Accessing the nillness of an element

XML elements can be nil, which is not the same as being null. An element that is nil must have no child elements, but can have attributes. Additionally, an XSD can define whether an element is nillable, meaning it is allowed to be nil.

If an XSD-based element is nillable, the XmlElement object exposes a property with the name $Nil. All non-XSD elements also have this property, but in such cases it is called Nil (with no $ prefix).

Note: For XSD-based elements not marked as nillable, this property is unsupported. In the Gosu editor, if you attempt to use the $Nil property, Gosu generates a deprecation warning.

Setting this property on an element to true affects whether Gosu adds an xsi:nil attribute to the element upon serialization. Getting this property returns the state of that flag (true or false).

Note: Nillability is an aspect of XSD-based elements, not an aspect of the XSD type itself.

Example

The following XSD contains defines an element that is nillable.

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:element name="Element1" type="xsd:int" nillable="true"/>
</xsd:schema>

The following code demonstrates how to set the $Nil property of the element.

uses examples.pl.gosu.xml.myschema.Element1
var xml = new Element1()
xml.$Nil = true
xml.print()

This code prints the following:

<?xml version="1.0"?>
<Element1 xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>