SoapAttributes.SoapDefaultValue Property

Reference

Definition

Namespace:: System.Xml.Serialization

Assembly:: System.Xml.XmlSerializer.dll

Assembly:: System.Xml.dll

Assembly:: netstandard.dll

Source:: SoapAttributes.cs

Source:: SoapAttributes.cs

Source:: SoapAttributes.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Gets or sets the default value of an XML element or attribute.

public:
 property System::Object ^ SoapDefaultValue { System::Object ^ get(); void set(System::Object ^ value); };

public object? SoapDefaultValue { get; set; }

public object SoapDefaultValue { get; set; }

member this.SoapDefaultValue : obj with get, set

Public Property SoapDefaultValue As Object

Property Value

Object

An object that represents the default value of an XML element or attribute.

Examples

The following example serializes a class named Group that includes a field named GroupName. The default value is set with the DefaultValueAttribute to ".NET". By either not setting the field, or by setting it to ".NET", the value is not serialized (because the default value is already known). The sample also overrides the default value in the CreateOverrideSerializer method, which is called by the SerializeOverride method. The example calls both methods, SerializeOriginal and SerializeOverride, and sets the same value (".NET") for the GroupName field. Because of the override, the value is serialized only when calling the SerializeOverride method.

#using <System.dll>
#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
using namespace System::Xml::Serialization;
using namespace System::Xml::Schema;
using namespace System::ComponentModel;
public ref class Group
{
public:

   // The default is set to .NET.

   [DefaultValue(".NET")]
   String^ GroupName;
};

public ref class Run
{
public:
   void SerializeOriginal( String^ filename )
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer^ mySerializer = gcnew XmlSerializer( Group::typeid );

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

      // Create an instance of the class that will be serialized.
      Group^ myGroup = gcnew Group;

      // Setting the GroupName to '.NET' is like not setting it at all
      // because it is the default value. So no value will be 
      // serialized, and on deserialization it will appear as a blank.
      myGroup->GroupName = ".NET";

      // Serialize the class, and close the TextWriter.
      mySerializer->Serialize( writer, myGroup );
      writer->Close();
   }

   void SerializeOverride( String^ filename )
   {
      // Create an instance of the XmlSerializer class
      // that overrides the serialization.
      XmlSerializer^ overRideSerializer = CreateOverrideSerializer();

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

      // Create an instance of the class that will be serialized.
      Group^ myGroup = gcnew Group;

      // The  specifies that the default value is now 
      // 'Team1'. So setting the GroupName to '.NET' means
      // the value will be serialized.
      myGroup->GroupName = ".NET";

      // Serialize the class, and close the TextWriter.
      overRideSerializer->Serialize( writer, myGroup );
      writer->Close();
   }

   void DeserializeOriginal( String^ filename )
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer^ mySerializer = gcnew XmlSerializer( Group::typeid );

      // Reading the file requires a TextReader.
      TextReader^ reader = gcnew StreamReader( filename );

      // Deserialize and cast the Object*.
      Group^ myGroup;
      myGroup = safe_cast<Group^>(mySerializer->Deserialize( reader ));
      Console::WriteLine( myGroup->GroupName );
      Console::WriteLine();
   }

   void DeserializeOverride( String^ filename )
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer^ overRideSerializer = CreateOverrideSerializer();

      // Reading the file requires a TextReader.
      TextReader^ reader = gcnew StreamReader( filename );

      // Deserialize and cast the Object*.
      Group^ myGroup;
      myGroup = safe_cast<Group^>(overRideSerializer->Deserialize( reader ));
      Console::WriteLine( myGroup->GroupName );
   }

private:
   XmlSerializer^ CreateOverrideSerializer()
   {
      SoapAttributeOverrides^ mySoapAttributeOverrides = gcnew SoapAttributeOverrides;
      SoapAttributes^ soapAtts = gcnew SoapAttributes;

      // Create a new DefaultValueAttribute Object* for the GroupName
      // property.
      DefaultValueAttribute^ newDefault = gcnew DefaultValueAttribute( "Team1" );
      soapAtts->SoapDefaultValue = newDefault;
      mySoapAttributeOverrides->Add( Group::typeid, "GroupName", soapAtts );

