.NET Framework Class Library
XmlArrayAttribute Class

Specifies that the XmlSerializer must serialize a particular class member as an array of XML elements.

Inheritance Hierarchy
SystemObject
   SystemAttribute
    System.Xml.SerializationXmlArrayAttribute

Namespace:   System.Xml.Serialization
Assemblies:   System.Xml.XmlSerializer (in System.Xml.XmlSerializer.dll)
  System.Xml (in System.Xml.dll)
Syntax
<[%$TOPIC/t67f0789_en-us_VS_110_3_0_0_0_0%]([%$TOPIC/t67f0789_en-us_VS_110_3_0_0_0_1%].Property Or [%$TOPIC/t67f0789_en-us_VS_110_3_0_0_0_2%].Field Or [%$TOPIC/t67f0789_en-us_VS_110_3_0_0_0_3%].Parameter Or [%$TOPIC/t67f0789_en-us_VS_110_3_0_0_0_4%].ReturnValue, AllowMultiple := False)> _
Public Class XmlArrayAttribute _
	Inherits [%$TOPIC/t67f0789_en-us_VS_110_3_0_0_0_5%]
[[%$TOPIC/t67f0789_en-us_VS_110_3_0_1_0_0%]([%$TOPIC/t67f0789_en-us_VS_110_3_0_1_0_1%].Property|[%$TOPIC/t67f0789_en-us_VS_110_3_0_1_0_2%].Field|[%$TOPIC/t67f0789_en-us_VS_110_3_0_1_0_3%].Parameter|[%$TOPIC/t67f0789_en-us_VS_110_3_0_1_0_4%].ReturnValue, AllowMultiple = false)]
public class XmlArrayAttribute : [%$TOPIC/t67f0789_en-us_VS_110_3_0_1_0_5%]
[[%$TOPIC/t67f0789_en-us_VS_110_3_0_2_0_0%]([%$TOPIC/t67f0789_en-us_VS_110_3_0_2_0_1%]::Property|[%$TOPIC/t67f0789_en-us_VS_110_3_0_2_0_2%]::Field|[%$TOPIC/t67f0789_en-us_VS_110_3_0_2_0_3%]::Parameter|[%$TOPIC/t67f0789_en-us_VS_110_3_0_2_0_4%]::ReturnValue, AllowMultiple = false)]
public ref class XmlArrayAttribute : public [%$TOPIC/t67f0789_en-us_VS_110_3_0_2_0_5%]
[<[%$TOPIC/t67f0789_en-us_VS_110_3_0_3_0_0%]([%$TOPIC/t67f0789_en-us_VS_110_3_0_3_0_1%].Property|[%$TOPIC/t67f0789_en-us_VS_110_3_0_3_0_2%].Field|[%$TOPIC/t67f0789_en-us_VS_110_3_0_3_0_3%].Parameter|[%$TOPIC/t67f0789_en-us_VS_110_3_0_3_0_4%].ReturnValue, AllowMultiple = false)>]
type XmlArrayAttribute =  
    class 
        inherit [%$TOPIC/t67f0789_en-us_VS_110_3_0_3_0_5%] 
    end

The XmlArrayAttribute type exposes the following members.

Constructors
  NameDescription
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps XmlArrayAttributeInitializes a new instance of the XmlArrayAttribute class.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps XmlArrayAttribute(String)Initializes a new instance of the XmlArrayAttribute class and specifies the XML element name generated in the XML document instance.
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Properties
  NameDescription
Public property Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps ElementNameGets or sets the XML element name given to the serialized array.
Public property Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps FormGets or sets a value that indicates whether the XML element name generated by the XmlSerializer is qualified or unqualified.
Public property Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps IsNullableGets or sets a value that indicates whether the XmlSerializer must serialize a member as an empty XML tag with the xsi:nil attribute set to true.
Public property Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps NamespaceGets or sets the namespace of the XML element.
Public property Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps OrderGets or sets the explicit order in which the elements are serialized or deserialized.
Public property TypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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Methods
  NameDescription
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps EqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Protected method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps FinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps GetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps GetTypeGets the Type of the current instance. (Inherited from Object.)
Public method IsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public method Supported by the XNA Framework MatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps MemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps ToStringReturns a string that represents the current object. (Inherited from Object.)
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Explicit Interface Implementations
  NameDescription
Explicit interface implemetation Private method _AttributeGetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeGetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeGetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeInvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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Remarks

The XmlArrayAttribute belongs to a family of attributes that controls how the XmlSerializer serializes or deserializes an object. For a complete list of similar attributes, see Attributes That Control XML Serialization.

