DataMemberAttribute Classe

Definição

public ref class DataMemberAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property, AllowMultiple=false, Inherited=false)]
public sealed class DataMemberAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property, AllowMultiple=false, Inherited=false)>]
type DataMemberAttribute = class
    inherit Attribute

Public NotInheritable Class DataMemberAttribute
Inherits Attribute

Herança

Object

Attribute

DataMemberAttribute

Atributos

AttributeUsageAttribute

Exemplos

O exemplo seguinte mostra um tipo ao qual os DataContractAttribute atributos e DataMemberAttribute foram aplicados. A Name propriedade no DataMemberAttribute está definida como "ID".

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

// You must apply a DataContractAttribute or SerializableAttribute
// to a class to have it serialized by the DataContractSerializer.
[DataContract()]
class Person : IExtensibleDataObject
{
    private string LastNameValue;
    // Apply the DataMemberAttribute to fields (or properties)
    // that must be serialized.
    [DataMember()]
    public string FirstName;

    [DataMember]
    public string LastName
    {
        get { return LastNameValue; }
        set { LastNameValue = value; }
    }

    [DataMember(Name = "ID")]
    public int IdNumber;

    // Note that you can apply the DataMemberAttribute to
    // a private field as well.
    [DataMember]
    private string Secret;

    public Person(string newfName, string newLName, int newIdNumber)
    {
        FirstName = newfName;
        LastName = newLName;
        IdNumber = newIdNumber;
        Secret = newfName + newLName + newIdNumber;
    }

    // The extensionDataValue field holds data from future versions
    // of the type.  This enables this type to be compatible with
    // future versions. The field is required to implement the
    // IExtensibleDataObject interface.

    private ExtensionDataObject extensionDatavalue;

    public ExtensionDataObject ExtensionData
    {
        get
        {
            return extensionDatavalue;
        }
        set
        {
            extensionDatavalue = value;
        }
    }
}

public class Test
{
    public static void Main(string[] args)
    {
        try
        {
            WriteObject(@"DataMemberAttributeExample.xml");
            ReadObject(@"DataMemberAttributeExample.xml");
        }
        catch (Exception exc)
        {
            Console.WriteLine(
            "The serialization operation failed: {0} StackTrace: {1}",
            exc.Message, exc.StackTrace);
        }
        finally
        {
            Console.WriteLine("Press <Enter> to exit....");
            Console.ReadLine();
        }
    }

    public static void WriteObject(string filename)
    {
        // Create a new instance of the Person class.
        Person p1 = new Person("Zighetti", "Barbara", 101);
        FileStream writer = new FileStream(filename,
        FileMode.OpenOrCreate);
        DataContractSerializer ser =
            new DataContractSerializer(typeof(Person));
        ser.WriteObject(writer, p1);
        writer.Close();
    }

    public static void ReadObject(string filename)
    {
        // Deserialize an instance of the Person class
        // from an XML file.
        FileStream fs = new FileStream(filename,
        FileMode.OpenOrCreate);
        DataContractSerializer ser =
            new DataContractSerializer(typeof(Person));
        // Deserialize the data and read it from the instance.
        Person deserializedPerson = (Person)ser.ReadObject(fs);
        fs.Close();
        Console.WriteLine(String.Format("{0} {1}, ID: {2}",
        deserializedPerson.FirstName, deserializedPerson.LastName,
        deserializedPerson.IdNumber));
    }
}

Imports System.Collections
Imports System.IO
Imports System.Runtime.Serialization
Imports System.Xml

' You must apply a DataContractAttribute or SerializableAttribute
' to a class to have it serialized by the DataContractSerializer.
<DataContract()>  _
Class Person
    Implements IExtensibleDataObject

    Private LastNameValue As String
     
    ' Apply the DataMemberAttribute to fields (or properties) 
    ' that must be serialized.
    