      // Create an XmlTypeMapping that is used to create an instance 
      // of the XmlSerializer. Then return the XmlSerializer Object*.
      XmlTypeMapping^ myMapping = (gcnew SoapReflectionImporter( mySoapAttributeOverrides ))->ImportTypeMapping( Group::typeid );
      XmlSerializer^ ser = gcnew XmlSerializer( myMapping );
      return ser;
   }
};

int main()
{
   Run^ test = gcnew Run;
   test->SerializeOriginal( "SoapOriginal.xml" );
   test->SerializeOverride( "mySoapAttributeOverridesideAttributes.xml" );
   test->DeserializeOriginal( "SoapOriginal.xml" );
   test->DeserializeOverride( "mySoapAttributeOverridesideAttributes.xml" );
}

using System;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
using System.Xml.Schema;
using System.ComponentModel;

public class Group
{
   // The default is set to .NET.
   [DefaultValue(".NET")]
   public string GroupName;
}

public class Run
{
   public static void Main()
   {
      Run test = new Run();
      test.SerializeOriginal("SoapOriginal.xml");
      test.SerializeOverride("mySoapAttributeOverridesideAttributes.xml");
      test.DeserializeOriginal("SoapOriginal.xml");
      test.DeserializeOverride("mySoapAttributeOverridesideAttributes.xml");
   }
   public void SerializeOriginal(string filename)
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer mySerializer =
      new XmlSerializer(typeof(Group));

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

      // Create an instance of the class that will be serialized.
      Group myGroup = new Group();

      // Setting the GroupName to '.NET' is like not setting it at all
      // because it is the default value. So no value will be
      // serialized, and on deserialization it will appear as a blank.
      myGroup.GroupName = ".NET";

      // Serialize the class, and close the TextWriter.
      mySerializer.Serialize(writer, myGroup);
      writer.Close();
   }

   public void SerializeOverride(string filename)
   {
      // Create an instance of the XmlSerializer class
      // that overrides the serialization.
      XmlSerializer overRideSerializer = CreateOverrideSerializer();

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

      // Create an instance of the class that will be serialized.
      Group myGroup = new Group();

      // The override specifies that the default value is now
      // 'Team1'. So setting the GroupName to '.NET' means
      // the value will be serialized.
      myGroup.GroupName = ".NET";
      // Serialize the class, and close the TextWriter.
      overRideSerializer.Serialize(writer, myGroup);
       writer.Close();
   }

   public void DeserializeOriginal(string filename)
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer mySerializer= new XmlSerializer(typeof(Group));
      // Reading the file requires a TextReader.
      TextReader reader = new StreamReader(filename);

      // Deserialize and cast the object.
      Group myGroup;
      myGroup = (Group) mySerializer.Deserialize(reader);

      Console.WriteLine(myGroup.GroupName);
      Console.WriteLine();
   }

   public void DeserializeOverride(string filename)
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer overRideSerializer = CreateOverrideSerializer();
      // Reading the file requires a TextReader.
      TextReader reader = new StreamReader(filename);

      // Deserialize and cast the object.
      Group myGroup;
      myGroup = (Group) overRideSerializer.Deserialize(reader);

      Console.WriteLine(myGroup.GroupName);
   }

   private XmlSerializer CreateOverrideSerializer()
   {
      SoapAttributeOverrides mySoapAttributeOverrides =
      new SoapAttributeOverrides();
      SoapAttributes soapAtts = new SoapAttributes();
      // Create a new DefaultValueAttribute object for the GroupName
      // property.
      DefaultValueAttribute newDefault =
      new DefaultValueAttribute("Team1");
      soapAtts.SoapDefaultValue = newDefault;

      mySoapAttributeOverrides.Add(typeof(Group), "GroupName",
      soapAtts);

      // Create an XmlTypeMapping that is used to create an instance
      // of the XmlSerializer. Then return the XmlSerializer object.
      XmlTypeMapping myMapping = (new SoapReflectionImporter(
      mySoapAttributeOverrides)).ImportTypeMapping(typeof(Group));
    
      XmlSerializer ser = new XmlSerializer(myMapping);
      return ser;
   }
}

Imports System.IO
Imports System.Xml
Imports System.Xml.Serialization
Imports System.Xml.Schema
Imports System.ComponentModel

Public Class Group
   ' The default is set to .NET.
   <DefaultValue(".NET")> _
   Public GroupName As String
End Class
 
