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Método XPathNavigator.CreateAttributes ()

 

Publicado: octubre de 2016

Devuelve un objeto XmlWriter usado para crear nuevos atributos en el elemento actual.

Espacio de nombres:   System.Xml.XPath
Ensamblado:  System.Xml (en System.Xml.dll)

public virtual XmlWriter CreateAttributes()

Valor devuelto

Type: System.Xml.XmlWriter

Objeto XmlWriter usado para crear nuevos atributos en el elemento actual.

Exception Condition
InvalidOperationException

XPathNavigator no está colocado en un nodo de elemento.

NotSupportedException

XPathNavigator no admite la edición.

The following are important notes to consider when using the M:System.Xml.XPath.XPathNavigator.CreateAttributes method.

  • When the T:System.Xml.XPath.XPathNavigator is positioned on an element, the new attributes created by the T:System.Xml.XPath.XPathNavigator method are placed at the end of the attribute list of the current element.

  • The new attributes are not inserted until the M:System.Xml.XmlWriter.Close method of the T:System.Xml.XmlWriter object is called.

  • If the namespace prefix specified is F:System.String.Empty or null, the prefix for the namespace URI of the new attribute is obtained from the current namespaces in-scope. If there is no namespace prefix assigned to the specified namespace URI at the current scope, a namespace prefix is automatically generated. For example to create a new attribute on an element in the default namespace of the contosoBooks.xml file, (xmlns="http://www.contoso.com/books"), you specify null or F:System.String.Empty for both the namespace prefix and namespace URI parameters. Specifying http://www.contoso.com/books as the namespace URI parameter will cause the M:System.Xml.XPath.XPathNavigator.CreateAttribute(System.String,System.String,System.String,System.String) method to auto generate a namespace prefix for the new attribute.

  • If the new attribute created is a namespace node which conflicts with a namespace declaration on the element, either because the namespace prefix chosen is used by another namespace declaration at the same scope, or because the prefix chosen is the same as that of the element but is bound to a different namespace URI, an exception is thrown.

  • The T:System.Xml.XmlWriter object returned may only be used to create attributes. Calling other T:System.Xml.XmlWriter object methods that do not create attributes throws an exception.

  • The M:System.Xml.XPath.XPathNavigator.CreateAttributes method does not affect the position of the T:System.Xml.XPath.XPathNavigator.

In the following example, new discount and currency attributes are created on the price child element of the first book element in the contosoBooks.xml file using the T:System.Xml.XmlWriter object returned from the M:System.Xml.XPath.XPathNavigator.CreateAttributes method.

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.MoveToChild("price", "http://www.contoso.com/books");

XmlWriter attributes = navigator.CreateAttributes();

attributes.WriteAttributeString("discount", "1.00");
attributes.WriteAttributeString("currency", "USD");
attributes.Close();

navigator.MoveToParent();
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
Disponible desde 2.0
Silverlight
Disponible desde 4.0
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