ExtensionDataObject Classe

Définition

Espace de noms:: System.Runtime.Serialization

Assemblys:: netstandard.dll, System.Runtime.Serialization.Xml.dll

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

Assembly:: System.Runtime.Serialization.dll

Assembly:: netstandard.dll

Source:: ExtensionDataObject.cs

Source:: ExtensionDataObject.cs

Source:: ExtensionDataObject.cs

Source:: ExtensionDataObject.cs

Source:: ExtensionDataObject.cs

Important

Certaines informations portent sur la préversion du produit qui est susceptible d’être en grande partie modifiée avant sa publication. Microsoft exclut toute garantie, expresse ou implicite, concernant les informations fournies ici.

Stocke les données à partir d’un contrat de données versionné qui a été étendu en ajoutant de nouveaux membres.

public ref class ExtensionDataObject sealed

public sealed class ExtensionDataObject

type ExtensionDataObject = class

Public NotInheritable Class ExtensionDataObject

Héritage: Object
ExtensionDataObject

Exemples

Le code suivant sérialise une instance d’un type (PersonVersion2) qui est la deuxième version du type sérialisable (Person). La deuxième version contient des données supplémentaires (ID champ) qui ne sont pas présentes dans la première version. Le code désérialise ensuite le document XML dans un Person objet, puis resérialise immédiatement l’objet, y compris les données supplémentaires. Enfin, le code désérialise le nouveau XML dans un PersonVersion2 objet et écrit les données complètes dans la console, montrant que les données ont effectué un aller-retour vers et depuis une version antérieure du type. Notez que l’attribut DataContractAttribute doit être appliqué avec les Name Namespace propriétés définies sur le même nom et le même espace de noms que la classe d’origine.

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

Remarques

Il ExtensionDataObject s’agit de la structure qui stocke des données supplémentaires rencontrées par les XmlObjectSerializer opérations de désérialisation. La structure est utilisée par la sérialisation pour écrire les données supplémentaires dans l’instance sérialisée. La structure est retournée par la ExtensionData propriété de l’interface IExtensibleDataObject .

Méthodes

Nom	Description
Equals(Object)	Détermine si l’objet spécifié est égal à l’objet actuel. (Hérité de Object)
GetHashCode()	Sert de fonction de hachage par défaut. (Hérité de Object)
GetType()	Obtient la Type de l’instance actuelle. (Hérité de Object)
MemberwiseClone()	Crée une copie superficielle du Objectactuel. (Hérité de Object)
ToString()	Retourne une chaîne qui représente l’objet actuel. (Hérité de Object)

S’applique à

Voir aussi

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