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XmlArrayItemAttribute Class

Represents an attribute that specifies the derived types that the XmlSerializer can place in a serialized array.

System.Object
  System.Attribute
    System.Xml.Serialization.XmlArrayItemAttribute

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

[AttributeUsageAttribute(AttributeTargets.Property|AttributeTargets.Field|AttributeTargets.Parameter|AttributeTargets.ReturnValue, AllowMultiple = true)]
public class XmlArrayItemAttribute : Attribute

The XmlArrayItemAttribute type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsXmlArrayItemAttribute()Initializes a new instance of the XmlArrayItemAttribute class.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsXmlArrayItemAttribute(String)Initializes a new instance of the XmlArrayItemAttribute class and specifies the name of the XML element generated in the XML document.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsXmlArrayItemAttribute(Type)Initializes a new instance of the XmlArrayItemAttribute class and specifies the Type that can be inserted into the serialized array.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsXmlArrayItemAttribute(String, Type)Initializes a new instance of the XmlArrayItemAttribute class and specifies the name of the XML element generated in the XML document and the Type that can be inserted into the generated XML document.
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  NameDescription
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsDataTypeGets or sets the XML data type of the generated XML element.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsElementNameGets or sets the name of the generated XML element.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsFormGets or sets a value that indicates whether the name of the generated XML element is qualified.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsNullableGets 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 propertySupported by the XNA FrameworkIsNullableSpecifiedGets whether the xsi:nil attribute has been set to true.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsNamespaceGets or sets the namespace of the generated XML element.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsNestingLevelGets or sets the level in a hierarchy of XML elements that the XmlArrayItemAttribute affects.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsTypeGets or sets the type allowed in an array.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodSupported by the XNA FrameworkMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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The XmlArrayItemAttribute 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 XmlArrayItemAttribute to any public read/write member that returns an array, or provides access to one. For example, a field that returns an array of objects, a collection, an ArrayList, or any class that implements the IEnumerable interface.

The XmlArrayItemAttribute supports polymorphism--in other words, it allows the XmlSerializer to add derived objects to an array. For example, suppose a class named Mammal is derived from a base class named Animal. Further suppose that a class named MyAnimals contains a field that returns an array of Animal objects. To allow the XmlSerializer to serialize both the Animal and Mammal type, apply the XmlArrayItemAttribute to the field twice, each time specifying one of the two acceptable types.

NoteNote

You can apply multiple instances of the XmlArrayItemAttribute or XmlElementAttribute to specify types of objects that can be inserted into the array.

NoteNote

The serialization of a field or property that returns an interface or array of interfaces is not supported.

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

NoteNote

You can use the word XmlArrayItem in your code instead of the longer XmlArrayItemAttribute.

The following example serializes a class named Group that contains a field named Employees that returns an array of Employee objects. The example applies the XmlArrayItemAttribute to the field, thereby instructing the XmlSerializer that it can insert objects of both the base class (Employee) type and derived class type (Manager) into the serialized array.

using System;
using System.IO;
using System.Xml.Serialization;

public class Group
{  
   /* The XmlArrayItemAttribute allows the XmlSerializer to insert
      both the base type (Employee) and derived type (Manager) 
      into serialized arrays. */

   [XmlArrayItem(typeof(Manager)),
   XmlArrayItem(typeof(Employee))]
   public Employee[] Employees;

   /* Use the XmlArrayItemAttribute to specify types allowed
      in an array of Object items. */
   [XmlArray]
   [XmlArrayItem (typeof(int),
   ElementName = "MyNumber"),
   XmlArrayItem (typeof(string),
   ElementName = "MyString"),
   XmlArrayItem(typeof(Manager))]
   public object [] ExtraInfo;
}   

public class Employee
{
   public string Name;
}

public class Manager:Employee{
   public int Level;
}

public class Run
{
   public static void Main()
   {
      Run test = new Run();
      test.SerializeObject("TypeDoc.xml");
      test.DeserializeObject("TypeDoc.xml");
   }


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

      // Writing the XML file to disk requires a TextWriter.
      TextWriter writer = new StreamWriter(filename);
      Group group = new Group();

      Manager manager = new Manager();
      Employee emp1 = new Employee();
      Employee emp2 = new Employee();
      manager.Name = "Consuela";
      manager.Level = 3;
      emp1.Name = "Seiko";
      emp2.Name = "Martina";
      Employee [] emps = new Employee[3]{manager, emp1, emp2};
      group.Employees = emps;

      // Creates an int and a string and assigns to ExtraInfo. 
      group.ExtraInfo = new Object[3]{43, "Extra", manager};

      // Serializes the object, and closes the StreamWriter.
      s.Serialize(writer, group);
      writer.Close();
   }

   public void DeserializeObject(string filename)
   {
      FileStream fs = new FileStream(filename, FileMode.Open);
      XmlSerializer x = new XmlSerializer(typeof(Group));
      Group g = (Group) x.Deserialize(fs);
      Console.WriteLine("Members:");

      foreach(Employee e in g.Employees) 
      {
         Console.WriteLine("\t" + e.Name);
      }
   }
}
   

.NET Framework

Supported in: 4.5, 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

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

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.

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