DataContractSerializer Class

Definition

Namespace:

System.Runtime.Serialization

Assembly:

System.Runtime.Serialization.Xml.dll

Serializes and deserializes an instance of a type into an XML stream or document using a supplied data contract. This class cannot be inherited.

public ref class DataContractSerializer sealed : System::Runtime::Serialization::XmlObjectSerializer

public sealed class DataContractSerializer : System.Runtime.Serialization.XmlObjectSerializer

type DataContractSerializer = class
    inherit XmlObjectSerializer

Public NotInheritable Class DataContractSerializer
Inherits XmlObjectSerializer

Inheritance

Object

XmlObjectSerializer

DataContractSerializer

Examples

The following example code shows a type named Person that is serialized by the DataContractSerializer. The DataContractAttribute attribute is applied to the class, and the DataMemberAttribute is applied to members to instruct the DataContractSerializer what to serialize.

namespace DataContractSerializerExample
{
    using System;
    using System.Collections;
    using System.Collections.Generic;
    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(Name = "Customer", Namespace = "http://www.contoso.com")]
    class Person : IExtensibleDataObject
    {
        [DataMember()]
        public string FirstName;
        [DataMember]
        public string LastName;
        [DataMember()]
        public int ID;

        public Person(string newfName, string newLName, int newID)
        {
            FirstName = newfName;
            LastName = newLName;
            ID = newID;
        }

        private ExtensionDataObject extensionData_Value;

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

    public sealed class Test
    {
        private Test() { }

        public static void Main()
        {
            try
            {
                WriteObject("DataContractSerializerExample.xml");
                ReadObject("DataContractSerializerExample.xml");
            }

            catch (SerializationException serExc)
            {
                Console.WriteLine("Serialization Failed");
                Console.WriteLine(serExc.Message);
            }
            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)
        {
            Console.WriteLine(
                "Creating a Person object and serializing it.");
            Person p1 = new Person("Zighetti", "Barbara", 101);
            FileStream writer = new FileStream(fileName, FileMode.Create);
            DataContractSerializer ser =
                new DataContractSerializer(typeof(Person));
            ser.WriteObject(writer, p1);
            writer.Close();
        }

        public static void ReadObject(string fileName)
        {
            Console.WriteLine("Deserializing an instance of the object.");
            FileStream fs = new FileStream(fileName,
            FileMode.Open);
            XmlDictionaryReader reader =
                XmlDictionaryReader.CreateTextReader(fs, new XmlDictionaryReaderQuotas());
            DataContractSerializer ser = new DataContractSerializer(typeof(Person));

            // Deserialize the data and read it from the instance.
            Person deserializedPerson =
                (Person)ser.ReadObject(reader, true);
            reader.Close();
            fs.Close();
            Console.WriteLine(String.Format("{0} {1}, ID: {2}",
            deserializedPerson.FirstName, deserializedPerson.LastName,
            deserializedPerson.ID));
        }
    }

' You must apply a DataContractAttribute or SerializableAttribute
' to a class to have it serialized by the DataContractSerializer.
<DataContract(Name := "Customer", [Namespace] := "http://www.contoso.com")>  _
Class Person
    Implements IExtensibleDataObject
    <DataMember()>  _
    Public FirstName As String
    <DataMember()>  _
    Public LastName As String
    <DataMember()>  _
    Public ID As Integer
    
    Public Sub New(ByVal newfName As String, ByVal newLName As String, ByVal newID As Integer) 
        FirstName = newfName
        LastName = newLName
        ID = newID
    End Sub 
    
    Private extensionData_Value As ExtensionDataObject
    
    Public Property ExtensionData() As ExtensionDataObject Implements _
       IExtensibleDataObject.ExtensionData
        Get
            Return extensionData_Value
        End Get
        Set
            extensionData_Value = value
        End Set
    End Property
End Class 


NotInheritable Public Class Test
    
    Private Sub New() 
    
    End Sub 
     
    Public Shared Sub Main() 
        Try
            WriteObject("DataContractSerializerExample.xml")
            ReadObject("DataContractSerializerExample.xml")
        
        Catch serExc As SerializationException
            Console.WriteLine("Serialization Failed")
            Console.WriteLine(serExc.Message)
        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 WriteObject(ByVal fileName As String) 
        Console.WriteLine("Creating a Person object and serializing it.")
        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 ReadObject(ByVal fileName As String) 
        Console.WriteLine("Deserializing an instance of the object.")
        Dim fs As New FileStream(fileName, FileMode.Open)
        Dim reader As XmlDictionaryReader = _
            XmlDictionaryReader.CreateTextReader(fs, New XmlDictionaryReaderQuotas())
        Dim ser As New DataContractSerializer(GetType(Person))
        