Public Class Run

   Public Shared Sub Main()
   
      Dim test As Run = new Run()
      test.SerializeOriginal("SoapOriginal.xml")
      test.SerializeOverride _
      ("mySoapAttributeOverridesideAttributes.xml")
      test.DeserializeOriginal("SoapOriginal.xml")
      test.DeserializeOverride _
      ("mySoapAttributeOverridesideAttributes.xml")
   End Sub
   
   public Sub SerializeOriginal(filename As String)
       ' Create an instance of the XmlSerializer class.
      Dim mySerializer As XmlSerializer =  _
      new XmlSerializer(GetType(Group))

      ' Writing the file requires a TextWriter.
      Dim writer As TextWriter = new StreamWriter(filename)

      ' Create an instance of the class that will be serialized.
      Dim myGroup As Group = new Group()

      ' Setting the GroupName to '.NET' is like not setting it at all
      ' because it is the default value. So no value will be 
      ' serialized, and on deserialization it will appear as a blank.
      myGroup.GroupName = ".NET"

      ' Serialize the class, and close the TextWriter.
      mySerializer.Serialize(writer, myGroup)
      writer.Close()
   End Sub

   Public Sub SerializeOverride(filename As String)
   
      ' Create an instance of the XmlSerializer class
      ' that overrides the serialization.
      Dim overRideSerializer As XmlSerializer = CreateOverrideSerializer()

      ' Writing the file requires a TextWriter.
      Dim writer As TextWriter = new StreamWriter(filename)

      ' Create an instance of the class that will be serialized.
      Dim myGroup As Group = new Group()

      ' The override specifies that the default value is now 
      ' 'Team1'. So setting the GroupName to '.NET' means
      ' the value will be serialized.
      myGroup.GroupName = ".NET"
      ' Serialize the class, and close the TextWriter.
      overRideSerializer.Serialize(writer, myGroup)
       writer.Close()

   End Sub


   Public Sub DeserializeOriginal(filename As String)
   
      ' Create an instance of the XmlSerializer class.
      Dim mySerializer As XmlSerializer = new XmlSerializer(GetType(Group))
      ' Reading the file requires a TextReader.
      Dim reader As TextReader = new StreamReader(filename)

      ' Deserialize and cast the object.
      Dim myGroup As Group = CType(mySerializer.Deserialize(reader), Group)

      Console.WriteLine(myGroup.GroupName)
      Console.WriteLine()
   End Sub

   Public Sub DeserializeOverride(filename As String)
   
      ' Create an instance of the XmlSerializer class.
      Dim overRideSerializer As XmlSerializer = CreateOverrideSerializer()
      ' Reading the file requires a TextReader.
      Dim reader As TextReader = new StreamReader(filename)

      ' Deserialize and cast the object.
      Dim myGroup As Group = CType(overRideSerializer.Deserialize(reader), Group)

      Console.WriteLine(myGroup.GroupName)

   End Sub

   Private Function CreateOverrideSerializer() As XmlSerializer 
   
      Dim mySoapAttributeOverrides As SoapAttributeOverrides  = _
      New SoapAttributeOverrides()
      Dim soapAtts As SoapAttributes = New SoapAttributes()
      ' Create a new DefaultValueAttribute object for the GroupName
      ' property.
      Dim newDefault As DefaultValueAttribute = _
      new DefaultValueAttribute("Team1")
      soapAtts.SoapDefaultValue = newDefault

     mySoapAttributeOverrides.Add(GetType(Group), "GroupName", _
     soapAtts)
      
      ' Create an XmlTypeMapping that is used to create an instance 
      ' of the XmlSerializer. Then return the XmlSerializer object.
      Dim myMapping As XmlTypeMapping = _
      (New SoapReflectionImporter( _
      mySoapAttributeOverrides)).ImportTypeMapping(GetType(Group))
    
      Dim ser As XmlSerializer = new XmlSerializer(myMapping)
      return ser
   End Function
End Class

Remarks

The default value of a member can be set by applying a DefaultValueAttribute attribute to the member. If the member is being serialized as an encoded SOAP message, you can change the default value by creating a new DefaultValueAttribute, setting its Value property, and setting the SoapDefaultValue property to the object. Add the SoapAttributes to a SoapAttributeOverrides. For more details, see the SoapAttributeOverrides class overview.

Applies to

Jaa