You can apply the XmlArrayAttribute to a public field or read/write property that returns an array of objects. You can also apply it to collections and fields that return an ArrayList or any field that returns an object that implements the IEnumerable interface.

When you apply the XmlArrayAttribute to a class member, the Serialize method of the XmlSerializer class generates a nested sequence of XML elements from that member. An XML schema document (an .xsd file), indicates such an array as a complexType. For example, if the class to be serialized represents a purchase order, you can generate an array of purchased items by applying the XmlArrayAttribute to a public field that returns an array of objects that represent order items.

If no attributes are applied to a public field or property that returns an array of complex or primitive type objects, the XmlSerializer generates a nested sequence of XML elements by default. To more precisely control what XML elements are generated, apply an XmlArrayItemAttribute and an XmlArrayAttribute to the field or property. For example, by default, the name of the generated XML element is derived from the member identifier You can change the name of the generated XML element by setting the ElementName property.

If you serialize an array that contains items of a specific type and all the classes derived from that type, you must use the XmlArrayItemAttribute to declare each of the types.

NoteNote

You can use XmlArray in your code instead of the longer XmlArrayAttribute.

For more information about using attributes, see Extending Metadata Using Attributes.

Examples

The following example serializes a class instance into an XML document that contains several object arrays. The XmlArrayAttribute is applied to the members that become XML element arrays.

Option Explicit
Option Strict

Imports System
Imports System.IO
Imports System.Xml.Serialization
Imports System.Xml


Public Class Run

    Public Shared Sub Main()
        Dim test As New Run()
        test.SerializeDocument("books.xml")
    End Sub 


    Public Sub SerializeDocument(ByVal filename As String)
        ' Creates a new XmlSerializer. 
        Dim s As New XmlSerializer(GetType(MyRootClass))

        ' Writing the file requires a StreamWriter. 
        Dim myWriter As New StreamWriter(filename)

        ' Creates an instance of the class to serialize.  
        Dim myRootClass As New MyRootClass()

        ' Uses a basic method of creating an XML array: Create and 
        ' populate a string array, and assign it to the 
        ' MyStringArray property.  

        Dim myString() As String =  {"Hello", "world", "!"}
        myRootClass.MyStringArray = myString

        ' Uses a more advanced method of creating an array: 
        ' create instances of the Item and BookItem, where BookItem 
        ' is derived from Item.  
        Dim item1 As New Item()
        Dim item2 As New BookItem()

        ' Sets the objects' properties. 
        With item1
            .ItemName = "Widget1"
            .ItemCode = "w1"
            .ItemPrice = 231
            .ItemQuantity = 3
        End With 

        With item2
            .ItemCode = "w2"
            .ItemPrice = 123
            .ItemQuantity = 7
            .ISBN = "34982333"
            .Title = "Book of Widgets"
            .Author = "John Smith" 
        End With 

        ' Fills the array with the items. 
        Dim myItems() As Item =  {item1, item2}

        ' Set class's Items property to the array.
        myRootClass.Items = myItems

        ' Serializes the class, writes it to disk, and closes 
        ' the TextWriter. 
        s.Serialize(myWriter, myRootClass)
        myWriter.Close()
    End Sub 
End Class 


' This is the class that will be serialized. 
Public Class MyRootClass
    Private myItems() As Item

