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XmlSerializer Constructor (Type, XmlAttributeOverrides, Type(), XmlRootAttribute, String)

Initializes a new instance of the XmlSerializer class that can serialize objects of type Object into XML document instances, and deserialize XML document instances into objects of type Object. Each object to be serialized can itself contain instances of classes, which this overload overrides with other classes. This overload also specifies the default namespace for all the XML elements and the class to use as the XML root element.

Namespace:  System.Xml.Serialization
Assembly:  System.Xml (in System.Xml.dll)

'Declaration
Public Sub New ( _
	type As Type, _
	overrides As XmlAttributeOverrides, _
	extraTypes As Type(), _
	root As XmlRootAttribute, _
	defaultNamespace As String _
)
'Usage
Dim type As Type 
Dim overrides As XmlAttributeOverrides 
Dim extraTypes As Type()
Dim root As XmlRootAttribute 
Dim defaultNamespace As String 

Dim instance As New XmlSerializer(type, overrides, _
	extraTypes, root, defaultNamespace)

Parameters

type
Type: System.Type

The type of the object that this XmlSerializer can serialize.

overrides
Type: System.Xml.Serialization.XmlAttributeOverrides

An XmlAttributeOverrides that extends or overrides the behavior of the class specified in the type parameter.

extraTypes
Type: System.Type()

A Type array of additional object types to serialize.

root
Type: System.Xml.Serialization.XmlRootAttribute

An XmlRootAttribute that defines the XML root element properties.

defaultNamespace
Type: System.String

The default namespace of all XML elements in the XML document.

The overrides parameter allows for the creation of an XmlSerializer that serializes a class that extends or overrides the behavior of a base class. For example, given a DLL, it is possible to create a class that inherits or extends a class contained in the DLL. To serialize such a class, you must use an instance of the XmlAttributeOverrides class when constructing the XmlSerializer. For more details, see XmlAttributeOverrides.

By default, if a public property or field returns an object, or array of objects, the object types are automatically serialized. However, if a class contains a field or property that returns an array of type Object, any object can be inserted into that array. In that case, the XmlSerializer must be instructed to expect all the possible object types that are inserted into the Object array. To do this, use the extraTypes parameter to specify the extra object types to serialize or deserialize.

The root element of an XML document encloses all the other elements. By default, the object specified by the type parameter is serialized as the root element. Properties, such as the XML element name of the root element are taken from the type object. However, the root parameter allows you to replace the default object's information by specifying an XmlRootAttribute; the object allows you to set a different namespace, element name, and so on.

Use the defaultName parameter to specify the default namespace of all XML elements generated by the XmlSerializer.

The following example serializes an instance of a class that is defined in a DLL and to do so, overrides the public members found in the class. The example also specifies an array of extra types, the default namespace for all XML elements, and the class to use that provides the XML root element information. The example assumes that the code at the beginning has been compiled into a DLL named HighSchool.

'Beginning of the HighSchool.dll  
Imports System
Imports System.IO
Imports System.Xml
Imports System.Xml.Serialization
Imports Microsoft.VisualBasic
' Imports HighSchool 

Namespace HighSchool

    Public Class Student
        Public Name As String 
        Public ID As Integer 
    End Class 'Student


    Public Class ClassRoom
        Public Students() As Student
    End Class 'ClassRoom
End Namespace 'HighSchool

Namespace College
    Public Class Graduate
        Inherits HighSchool.Student

        Public Sub New()
        End Sub 'New 
        ' Add a new field named University. 
        Public University As String 
        ' Use extra types to use this field. 
        Public Info() As Object
    End Class 'Graduate


    Public Class Address
        Public City As String 
    End Class 'Address


    Public Class Phone
        Public Number As String 
    End Class 'Phone


    Public Class Run

        Public Shared Sub Main()
            Dim test As New Run()
            test.WriteOverriddenAttributes("College.xml")
            test.ReadOverriddenAttributes("College.xml")
        End Sub 'Main


        Private Sub WriteOverriddenAttributes(ByVal filename As String)
            ' Writing the file requires a TextWriter. 
            Dim myStreamWriter As New StreamWriter(filename)
            ' Create an XMLAttributeOverrides class. 
            Dim attrOverrides As New XmlAttributeOverrides()
            ' Create the XmlAttributes class. 
            Dim attrs As New XmlAttributes()
            ' Override the Student class. "Alumni" is the name 
            ' of the overriding element in the XML output.  

