XPathNavigator.PrependChildElement Method

Creates a new child element at the beginning of the list of child nodes of the current node using the namespace prefix, local name, and namespace URI specified with the value specified.

Namespace:  System.Xml.XPath
Assembly:  System.Xml (in System.Xml.dll)

public virtual void PrependChildElement(
	string prefix,
	string localName,
	string namespaceURI,
	string value
)

Parameters

prefix
Type: System.String

The namespace prefix of the new child element (if any).

localName
Type: System.String

The local name of the new child element (if any).

namespaceURI
Type: System.String

The namespace URI of the new child element (if any). Empty and null are equivalent.

value
Type: System.String

The value of the new child element. If Empty or null are passed, an empty element is created.

ExceptionCondition
InvalidOperationException

The current node the XPathNavigator is positioned on does not allow a new child node to be prepended.

NotSupportedException

The XPathNavigator does not support editing.

Prepending a child node adds the new node to the beginning of the list of child nodes for the current node. For example, when three child nodes exist for an element, the prepended node becomes the first child node. If no child nodes exist, then a new child node is created.

Namespace prefix and URI values can be obtained by using the LookupPrefix or LookupNamespace method. For example, the following syntax prepends a child element by using the in-scope namespace xmlns:bk="http://www.contoso.com/books":

navigator.PrependChildElement(navigator.Prefix, "pages", LookupNamespaceURI(navigator.Prefix), String.Empty)

This creates the new child <bk:pages/> element.

The following are important notes to consider when using the PrependChildElement method.

  • If the namespace prefix specified is null or String.Empty, then the prefix for the namespace URI of the new element is obtained from the current namespaces in-scope. If there is no namespace prefix assigned to the specified namespace URI at the current scope, then a namespace prefix is automatically generated.

  • The PrependChildElement method is valid only when the XPathNavigator is positioned on an element node.

  • The PrependChildElement method does not affect the position of the XPathNavigator.

In the following example, a new pages child element is prepended to the beginning of the list of child elements of the first book element in the contosoBooks.xml file.

XmlDocument document = new XmlDocument();
document.Load("contosoBooks.xml");
XPathNavigator navigator = document.CreateNavigator();

navigator.MoveToChild("bookstore", "http://www.contoso.com/books");
navigator.MoveToChild("book", "http://www.contoso.com/books");

navigator.PrependChildElement(navigator.Prefix, "pages", navigator.LookupNamespace(navigator.Prefix), "100");

Console.WriteLine(navigator.OuterXml);

The example takes the contosoBooks.xml file as an input.

<?xml version="1.0" encoding="utf-8" ?>
<bookstore xmlns="http://www.contoso.com/books">
    <book genre="autobiography" publicationdate="1981-03-22" ISBN="1-861003-11-0">
        <title>The Autobiography of Benjamin Franklin</title>
        <author>
            <first-name>Benjamin</first-name>
            <last-name>Franklin</last-name>
        </author>
        <price>8.99</price>
    </book>
    <book genre="novel" publicationdate="1967-11-17" ISBN="0-201-63361-2">
        <title>The Confidence Man</title>
        <author>
            <first-name>Herman</first-name>
            <last-name>Melville</last-name>
        </author>
        <price>11.99</price>
    </book>
    <book genre="philosophy" publicationdate="1991-02-15" ISBN="1-861001-57-6">
        <title>The Gorgias</title>
        <author>
            <name>Plato</name>
        </author>
        <price>9.99</price>
    </book>
</bookstore>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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