    ' Here is a simple way to serialize the array as XML. Using the 
    ' XmlArrayAttribute, assign an element name and namespace. The 
    ' IsNullable property determines whether the element will be 
    ' generated if the field is set to a null value. If set to true, 
    ' the default, setting it to a null value will cause the XML 
    ' xsi:null attribute to be generated.
    <XmlArray(ElementName := "MyStrings", _
         Namespace := "http://www.cpandl.com", _
         IsNullable := True)> _
    Public MyStringArray() As String 

    ' Here is a more complex example of applying an 
    ' XmlArrayAttribute. The Items property can contain both Item 
    ' and BookItem objects. Use the XmlArrayItemAttribute to specify 
    ' that both types can be inserted into the array.
    <XmlArrayItem(ElementName := "Item", _
        IsNullable := True, _
        Type := GetType(Item), _
        Namespace := "http://www.cpandl.com"), _
     XmlArrayItem(ElementName := "BookItem", _
        IsNullable := True, _
        Type := GetType(BookItem), _
        Namespace := "http://www.cohowinery.com"), _
     XmlArray()> _
    Public Property Items As Item()
        Get 
            Return myItems
        End Get 
        Set
            myItems = value
        End Set 
    End Property 
End Class 

Public Class Item
    <XmlElement(ElementName := "OrderItem")> _
    Public ItemName As String 
    Public ItemCode As String 
    Public ItemPrice As Decimal 
    Public ItemQuantity As Integer 
End Class 

Public Class BookItem
    Inherits Item
    Public Title As String 
    Public Author As String 
    Public ISBN As String 
End Class
using System;
using System.IO;
using System.Xml.Serialization;
using System.Xml;

public class Run
{
   public static void Main()
   {
      Run test = new Run();
      test.SerializeDocument("books.xml");
   }

   public void SerializeDocument(string filename)
   {
      // Creates a new XmlSerializer.
      XmlSerializer s = 
      new XmlSerializer(typeof(MyRootClass));

      // Writing the file requires a StreamWriter.
      TextWriter myWriter= new StreamWriter(filename);

      // Creates an instance of the class to serialize. 
      MyRootClass myRootClass = new MyRootClass();

      /* Uses a basic method of creating an XML array: Create and 
      populate a string array, and assign it to the 
      MyStringArray property. */ 

      string [] myString = {"Hello", "world", "!"};
      myRootClass.MyStringArray = myString;

      /* Uses a more advanced method of creating an array:
         create instances of the Item and BookItem, where BookItem 
         is derived from Item. */
      Item item1 = new Item();
      BookItem item2 = new BookItem();

      // Sets the objects' properties.
      item1.ItemName = "Widget1";
      item1.ItemCode = "w1";
      item1.ItemPrice = 231;
      item1.ItemQuantity = 3;

      item2.ItemCode = "w2";
      item2.ItemPrice = 123;
      item2.ItemQuantity = 7;
      item2.ISBN = "34982333";
      item2.Title = "Book of Widgets";
      item2.Author = "John Smith";

      // Fills the array with the items.
      Item [] myItems = {item1,item2};

      // Sets the class's Items property to the array.
      myRootClass.Items = myItems;

      /* Serializes the class, writes it to disk, and closes 
         the TextWriter. */
      s.Serialize(myWriter, myRootClass);
      myWriter.Close();
   }
}

// This is the class that will be serialized. 
public class MyRootClass
{
   private Item [] items;

   /* Here is a simple way to serialize the array as XML. Using the
      XmlArrayAttribute, assign an element name and namespace. The
      IsNullable property determines whether the element will be 
      generated if the field is set to a null value. If set to true,
      the default, setting it to a null value will cause the XML
      xsi:null attribute to be generated. */
   [XmlArray(ElementName = "MyStrings",
   Namespace = "http://www.cpandl.com", IsNullable = true)]
   public string[] MyStringArray;

