ExtensionDataObject Classe

Referência

Definição

Namespace:: System.Runtime.Serialization

Assembly:: System.Runtime.Serialization.Xml.dll

Assembly:: System.Runtime.Serialization.dll

Assembly:: netstandard.dll

Origem:: ExtensionDataObject.cs

Origem:: ExtensionDataObject.cs

Origem:: ExtensionDataObject.cs

Importante

Algumas informações se referem a produtos de pré-lançamento que podem ser substancialmente modificados antes do lançamento. A Microsoft não oferece garantias, expressas ou implícitas, das informações aqui fornecidas.

Armazena dados de um contrato de dados com controle de versão que foi estendido adicionando novos membros.

public ref class ExtensionDataObject sealed

public sealed class ExtensionDataObject

type ExtensionDataObject = class

Public NotInheritable Class ExtensionDataObject

Herança: Object
ExtensionDataObject

Exemplos

O código a seguir serializa uma instância de um tipo (PersonVersion2) que é a segunda versão do tipo serializável (Person). A segunda versão contém dados extras (ID campo) que não estão presentes na primeira versão. Em seguida, o código desserializa o documento XML em um Person objeto e, em seguida, reserializa imediatamente o objeto, incluindo os dados extras. Por fim, o código desserializa o novo XML em um PersonVersion2 objeto e grava os dados completos no console, provando que os dados fizeram uma viagem de ida e volta de e para uma versão mais antiga do tipo. Observe que o DataContractAttribute atributo deve ser aplicado com as Name propriedades e Namespace definidas como o mesmo nome e namespace que a classe original.

using System;
using System.Xml;
using System.Runtime.Serialization;
using System.IO;

// Implement the IExtensibleDataObject interface
// to store the extra data for future versions.
[DataContract(
    Name = "Person",
    Namespace = "http://www.cohowinery.com/employees")]
class Person : IExtensibleDataObject
{
    // To implement the IExtensibleDataObject interface,
    // you must implement the ExtensionData property. The property
    // holds data from future versions of the class for backward
    // compatibility.
    private ExtensionDataObject extensionDataObject_value;
    public ExtensionDataObject ExtensionData
    {
        get
        {
            return extensionDataObject_value;
        }
        set
        {
            extensionDataObject_value = value;
        }
    }
    [DataMember]
    public string Name;
}

// The second version of the class adds a new field. The field's
// data is stored in the ExtensionDataObject field of
// the first version (Person). You must also set the Name property
// of the DataContractAttribute to match the first version.
// If necessary, also set the Namespace property so that the
// name of the contracts is the same.
[DataContract(Name = "Person",
    Namespace = "http://www.cohowinery.com/employees")]
class PersonVersion2 : IExtensibleDataObject
{
    // Best practice: add an Order number to new members.
    [DataMember(Order=2)]
    public int ID;

    [DataMember]
    public string Name;

    private ExtensionDataObject extensionDataObject_value;
    public ExtensionDataObject ExtensionData
    {
        get
        {
            return extensionDataObject_value;
        }
        set
        {
            extensionDataObject_value = value;
        }
    }
}
public sealed class Program
{
    private Program()
    {
        // Private constructor to prevent creation of this class.
    }

    public static void Main()
    {
        try
        {
            WriteVersion2("V2.xml");
            WriteToVersion1("v2.xml");
            ReadVersion2("v2.xml");
        }
        catch (SerializationException exc)
        {
            Console.WriteLine("{0}: {1}", exc.Message, exc.StackTrace);
        }
        finally
        {
            Console.ReadLine();
        }
    }

    // Create an instance of the version 2.0 class. It has
    // extra data (ID field) that version 1.0 does
    // not understand.
    static void WriteVersion2(string path)
    {
        Console.WriteLine("Creating a version 2 object");
        PersonVersion2 p2 = new PersonVersion2();
        p2.Name = "Elizabeth";
        p2.ID = 2006;

        Console.WriteLine("Object data includes an ID");
        Console.WriteLine("\t Name: {0}", p2.Name);
        Console.WriteLine("\t ID: {0} \n", p2.ID);
        // Create an instance of the DataContractSerializer.
        DataContractSerializer ser =
            new DataContractSerializer(typeof(PersonVersion2));