            Dim attr As New XmlElementAttribute("Alumni", GetType(Graduate))
            ' Add the XmlElementAttribute to the collection of 
            ' elements in the XmlAttributes object. 
            attrs.XmlElements.Add(attr)
            ' Add the XmlAttributes to the XmlAttributeOverrides. 
            ' "Students" is the name being overridden. 
            attrOverrides.Add(GetType(HighSchool.ClassRoom), "Students", attrs)

            ' Create array of extra types. 
            Dim extraTypes(1) As Type
            extraTypes(0) = GetType(Address)
            extraTypes(1) = GetType(Phone)

            ' Create an XmlRootAttribute. 
            Dim root As New XmlRootAttribute("Graduates")

            ' Create the XmlSerializer with the 
            ' XmlAttributeOverrides object.  
            Dim mySerializer As New XmlSerializer(GetType(HighSchool.ClassRoom), _
                attrOverrides, extraTypes, root, "http://www.microsoft.com")

            Dim oMyClass As New HighSchool.ClassRoom()

            Dim g1 As New Graduate()
            g1.Name = "Jacki"
            g1.ID = 1
            g1.University = "Alma" 

            Dim g2 As New Graduate()
            g2.Name = "Megan"
            g2.ID = 2
            g2.University = "CM" 

            Dim myArray As HighSchool.Student() = {g1, g2}

            oMyClass.Students = myArray

            ' Create extra information. 
            Dim a1 As New Address()
            a1.City = "Ionia" 
            Dim a2 As New Address()
            a2.City = "Stamford" 
            Dim p1 As New Phone()
            p1.Number = "555-0101" 
            Dim p2 As New Phone()
            p2.Number = "555-0100" 

            Dim o1() As Object = {a1, p1}
            Dim o2() As Object = {a2, p2}

            g1.Info = o1
            g2.Info = o2
            mySerializer.Serialize(myStreamWriter, oMyClass)
            myStreamWriter.Close()
        End Sub 'WriteOverriddenAttributes


        Private Sub ReadOverriddenAttributes(ByVal filename As String)
            ' The majority of the code here is the same as that in the 
            ' WriteOverriddenAttributes method. Because the XML being read 
            ' doesn't conform to the schema defined by the DLL, the 
            ' XMLAttributesOverrides must be used to create an 
            ' XmlSerializer instance to read the XML document. 

            Dim attrOverrides As New XmlAttributeOverrides()
            Dim attrs As New XmlAttributes()
            Dim attr As New XmlElementAttribute("Alumni", GetType(Graduate))
            attrs.XmlElements.Add(attr)
            attrOverrides.Add(GetType(HighSchool.ClassRoom), "Students", attrs)

            Dim extraTypes(1) As Type
            extraTypes(0) = GetType(Address)
            extraTypes(1) = GetType(Phone)

            Dim root As New XmlRootAttribute("Graduates")

            Dim readSerializer As New XmlSerializer(GetType(HighSchool.ClassRoom), _
                attrOverrides, extraTypes, root, "http://www.microsoft.com")

            ' A FileStream object is required to read the file.  
            Dim fs As New FileStream(filename, FileMode.Open)

            Dim oMyClass As HighSchool.ClassRoom
            oMyClass = CType(readSerializer.Deserialize(fs), HighSchool.ClassRoom)

            ' Here is the difference between reading and writing an 
            ' XML document: You must declare an object of the derived 
            ' type (Graduate) and cast the Student instance to it. 
            Dim g As Graduate
            Dim a As Address
            Dim p As Phone
            Dim grad As Graduate
            For Each grad In oMyClass.Students
                g = CType(grad, Graduate)
                Console.Write((g.Name & ControlChars.Tab))
                Console.Write((g.ID & ControlChars.Tab))
                Console.Write((g.University & ControlChars.Cr))
                a = CType(g.Info(0), Address)
                Console.WriteLine(a.City)
                p = CType(g.Info(1), Phone)
                Console.WriteLine(p.Number)
            Next grad
        End Sub 'ReadOverriddenAttributes
    End Class 'Run
End Namespace 'College
// Beginning of the HighSchool.dll 
#using <mscorlib.dll>
#using <System.Xml.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml;
using namespace System::Xml::Serialization; 

namespace HighSchool
{
   public __gc class Student
   {
   public:
      String* Name;
      int ID;
   };

   public __gc class MyClass
   {
   public:
      Student* Students[];
   };
}

namespace College
{
   using namespace HighSchool;
public __gc class Graduate: public HighSchool::Student
{
public:
   Graduate(){}
   // Add a new field named University.
   String* University;
   // Use extra types to use this field.
   Object* Info[];
};

public __gc class Address
{
public:
   String* City;
};

public __gc class Phone
{
public:
   String* Number;
};

public __gc class Run
{
public:
   static void main()
   {
      Run* test = new Run();
      test->WriteOverriddenAttributes(S"College.xml");
      test->ReadOverriddenAttributes(S"College.xml");
   }

private:
   void WriteOverriddenAttributes(String* filename)
   {
      // Writing the file requires a TextWriter.
      TextWriter* myStreamWriter = new StreamWriter(filename);
      // Create an XMLAttributeOverrides class.
      XmlAttributeOverrides* attrOverrides = 
         new XmlAttributeOverrides();
      // Create the XmlAttributes class.
      XmlAttributes* attrs = new XmlAttributes();
      /* Override the Student class. "Alumni" is the name
      of the overriding element in the XML output. */

