XPathNavigator.Select Method

Definition

Selects a node set, using the specified XPath expression.

Overloads

Select(String)

Selects a node set, using the specified XPath expression.

Select(XPathExpression)

Selects a node set using the specified XPathExpression.

Select(String, IXmlNamespaceResolver)

Selects a node set using the specified XPath expression with the IXmlNamespaceResolver object specified to resolve namespace prefixes.

Select(String)

Source:
XPathNavigator.cs
Source:
XPathNavigator.cs
Source:
XPathNavigator.cs

Selects a node set, using the specified XPath expression.

public virtual System.Xml.XPath.XPathNodeIterator Select (string xpath);

Parameters

xpath
String

A String representing an XPath expression.

Returns

An XPathNodeIterator pointing to the selected node set.

Exceptions

The XPath expression contains an error or its return type is not a node set.

The XPath expression is not valid.

Examples

The following example uses the Select method to select a node set.

XPathDocument document = new XPathDocument("books.xml");
XPathNavigator navigator = document.CreateNavigator();

XPathNodeIterator nodes = navigator.Select("/bookstore/book");
nodes.MoveNext();
XPathNavigator nodesNavigator = nodes.Current;

XPathNodeIterator nodesText = nodesNavigator.SelectDescendants(XPathNodeType.Text, false);

while (nodesText.MoveNext())
    Console.WriteLine(nodesText.Current.Value);

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

<?xml version="1.0" encoding="utf-8" ?>   
<bookstore>  
    <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>  

Remarks

The context for the selection is the position of the XPathNavigator when this method is called. After calling this method, the XPathNodeIterator returned represents the set of selected nodes. Use MoveNext method of the XPathNodeIterator to iterate over the selected node set.

The following C# code iterates over the selected set of nodes.

XPathNodeIterator iterator = nav.Select("/bookstore/book");  
while (iterator.MoveNext())  
{  
    Console.WriteLine(Iterator.Current.Name);  
}  

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

See also

Applies to

.NET 9 and other versions
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

Select(XPathExpression)

Source:
XPathNavigator.cs
Source:
XPathNavigator.cs
Source:
XPathNavigator.cs

Selects a node set using the specified XPathExpression.

public virtual System.Xml.XPath.XPathNodeIterator Select (System.Xml.XPath.XPathExpression expr);

Parameters

expr
XPathExpression

An XPathExpression object containing the compiled XPath query.

Returns

An XPathNodeIterator that points to the selected node set.

Exceptions

The XPath expression contains an error or its return type is not a node set.

The XPath expression is not valid.

Examples

The following example uses the Select method to select a node set.

XPathDocument document = new XPathDocument("books.xml");
XPathNavigator navigator = document.CreateNavigator();

XPathExpression query = navigator.Compile("/bookstore/book");
XPathNodeIterator nodes = navigator.Select(query);
XPathNavigator nodesNavigator = nodes.Current;

XPathNodeIterator nodesText = nodesNavigator.SelectDescendants(XPathNodeType.Text, false);

while (nodesText.MoveNext())
{
    Console.WriteLine(nodesText.Current.Value);
}

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

<?xml version="1.0" encoding="utf-8" ?>   
<bookstore>  
    <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>  

Remarks

The context for the selection is the position of the XPathNavigator when you called this method. After you call this method, the XPathNodeIterator returned represents the set of selected nodes. Use MoveNext on the XPathNodeIterator to iterate over the selected node set.

The following C# code iterates over the selected set of nodes.

XPathNodeIterator ni = nav.Select(expr);  
while (ni.MoveNext())  
{  
    Console.WriteLine(ni.Current.Name);  
}  

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

For example, suppose the document contains the following XML nodes.

<bookstore xmlns:bk='urn:samples'>  
    <book bk:ISBN='1-325-0980'>  
        <title>Pride And Prejudice</title>  
    </book>  
</bookstore>  

In this case, the following C# code selects the bk:ISBN node.

XPathExpression expr = nav.Compile("book/@bk:ISBN");  
XmlNamespaceManager mngr = new XmlNamespaceManager(new NameTable());  
mngr.AddNamespace("bk","urn:samples");  
expr.SetContext(mngr);  
XPathNodeIterator ni = nav.Select(expr);  

Note

If the XPathExpression does not include a prefix, it is assumed that the namespace URI is the empty namespace. If your XML includes a default namespace, you must still use the SetContext method and provide an XmlNamespaceManager that contains a prefix and namespace URI to handle the default namespace.

For example, suppose you have the following XML.

<bookstore xmlns="http://www.lucernepublishing.com">  
    <book>  
        <title>Pride And Prejudice</title>  
    </book>  
</bookstore>  

In this case, the following C# code selects all book nodes:

XmlNamespaceManager nsmgr = new XmlNamespaceManager(nav.NameTable);  
nsmgr.AddNamespace("ab", "http://www.lucernepublishing.com");  
XPathExpression expr;  
expr = nav.Compile("//ab:book");  
expr.SetContext(nsmgr);  
XPathNodeIterator ni = nav.Select(expr);  

This method has no effect on the state of the XPathNavigator.

See also

Applies to

.NET 9 and other versions
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

Select(String, IXmlNamespaceResolver)

Source:
XPathNavigator.cs
Source:
XPathNavigator.cs
Source:
XPathNavigator.cs

Selects a node set using the specified XPath expression with the IXmlNamespaceResolver object specified to resolve namespace prefixes.

public virtual System.Xml.XPath.XPathNodeIterator Select (string xpath, System.Xml.IXmlNamespaceResolver? resolver);
public virtual System.Xml.XPath.XPathNodeIterator Select (string xpath, System.Xml.IXmlNamespaceResolver resolver);

Parameters

xpath
String

A String representing an XPath expression.

resolver
IXmlNamespaceResolver

The IXmlNamespaceResolver object used to resolve namespace prefixes.

Returns

An XPathNodeIterator that points to the selected node set.

Exceptions

The XPath expression contains an error or its return type is not a node set.

The XPath expression is not valid.

Examples

The following example illustrates selecting a node set using the Select method with the XmlNamespaceManager object specified to resolve namespace prefixes in the XPath expression.

XPathDocument document = new XPathDocument("contosoBooks.xml");
XPathNavigator navigator = document.CreateNavigator();
XmlNamespaceManager manager = new XmlNamespaceManager(navigator.NameTable);
manager.AddNamespace("bk", "http://www.contoso.com/books");

XPathNodeIterator nodes = navigator.Select("/bk:bookstore/bk:book/bk:price", manager);
// Move to the first node bk:price node
if(nodes.MoveNext())
{
    // now nodes.Current points to the first selected node
    XPathNavigator nodesNavigator = nodes.Current;

    //select all the descendants of the current price node
    XPathNodeIterator nodesText =
       nodesNavigator.SelectDescendants(XPathNodeType.Text, false);

    while(nodesText.MoveNext())
    {
       Console.WriteLine(nodesText.Current.Value);
    }
}

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>  

Applies to

.NET 9 and other versions
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 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