySqlException ex)
{
throw new ApplicationException("The object query failed", ex);
}
catch (EntityCommandExecutionException ex)
{
throw new ApplicationException("The object query failed", ex);
}
catch (SerializationException ex)
{
throw new ApplicationException("The object graph could not be serialized", ex);
}
// Return the streamed object graph.
return stream;
}
}