   /* Here is a more complex example of applying an 
      XmlArrayAttribute. The Items property can contain both Item 
      and BookItem objects. Use the XmlArrayItemAttribute to specify
      that both types can be inserted into the array. */
   [XmlArrayItem(ElementName= "Item", 
   IsNullable=true,
   Type = typeof(Item),
   Namespace = "http://www.cpandl.com"),
   XmlArrayItem(ElementName = "BookItem", 
   IsNullable = true, 
   Type = typeof(BookItem),
   Namespace = "http://www.cohowinery.com")]
   [XmlArray]
   public Item []Items
   {
      get{return items;}
      set{items = value;}
   }
}

public class Item{
   [XmlElement(ElementName = "OrderItem")]
   public string ItemName;
   public string ItemCode;
   public decimal ItemPrice;
   public int ItemQuantity;
}

public class BookItem:Item
{
   public string Title;
   public string Author;
   public string ISBN;
}
   
#using <System.Xml.dll>
#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;
using namespace System::Xml;
public ref class Item
{
public:

   [XmlElement(ElementName="OrderItem")]
   String^ ItemName;
   String^ ItemCode;
   Decimal ItemPrice;
   int ItemQuantity;
};

public ref class BookItem: public Item
{
public:
   String^ Title;
   String^ Author;
   String^ ISBN;
};

// This is the class that will be serialized. 
public ref class MyRootClass
{
private:
   array<Item^>^items;

public:

   /* Here is a simple way to serialize the array as XML. Using the
         XmlArrayAttribute, assign an element name and namespace. The
         IsNullable property determines whether the element will be 
         generated if the field is set to a null value. If set to true,
         the default, setting it to a null value will cause the XML
         xsi:null attribute to be generated. */

   [XmlArray(ElementName="MyStrings",
   Namespace="http://www.cpandl.com",IsNullable=true)]
   array<String^>^MyStringArray;

   /* Here is a more complex example of applying an 
         XmlArrayAttribute. The Items property can contain both Item 
         and BookItem objects. Use the XmlArrayItemAttribute to specify
         that both types can be inserted into the array. */
   [XmlArrayItem(ElementName="Item",
   IsNullable=true,
   Type=Item::typeid,
   Namespace="http://www.cpandl.com"),
   XmlArrayItem(ElementName="BookItem",
   IsNullable=true,
   Type=BookItem::typeid,
   Namespace="http://www.cohowinery.com")]
   [XmlArray]
   property array<Item^>^ Items 
   {
      array<Item^>^ get()
      {
         return items;
      }

      void set( array<Item^>^value )
      {
         items = value;
      }
   }
};

public ref class Run
{
public:
   void SerializeDocument( String^ filename )
   {
      // Creates a new XmlSerializer.
      XmlSerializer^ s = gcnew XmlSerializer( MyRootClass::typeid );

      // Writing the file requires a StreamWriter.
      TextWriter^ myWriter = gcnew StreamWriter( filename );

      // Creates an instance of the class to serialize. 
      MyRootClass^ myRootClass = gcnew MyRootClass;

      /* Uses a basic method of creating an XML array: Create and 
            populate a string array, and assign it to the 
            MyStringArray property. */ 
      array<String^>^myString = {"Hello","world","!"};
      myRootClass->MyStringArray = myString;

      /* Uses a more advanced method of creating an array:
               create instances of the Item and BookItem, where BookItem 
               is derived from Item. */
      Item^ item1 = gcnew Item;
      BookItem^ item2 = gcnew BookItem;

      // Sets the objects' properties.
      item1->ItemName = "Widget1";
      item1->ItemCode = "w1";
      item1->ItemPrice = 231;
      item1->ItemQuantity = 3;
      item2->ItemCode = "w2";
      item2->ItemPrice = 123;
      item2->ItemQuantity = 7;
      item2->ISBN = "34982333";
      item2->Title = "Book of Widgets";
      item2->Author = "John Smith";

      // Fills the array with the items. 
      array<Item^>^myItems = {item1,item2};

      // Sets the class's Items property to the array.
      myRootClass->Items = myItems;

      /* Serializes the class, writes it to disk, and closes 
               the TextWriter. */
      s->Serialize( myWriter, myRootClass );
      myWriter->Close();
   }
};

int main()
{
   Run^ test = gcnew Run;
   test->SerializeDocument( "books.xml" );
}
Version Information

.NET Framework

Supported in: 4.5.3, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
Platforms

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.