    <DataMember()>  _
    Public FirstName As String
    
    <DataMember()>  _
    Public Property LastName() As String
        Get
            Return LastNameValue 
        End Get

        Set(ByVal Value As String)
           LastNameValue = Value
        End Set
    End Property

    
    <DataMember(Name:="ID")>  _
    Public IdNumber As Integer
    
    ' Note that you can apply the DataMemberAttribute to 
    ' a private field as well.
    <DataMember()>  _
    Private Secret As String
    
    Public Sub New(ByVal newfName As String, ByVal newLName As String, ByVal newIdNumber As Integer) 
        FirstName = newfName
        LastName = newLName
        IdNumber = newIdNumber
        Secret = newfName + newLName + newIdNumber.ToString()
    
    End Sub 
    
    ' The ExtensionData field holds data from future versions 
    ' of the type.  This enables this type to be compatible with 
    ' future versions. The field is required to implement the 
    ' IExtensibleObjectData interface.
    Private extensionDataValue As ExtensionDataObject
    
    Public Property ExtensionData() As ExtensionDataObject _
       Implements IExtensibleDataObject.ExtensionData
        Get
            Return extensionDataValue
        End Get
        Set
            extensionDataValue = value
        End Set
    End Property
End Class 

Public Class Test
    Public Shared Sub Main(ByVal args() As String) 
        Try
            ReadObject("DataMemberAttributeExample.xml")
            WriteObject("DataMemberAttributeExample.xml")
        Catch exc As Exception
            Console.WriteLine("The serialization operation failed: {0} StackTrace: {1}", _
            exc.Message, exc.StackTrace)
        Finally
            Console.WriteLine("Press <Enter> to exit....")
            Console.ReadLine()
        End Try
    End Sub 
    
    Public Shared Sub ReadObject(ByVal filename As String) 
        ' Create a new instance of the Person class.
        Dim p1 As New Person("Zighetti", "Barbara", 101)
        Dim writer As New FileStream(filename, FileMode.Create)
        Dim ser As New DataContractSerializer(GetType(Person))
        ser.WriteObject(writer, p1)
        writer.Close()
    End Sub 

    Public Shared Sub WriteObject(ByVal filename As String) 
        ' Deserialize an instance of the Person class 
        ' from an XML file.
        Dim fs As New FileStream(filename, FileMode.OpenOrCreate)
        Dim ser As New DataContractSerializer(getTYpe(Person))
        ' Deserialize the data and read it from the instance.
        Dim deserializedPerson As Person = ser.ReadObject(fs)
        fs.Close()
        Console.WriteLine(String.Format("{0} {1}, ID: {2}", _
        deserializedPerson.FirstName, deserializedPerson.LastName, deserializedPerson.IdNumber))
    End Sub 
End Class

Observações

Aplique o DataMemberAttribute atributo em conjunto com o DataContractAttribute para identificar membros de um tipo que fazem parte de um contrato de dados. Um dos serializadores que pode serializar contratos de dados é o DataContractSerializer.

O modelo de contrato de dados é um modelo "opt-in". Aplicar o DataMemberAttribute a um campo ou propriedade especifica explicitamente que o valor do membro será serializado. Em contraste, serializa XmlSerializer todos os corpos públicos e propriedades de um tipo.

Por defeito, o nome do membro CLR é usado como nome do membro de dados. Ao definir a Name propriedade, pode personalizar o nome do membro de dados. Isto pode ser usado para fornecer um nome que pode não ser permitido como nome de membro do CLR. Ao mapear para XML usando o DataContractSerializer, este nome é usado como nome do elemento do esquema num tipo.

Para mais informações sobre contratos de dados e membros de dados, consulte Utilização de Contratos de Dados. Para mais informações sobre nomes de membros, consulte Valores Padrão de Membros de Dados.

Ver também

• DataContractAttribute
• DataContractSerializer
• IExtensibleDataObject
• Usando contratos de dados
• Práticas recomendadas: Controle de versão de contrato de dados
• Valores padrão do membro de dados
• Pedido de Membro de Dados