        ' Deserialize the data and read it from the instance.
        Dim deserializedPerson As Person = CType(ser.ReadObject(reader, True), Person)
        reader.Close()
        fs.Close()
        Console.WriteLine(String.Format("{0} {1}, ID: {2}", deserializedPerson.FirstName, deserializedPerson.LastName, deserializedPerson.ID))
    End Sub 
End Class

Remarks

Use the DataContractSerializer class to serialize and deserialize instances of a type into an XML stream or document. For example, you can create a type named Person with properties that contain essential data, such as a name and address. You can then create and manipulate an instance of the Person class and write all of its property values in an XML document for later retrieval, or in an XML stream for immediate transport. Most important, the DataContractSerializer is used to serialize and deserialize data sent in Windows Communication Foundation (WCF) messages. Apply the DataContractAttribute attribute to classes, and the DataMemberAttribute attribute to class members to specify properties and fields that are serialized.

For a list of types that can be serialized, see Types Supported by the Data Contract Serializer.

To use the DataContractSerializer, first create an instance of a class and an object appropriate to writing or reading the format; for example, an instance of the XmlDictionaryWriter. Then call the WriteObject method to persist the data. To retrieve data, create an object appropriate to reading the data format (such as an XmlDictionaryReader for an XML document) and call the ReadObject method.

For more information about using the DataContractSerializer, see Serialization and Deserialization.

You can set the type of a data contract serializer using the <dataContractSerializer> element in a client application configuration file.

Preparing Classes for Serialization or Deserialization

The DataContractSerializer is used in combination with the DataContractAttribute and DataMemberAttribute classes. To prepare a class for serialization, apply the DataContractAttribute to the class. For each member of the class that returns data that you want to serialize, apply the DataMemberAttribute. You can serialize fields and properties, regardless of accessibility: private, protected, internal, protected internal, or public.

For example, your schema specifies a Customer with an ID property, but you already have an existing application that uses a type named Person with a Name property. To create a type that conforms to the contract, first apply the DataContractAttribute to the class. Then apply the DataMemberAttribute to every field or property that you want to serialize.

Note

You can apply the DataMemberAttribute to both private and public members.

The final format of the XML need not be text. Instead, the DataContractSerializer writes the data as an XML infoset, which allows you to write the data to any format recognized by the XmlReader and XmlWriter. It is recommended that you use the XmlDictionaryReader and XmlDictionaryWriter classes to read and write, because both are optimized to work with the DataContractSerializer.

If you are creating a class that has fields or properties that must be populated before the serialization or deserialization occurs, use callback attributes, as described in Version-Tolerant Serialization Callbacks.

Adding to the Collection of Known Types

When serializing or deserializing an object, it is required that the type is "known" to the DataContractSerializer. Begin by creating an instance of a class that implements IEnumerable<T> (such as List<T>) and adding the known types to the collection. Then create an instance of the DataContractSerializer using one of the overloads that takes the IEnumerable<T> (for example, DataContractSerializer(Type, IEnumerable<Type>).

Note

Unlike other primitive types, the DateTimeOffset structure is not a known type by default, so it must be manually added to the list of known types (see Data Contract Known Types).

Forward Compatibility

The DataContractSerializer understands data contracts that have been designed to be compatible with future versions of the contract. Such types implement the IExtensibleDataObject interface. The interface features the ExtensionData property that returns an ExtensionDataObject object. For more information, see Forward-Compatible Data Contracts.

Running under Partial Trust

When instantiating the target object during deserialization, the DataContractSerializer does not call the constructor of the target object. If you author a [DataContract] type that is accessible from partial trust (that is, it is public and in an assembly that has the AllowPartiallyTrustedCallers attribute applied) and that performs some security-related actions, you must be aware that the constructor is not called. In particular, the following techniques do not work:

• If you try to restrict partial trust access by making the constructor internal or private, or by adding a LinkDemand to the constructor -- neither of these have any effect during deserialization under partial trust.

• If you code the class that assumes the constructor has run, the class may get into an invalid internal state that is exploitable.

