XmlAttributes Constructor ()
Initializes a new instance of the XmlAttributes class.
Assembly: System.Xml (in System.Xml.dll)
The following example serializes an instance of a class named Orchestra, which contains a single field named Instruments that returns an array of Instrument objects. A second class named Brass inherits from the Instrument class. The example creates an XmlAttributes object to override the Instrument field--allowing the field to accept Brass objects--and adds the XmlAttributes object to an instance of the XmlAttributeOverrides class.
#using <System.Xml.dll> #using <System.dll> using namespace System; using namespace System::IO; using namespace System::Xml::Serialization; public ref class Instrument { public: String^ Name; }; public ref class Brass: public Instrument { public: bool IsValved; }; public ref class Orchestra { public: array<Instrument^>^Instruments; }; void SerializeObject( String^ filename ) { /* Each overridden field, property, or type requires an XmlAttributes object. */ XmlAttributes^ attrs = gcnew XmlAttributes; /* Create an XmlElementAttribute to override the field that returns Instrument objects. The overridden field returns Brass objects instead. */ XmlElementAttribute^ attr = gcnew XmlElementAttribute; attr->ElementName = "Brass"; attr->Type = Brass::typeid; // Add the element to the collection of elements. attrs->XmlElements->Add( attr ); // Create the XmlAttributeOverrides object. XmlAttributeOverrides^ attrOverrides = gcnew XmlAttributeOverrides; /* Add the type of the class that contains the overridden member and the XmlAttributes to override it with to the XmlAttributeOverrides object. */ attrOverrides->Add( Orchestra::typeid, "Instruments", attrs ); // Create the XmlSerializer using the XmlAttributeOverrides. XmlSerializer^ s = gcnew XmlSerializer( Orchestra::typeid,attrOverrides ); // Writing the file requires a TextWriter. TextWriter^ writer = gcnew StreamWriter( filename ); // Create the object that will be serialized. Orchestra^ band = gcnew Orchestra; // Create an object of the derived type. Brass^ i = gcnew Brass; i->Name = "Trumpet"; i->IsValved = true; array<Instrument^>^myInstruments = {i}; band->Instruments = myInstruments; // Serialize the object. s->Serialize( writer, band ); writer->Close(); } void DeserializeObject( String^ filename ) { XmlAttributeOverrides^ attrOverrides = gcnew XmlAttributeOverrides; XmlAttributes^ attrs = gcnew XmlAttributes; // Create an XmlElementAttribute to override the Instrument. XmlElementAttribute^ attr = gcnew XmlElementAttribute; attr->ElementName = "Brass"; attr->Type = Brass::typeid; // Add the element to the collection of elements. attrs->XmlElements->Add( attr ); attrOverrides->Add( Orchestra::typeid, "Instruments", attrs ); // Create the XmlSerializer using the XmlAttributeOverrides. XmlSerializer^ s = gcnew XmlSerializer( Orchestra::typeid,attrOverrides ); FileStream^ fs = gcnew FileStream( filename,FileMode::Open ); Orchestra^ band = dynamic_cast<Orchestra^>(s->Deserialize( fs )); Console::WriteLine( "Brass:" ); /* The difference between deserializing the overridden XML document and serializing it is this: To read the derived object values, you must declare an object of the derived type (Brass), and cast the Instrument instance to it. */ Brass^ b; System::Collections::IEnumerator^ myEnum = band->Instruments->GetEnumerator(); while ( myEnum->MoveNext() ) { Instrument^ i = safe_cast<Instrument^>(myEnum->Current); b = dynamic_cast<Brass^>(i); Console::WriteLine( "{0}\n{1}", b->Name, b->IsValved ); } } int main() { SerializeObject( "Override.xml" ); DeserializeObject( "Override.xml" ); }
Available since 8
.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