XmlArrayAttribute Class
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XmlArrayAttribute Class

 

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

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

System.Object
  System.Attribute
    System.Xml.Serialization.XmlArrayAttribute

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

NameDescription
System_CAPS_pubmethodXmlArrayAttribute()

Initializes a new instance of the XmlArrayAttribute class.

System_CAPS_pubmethodXmlArrayAttribute(String)

Initializes a new instance of the XmlArrayAttribute class and specifies the XML element name generated in the XML document instance.

NameDescription
System_CAPS_pubpropertyElementName

Gets or sets the XML element name given to the serialized array.

System_CAPS_pubpropertyForm

Gets or sets a value that indicates whether the XML element name generated by the XmlSerializer is qualified or unqualified.

System_CAPS_pubpropertyIsNullable

Gets 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.

System_CAPS_pubpropertyNamespace

Gets or sets the namespace of the XML element.

System_CAPS_pubpropertyOrder

Gets or sets the explicit order in which the elements are serialized or deserialized.

System_CAPS_pubpropertyTypeId

When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)

NameDescription
System_CAPS_pubmethodEquals(Object)

This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Returns the hash code for this instance.(Inherited from Attribute.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodIsDefaultAttribute()

When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)

System_CAPS_pubmethodMatch(Object)

When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

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.

System_CAPS_noteNote

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

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

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.

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;
}

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

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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