Constructors

DataContractSerializer(Type)	Initializes a new instance of the DataContractSerializer class to serialize or deserialize an object of the specified type.
DataContractSerializer(Type, DataContractSerializerSettings)	Initializes a new instance of the DataContractSerializer class to serialize or deserialize an object of the specified type and settings.
DataContractSerializer(Type, IEnumerable<Type>)	Initializes a new instance of the DataContractSerializer class to serialize or deserialize an object of the specified type, and a collection of known types that may be present in the object graph.
DataContractSerializer(Type, String, String)	Initializes a new instance of the DataContractSerializer class to serialize or deserialize an object of the specified type using the supplied XML root element and namespace.
DataContractSerializer(Type, String, String, IEnumerable<Type>)	Initializes a new instance of the DataContractSerializer class to serialize or deserialize an object of the specified type. This method also specifies the root XML element and namespace in two string parameters as well as a list of known types that may be present in the object graph.
DataContractSerializer(Type, XmlDictionaryString, XmlDictionaryString)	Initializes a new instance of the DataContractSerializer class to serialize or deserialize an object of the specified type using the XML root element and namespace specified through the parameters of type XmlDictionaryString.
DataContractSerializer(Type, XmlDictionaryString, XmlDictionaryString, IEnumerable<Type>)	Initializes a new instance of the DataContractSerializer class to serialize or deserialize an object of the specified type. This method also specifies the root XML element and namespace in two XmlDictionaryString parameters as well as a list of known types that may be present in the object graph.

Properties

DataContractResolver	Gets the component used to dynamically map xsi:type declarations to known contract types.
IgnoreExtensionDataObject	Gets a value that specifies whether to ignore data supplied by an extension of the class when the class is being serialized or deserialized.
KnownTypes	Gets a collection of types that may be present in the object graph serialized using this instance of the DataContractSerializer.
MaxItemsInObjectGraph	Gets the maximum number of items in an object graph to serialize or deserialize.
PreserveObjectReferences	Gets a value that specifies whether to use non-standard XML constructs to preserve object reference data.
SerializeReadOnlyTypes	Gets a value that specifies whether read-only types are serialized.

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsStartObject(XmlDictionaryReader)	Determines whether the XmlDictionaryReader is positioned on an object that can be deserialized.
IsStartObject(XmlReader)	Determines whether the XmlReader is positioned on an object that can be deserialized.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ReadObject(Stream)	Reads the XML stream or document with a Stream and returns the deserialized object. (Inherited from XmlObjectSerializer)
ReadObject(XmlDictionaryReader)	Reads the XML document or stream with an XmlDictionaryReader and returns the deserialized object. (Inherited from XmlObjectSerializer)
ReadObject(XmlDictionaryReader, Boolean)	Reads the XML stream with an XmlDictionaryReader and returns the deserialized object, and also specifies whether a check is made to verify the object name before reading its value.
ReadObject(XmlDictionaryReader, Boolean, DataContractResolver)	Reads an XML document or document stream and returns the deserialized object. The method includes a parameter to specify whether the object name is verified is validated, and a resolver for mapping xsi:type declarations at runtime.
ReadObject(XmlReader)	Reads the XML stream with an XmlReader and returns the deserialized object.
ReadObject(XmlReader, Boolean)	Reads the XML stream with an XmlReader and returns the deserialized object, and also specifies whether a check is made to verify the object name before reading its value.
ToString()	Returns a string that represents the current object. (Inherited from Object)
WriteEndObject(XmlDictionaryWriter)	Writes the closing XML element using an XmlDictionaryWriter.
WriteEndObject(XmlWriter)	Writes the closing XML element using an XmlWriter.
WriteObject(Stream, Object)	Writes the complete content (start, content, and end) of the object to the XML document or stream with the specified Stream. (Inherited from XmlObjectSerializer)
WriteObject(XmlDictionaryWriter, Object)	Writes the complete content (start, content, and end) of the object to the XML document or stream with the specified XmlDictionaryWriter. (Inherited from XmlObjectSerializer)
WriteObject(XmlDictionaryWriter, Object, DataContractResolver)	Writes all the object data (starting XML element, content, and enclosing element) to an XML document or stream using the specified XmlDictionaryWriter. The method includes a resolver for mapping xsi:type declarations at runtime.
WriteObject(XmlWriter, Object)	Writes all the object data (starting XML element, content, and closing element) to an XML document or stream with an XmlWriter.
WriteObjectContent(XmlDictionaryWriter, Object)	Writes the XML content using an XmlDictionaryWriter.
WriteObjectContent(XmlWriter, Object)	Writes the XML content using an XmlWriter.
WriteStartObject(XmlDictionaryWriter, Object)	Writes the opening XML element using an XmlDictionaryWriter.
WriteStartObject(XmlWriter, Object)	Writes the opening XML element using an XmlWriter.

Extension Methods

GetSerializationSurrogateProvider(DataContractSerializer)	Returns the surrogate serialization provider for this serializer.
SetSerializationSurrogateProvider(DataContractSerializer, ISerializationSurrogateProvider)	Specifies a surrogate serialization provider for this DataContractSerializer.

Thread Safety

Instances of this class are thread safe except when the instance is used with an implementation of the IDataContractSurrogate or DataContractResolver.

See also

• DataMemberAttribute
• DataContractAttribute
• IExtensibleDataObject
• ExtensionDataObject
• Using Data Contracts
• Serialization and Deserialization