      XmlElementAttribute* attr = 
         new XmlElementAttribute(S"Alumni", __typeof(Graduate));
      /* Add the XmlElementAttribute to the collection of
      elements in the XmlAttributes object. */
      attrs->XmlElements->Add(attr);
      /* Add the XmlAttributes to the XmlAttributeOverrides. 
      "Students" is the name being overridden. */
      attrOverrides->Add(__typeof(HighSchool::MyClass), 
         S"Students", attrs);

      // Create array of extra types.
      Type* extraTypes[] = new Type*[2];
      extraTypes[0]=__typeof(Address);
      extraTypes[1]=__typeof(Phone);

      // Create an XmlRootAttribute.
      XmlRootAttribute* root = new XmlRootAttribute(S"Graduates");

      /* Create the XmlSerializer with the 
      XmlAttributeOverrides object. */
      XmlSerializer* mySerializer = new XmlSerializer
         (__typeof(HighSchool::MyClass), attrOverrides, extraTypes,
         root, S"http://www.microsoft.com");

      MyClass* myClass= new MyClass();

      Graduate* g1 = new Graduate();
      g1->Name = S"Jacki";
      g1->ID = 1;
      g1->University = S"Alma";

      Graduate* g2 = new Graduate();
      g2->Name = S"Megan";
      g2->ID = 2;
      g2->University = S"CM";

      Student* myArray[] = {g1,g2};

      myClass->Students = myArray;

      // Create extra information.
      Address* a1 = new Address();
      a1->City = S"Ionia";
      Address* a2 = new Address();
      a2->City = S"Stamford";
      Phone* p1 = new Phone();
      p1->Number = S"555-0101";
      Phone* p2 = new Phone();
      p2->Number = S"555-0100";

      Object* o1[] = {a1, p1};
      Object* o2[] = {a2,p2};

      g1->Info = o1;
      g2->Info = o2;
      mySerializer->Serialize(myStreamWriter,myClass);
      myStreamWriter->Close();
   }

private:
   void ReadOverriddenAttributes(String* filename)
   {
      /* The majority of the code here is the same as that in the
      WriteOverriddenAttributes method. Because the XML being read
      doesn't conform to the schema defined by the DLL, the
      XMLAttributesOverrides must be used to create an 
      XmlSerializer instance to read the XML document.*/

      XmlAttributeOverrides* attrOverrides = new 
         XmlAttributeOverrides();
      XmlAttributes* attrs = new XmlAttributes();
      XmlElementAttribute* attr = 
         new XmlElementAttribute(S"Alumni", __typeof(Graduate));
      attrs->XmlElements->Add(attr);
      attrOverrides->Add(__typeof(HighSchool::MyClass), 
         S"Students", attrs);

      Type* extraTypes[] = new Type*[2];
      extraTypes[0] = __typeof(Address);
      extraTypes[1] = __typeof(Phone);

      XmlRootAttribute* root = new XmlRootAttribute(S"Graduates");

      XmlSerializer* readSerializer = new XmlSerializer
         (__typeof(HighSchool::MyClass), attrOverrides, extraTypes,
         root, S"http://www.microsoft.com");

      // A FileStream object is required to read the file. 
      FileStream* fs = new FileStream(filename, FileMode::Open);

      MyClass* myClass;
      myClass = dynamic_cast<MyClass*> (readSerializer->Deserialize(fs));

      /* Here is the difference between reading and writing an 
      XML document: You must declare an object of the derived 
      type (Graduate) and cast the Student instance to it.*/
      Graduate* g;
      Address* a;
      Phone* p;
      System::Collections::IEnumerator* myEnum = myClass->Students->GetEnumerator();
      while (myEnum->MoveNext())
      {
         Graduate* grad = __try_cast<Graduate*>(myEnum->Current);
         g = dynamic_cast<Graduate*> (grad);
         Console::Write(S"{0}\t", g->Name);
         Console::Write(S"{0}\t", __box(g->ID));
         Console::Write(S"{0}\n", g->University);
         a = dynamic_cast<Address*> (g->Info[0]);
         Console::WriteLine(a->City);
         p = dynamic_cast<Phone*> (g->Info[1]);
         Console::WriteLine(p->Number);
      }
   }
};
}
int main()
{
   College::Run::main();
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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