XmlRootAttribute.IsNullable Property
Important
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Gets or sets a value that indicates whether the XmlSerializer must serialize a member that is set to null
into the xsi:nil
attribute set to true
.
public:
property bool IsNullable { bool get(); void set(bool value); };
public bool IsNullable { get; set; }
member this.IsNullable : bool with get, set
Public Property IsNullable As Boolean
true
if the XmlSerializer generates the xsi:nil
attribute; otherwise, false
.
The following example serializes a class named Group
. The example applies the XmlRootAttribute to the class, and sets the IsNullable property to false
.
#using <System.Xml.dll>
#using <System.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;
using namespace System::Xml;
// Apply the XmlRootAttribute and set the IsNullable property to false.
[XmlRoot(IsNullable=false)]
public ref class Group
{
public:
String^ Name;
};
void SerializeObject( String^ filename )
{
XmlSerializer^ s = gcnew XmlSerializer( Group::typeid );
// Writing the file requires a TextWriter.
TextWriter^ writer = gcnew StreamWriter( filename );
// Create the object to serialize.
Group^ mygroup = nullptr;
// Serialize the object, and close the TextWriter.
s->Serialize( writer, mygroup );
writer->Close();
}
int main()
{
Console::WriteLine( "Running" );
SerializeObject( "NullDoc.xml" );
}
using System;
using System.IO;
using System.Xml.Serialization;
using System.Xml;
// Apply the XmlRootAttribute and set the IsNullable property to false.
[XmlRoot(IsNullable = false)]
public class Group
{
public string Name;
}
public class Run
{
public static void Main()
{
Console.WriteLine("Running");
Run test = new Run();
test.SerializeObject("NullDoc.xml");
}
public void SerializeObject(string filename)
{
XmlSerializer s = new XmlSerializer(typeof(Group));
// Writing the file requires a TextWriter.
TextWriter writer = new StreamWriter(filename);
// Create the object to serialize.
Group mygroup = null;
// Serialize the object, and close the TextWriter.
s.Serialize(writer, mygroup);
writer.Close();
}
}
Imports System.IO
Imports System.Xml.Serialization
Imports System.Xml
' Apply the XmlRootAttribute and set the IsNullable property to false.
<XmlRoot(IsNullable := False)> _
Public Class Group
Public Name As String
End Class
Public Class Run
Public Shared Sub Main()
Console.WriteLine("Running")
Dim test As New Run()
test.SerializeObject("NullDoc.xml")
End Sub
Public Sub SerializeObject(ByVal filename As String)
Dim s As New XmlSerializer(GetType(Group))
' Writing the file requires a TextWriter.
Dim writer As New StreamWriter(filename)
' Create the object to serialize.
Dim mygroup As Group = Nothing
' Serialize the object, and close the TextWriter.
s.Serialize(writer, mygroup)
writer.Close()
End Sub
End Class
The XML schema specification for structures allows an XML document to explicitly signal that an element's content is missing. Such an element contains the attribute xsi:nil
set to true
. For more information, see XML Schema Part 1: Structures Second Edition.
If the IsNullable property is set to true
, the xsi:nil
attribute is generated as shown in the following XML:
<?xml version="1.0" encoding="utf-8"?>
<Group xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" xsi:nil="true" />
If the IsNullable property is false
, an empty element is created as shown in the following code:
<?xml version="1.0" encoding="utf-8"?>
<Group xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" />
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
UWP | 10.0 |
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