XmlNode.BaseURI Property

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlNode.cs

Gets the base URI of the current node.

public:
 virtual property System::String ^ BaseURI { System::String ^ get(); };

public virtual string BaseURI { get; }

member this.BaseURI : string

Public Overridable ReadOnly Property BaseURI As String

Property Value

String

The location from which the node was loaded or String.Empty if the node has no base URI.

Remarks

A networked XML document is comprised of chunks of data aggregated using various W3C standard inclusion mechanisms and therefore contains nodes that come from different places. The BaseURI tells you where these nodes came from.

The value of this property varies depending on the node type. For example, Document nodes return the location of the XmlDocument object. Nodes which are child nodes of external EntityReference nodes return the location of the entity itself. For example, consider the following XML document:

<!DOCTYPE item [
<!ENTITY xyz SYSTEM "a/b.xml">
]>
<item num='123'>&xyz;</item>

where the external entity a/b.xml contains the XML text: <test>123</test>.

If the document is loaded from http://server/mydata.xml, BaseURI returns the following:

NodeType	Name	BaseURI
Attribute	num	http://server/mydata.xml
Document	#document	http://server/mydata.xml
DocumentType	item	http://server/mydata.xml
Entity	xyz	http://server/mydata.xml
Element	item	http://server/mydata.xml
EntityReference	xyz	http://server/mydata.xml
Element	test	http://server/a/b.xml
Text	#text	http://server/a/b.xml

BaseURI looks for entity reference boundaries, so if entities are expanded this information is not preserved and this property returns the location of the XmlDocument object in all cases.

As a second example, given the following XML document:

<!DOCTYPE Mydata SYSTEM "http://localhost/doctype.dtd">
<baa>&xyz;</baa>

where the DTD file contains the following:

<!ENTITY xyz <E1>My Data</E1>
<!ELEMENT baa #PCDATA>
<!ATTLIST baa attr1 "woof">

If the XML document is loaded from http://localhost/mydata.xml, BaseURI returns the following for each of the nodes:

NodeType	Name	BaseURI
Document	#document	http://localhost/mydata.xml
DocumentType	Mydata	http://localhost/mydata.xml The XmlDocumentType.SystemId or XmlDocumentType.PublicId properties can be used to identify where the DTD file was loaded from.
Element	baa	http://localhost/mydata.xml
Entity	xyz	http://localhost/doctype.dtd
EntityReference	xyz	http://localhost/mydata.xml
Attribute	woof	http://localhost/mydata.xml

Note

The base URI of a default attribute is the same as the base URI of the element to which they belong.

This property is a Microsoft extension to the Document Object Model (DOM).