        Console.WriteLine("Serializing the v2 object to a file. \n\n");
        FileStream fs = new FileStream(path, FileMode.Create);
        ser.WriteObject(fs, p2);
        fs.Close();
    }

    // Deserialize version 2 data to a version 1 object.
    static void WriteToVersion1(string path)
    {
        // Create the serializer using the version 1 type.
        DataContractSerializer ser =
            new DataContractSerializer(typeof(Person));

        FileStream fs = new FileStream(path, FileMode.Open);
        XmlDictionaryReader reader =
           XmlDictionaryReader.CreateTextReader(fs, new XmlDictionaryReaderQuotas());
        Console.WriteLine
            ("Deserializing v2 data to v1 object. \n\n");

        Person p1 = (Person)ser.ReadObject(reader, false);

        Console.WriteLine("V1 data has only a Name field.");
        Console.WriteLine("But the v2 data is stored in the ");
        Console.WriteLine("ExtensionData property. \n\n");
        Console.WriteLine("\t Name: {0} \n", p1.Name);

        fs.Close();

        // Change data in the object.
        p1.Name = "John";
        Console.WriteLine("Changed the Name value to 'John' ");
        Console.Write("and reserializing the object to version 2 \n\n");
        // Reserialize the object.
        fs = new FileStream(path, FileMode.Create);
        ser.WriteObject(fs, p1);
        fs.Close();
    }

    // Deserialize a version 2.0 object.
    public static void ReadVersion2(string path)
    {
        FileStream fs = new FileStream(path, FileMode.Open);
        DataContractSerializer ser = new DataContractSerializer(typeof(PersonVersion2));

        Console.WriteLine("Deserializing new data to version 2 \n\n");
        PersonVersion2 p2 = (PersonVersion2)ser.ReadObject(fs);
        fs.Close();

        Console.WriteLine("The data includes the old ID field value. \n");
        Console.WriteLine("\t (New) Name: {0}", p2.Name);
        Console.WriteLine("\t ID: {0} \n", p2.ID);
    }
}

' Implement the IExtensibleDataObject interface 
' to store the extra data for future versions.
<DataContract(Name := "Person", [Namespace] := "http://www.cohowinery.com/employees")>  _
Class Person
    Implements IExtensibleDataObject
    ' To implement the IExtensibleDataObject interface,
    ' you must implement the ExtensionData property. The property
    ' holds data from future versions of the class for backward
    ' compatibility.
    Private extensionDataObject_value As ExtensionDataObject
    
    Public Property ExtensionData() As ExtensionDataObject _
       Implements IExtensibleDataObject.ExtensionData
        Get
            Return extensionDataObject_value
        End Get
        Set
            extensionDataObject_value = value
        End Set
    End Property
    <DataMember()>  _
    Public Name As String
End Class 

' The second version of the class adds a new field. The field's 
' data is stored in the ExtensionDataObject field of
' the first version (Person). You must also set the Name property 
' of the DataContractAttribute to match the first version. 
' If necessary, also set the Namespace property so that the 
' name of the contracts is the same.

<DataContract(Name := "Person", [Namespace] := "http://www.cohowinery.com/employees")>  _
Class PersonVersion2
    Implements IExtensibleDataObject

    ' Best practice: add an Order number to new members.
    <DataMember(Order:=2)>  _
    Public ID As Integer
    
    <DataMember()>  _
    Public Name As String
    
    Private extensionDataObject_value As ExtensionDataObject
    
    Public Property ExtensionData() As ExtensionDataObject _
       Implements IExtensibleDataObject.ExtensionData
        Get
            Return extensionDataObject_value
        End Get
        Set
            extensionDataObject_value = value
        End Set
    End Property
End Class 

NotInheritable Public Class Program

    ' Private constructor to prevent creation of this class.
    Private Sub New() 
    
    End Sub 
    
    
    Public Shared Sub Main() 
        Try
            WriteVersion2("V2.xml")
            WriteToVersion1("v2.xml")
            ReadVersion2("v2.xml")
        Catch exc As SerializationException
            Console.WriteLine("{0}: {1}", exc.Message, exc.StackTrace)
        Finally
            Console.ReadLine()
        End Try
    
    End Sub 
    
    ' Create an instance of the version 2.0 class. It has  
    ' extra data (ID field) that version 1.0 does 
    ' not understand.
    Shared Sub WriteVersion2(ByVal path As String) 
        Console.WriteLine("Creating a version 2 object")
        Dim p2 As New PersonVersion2()
        p2.Name = "Elizabeth"
        p2.ID = 2006
        
        Console.WriteLine("Object data includes an ID")
        Console.WriteLine(vbTab + " Name: {0}", p2.Name)
        Console.WriteLine(vbTab + " ID: {0} " + vbLf, p2.ID)
        ' Create an instance of the DataContractSerializer.
        Dim ser As New DataContractSerializer(GetType(PersonVersion2))
        
        Console.WriteLine("Serializing the v2 object to a file. " + vbLf + vbLf)
        Dim fs As New FileStream(path, FileMode.Create)
        ser.WriteObject(fs, p2)
        fs.Close()
    End Sub 
    
    ' Deserialize version 2 data to a version 1 object.
    Shared Sub WriteToVersion1(ByVal path As String) 
        ' Create the serializer using the version 1 type.
        Dim ser As New DataContractSerializer(GetType(Person))
        
        Dim fs As New FileStream(path, FileMode.Open)
        Dim reader As XmlDictionaryReader = _
            XmlDictionaryReader.CreateTextReader(fs, New XmlDictionaryReaderQuotas())
        Console.WriteLine("Deserializing v2 data to v1 object. " + vbLf + vbLf)
        
        Dim p1 As Person = CType(ser.ReadObject(reader, False), Person)
        
        Console.WriteLine("V1 data has only a Name field.")
        Console.WriteLine("But the v2 data is stored in the ")
        Console.WriteLine("ExtensionData property. " + vbLf + vbLf)
        Console.WriteLine(vbTab + " Name: {0} " + vbLf, p1.Name)
        
        reader.Close()
        fs.Close()
        
        ' Change data in the object.
        p1.Name = "John"
        Console.WriteLine("Changed the Name value to 'John' ")
        Console.Write("and reserializing the object to version 2 " + vbLf + vbLf)
        ' Reserialize the object.
        fs = New FileStream(path, FileMode.Create)
        ser.WriteObject(fs, p1)
        fs.Close()
    
    End Sub 
    
    ' Deserialize a version 2.0 object. 
    Public Shared Sub ReadVersion2(ByVal path As String) 
        Dim fs As New FileStream(path, FileMode.Open)
        Dim ser As New DataContractSerializer(GetType(PersonVersion2))
        
        Console.WriteLine("Deserializing new data to version 2 " + vbLf + vbLf)
        Dim p2 As PersonVersion2 = CType(ser.ReadObject(fs), PersonVersion2)
        fs.Close()
        
        Console.WriteLine("The data includes the old ID field value. " + vbLf)
        Console.WriteLine(vbTab + " (New) Name: {0}", p2.Name)
        Console.WriteLine(vbTab + " ID: {0} " + vbLf, p2.ID)
    
    End Sub 
End Class

Comentários

O ExtensionDataObject é a estrutura que armazena dados extras encontrados pelo XmlObjectSerializer durante operações de desserialização. A estrutura é usada pela serialização para gravar os dados extras na instância serializada. A estrutura é retornada pela ExtensionData propriedade da IExtensibleDataObject interface .

Métodos

Equals(Object)	Determina se o objeto especificado é igual ao objeto atual. (Herdado de Object)
GetHashCode()	Serve como a função de hash padrão. (Herdado de Object)
GetType()	Obtém o Type da instância atual. (Herdado de Object)
MemberwiseClone()	Cria uma cópia superficial do Object atual. (Herdado de Object)
ToString()	Retorna uma cadeia de caracteres que representa o objeto atual. (Herdado de Object)

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