XPathNavigator.Select XPathNavigator.Select XPathNavigator.Select XPathNavigator.Select Method

Definition

Selects a node set, using the specified XPath expression.

Overloads

Select(String) Select(String) Select(String) Select(String)

Selects a node set, using the specified XPath expression.

Select(XPathExpression) Select(XPathExpression) Select(XPathExpression) Select(XPathExpression)

Selects a node set using the specified XPathExpression.

Select(String, IXmlNamespaceResolver) Select(String, IXmlNamespaceResolver) Select(String, IXmlNamespaceResolver) Select(String, IXmlNamespaceResolver)

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

Select(String) Select(String) Select(String) Select(String)

Selects a node set, using the specified XPath expression.

public:
 virtual System::Xml::XPath::XPathNodeIterator ^ Select(System::String ^ xpath);
public virtual System.Xml.XPath.XPathNodeIterator Select (string xpath);
abstract member Select : string -> System.Xml.XPath.XPathNodeIterator
override this.Select : string -> System.Xml.XPath.XPathNodeIterator
Public Overridable Function Select (xpath As String) As XPathNodeIterator

Parameters

xpath
String String String String

A String representing an XPath expression.

Returns

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 = gcnew 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);
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);
Dim document As XPathDocument = New XPathDocument("books.xml")
Dim navigator As XPathNavigator = document.CreateNavigator()

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

Dim nodesText As XPathNodeIterator = nodesNavigator.SelectDescendants(XPathNodeType.Text, False)

While nodesText.MoveNext()
    Console.WriteLine(nodesText.Current.Value)
End While

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

Select(XPathExpression) Select(XPathExpression) Select(XPathExpression) Select(XPathExpression)

Selects a node set using the specified XPathExpression.

public:
 virtual System::Xml::XPath::XPathNodeIterator ^ Select(System::Xml::XPath::XPathExpression ^ expr);
public virtual System.Xml.XPath.XPathNodeIterator Select (System.Xml.XPath.XPathExpression expr);
abstract member Select : System.Xml.XPath.XPathExpression -> System.Xml.XPath.XPathNodeIterator
override this.Select : System.Xml.XPath.XPathExpression -> System.Xml.XPath.XPathNodeIterator
Public Overridable Function Select (expr As XPathExpression) As XPathNodeIterator

Parameters

expr
XPathExpression XPathExpression XPathExpression XPathExpression

An XPathExpression object containing the compiled XPath query.

Returns

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 = gcnew 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);
      }
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);
}
Dim document As XPathDocument = New XPathDocument("books.xml")
Dim navigator As XPathNavigator = document.CreateNavigator()

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

Dim nodesText As XPathNodeIterator = nodesNavigator.SelectDescendants(XPathNodeType.Text, False)

While nodesText.MoveNext()
    Console.WriteLine(nodesText.Current.Value)
End While

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

Select(String, IXmlNamespaceResolver) Select(String, IXmlNamespaceResolver) Select(String, IXmlNamespaceResolver) Select(String, IXmlNamespaceResolver)

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(System::String ^ xpath, System::Xml::IXmlNamespaceResolver ^ resolver);
public virtual System.Xml.XPath.XPathNodeIterator Select (string xpath, System.Xml.IXmlNamespaceResolver resolver);
abstract member Select : string * System.Xml.IXmlNamespaceResolver -> System.Xml.XPath.XPathNodeIterator
override this.Select : string * System.Xml.IXmlNamespaceResolver -> System.Xml.XPath.XPathNodeIterator
Public Overridable Function Select (xpath As String, resolver As IXmlNamespaceResolver) As XPathNodeIterator

Parameters

xpath
String String String String

A String representing an XPath expression.

Returns

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 = gcnew XPathDocument("contosoBooks.xml");
      XPathNavigator^ navigator = document->CreateNavigator();

      XmlNamespaceManager^ manager = gcnew 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);
          }
      }
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);
    }
}
Dim document As XPathDocument = New XPathDocument("contosoBooks.xml")
Dim navigator As XPathNavigator = document.CreateNavigator()

Dim manager As XmlNamespaceManager = New XmlNamespaceManager(navigator.NameTable)
manager.AddNamespace("bk", "http://www.contoso.com/books")

Dim nodes As XPathNodeIterator = navigator.Select("/bk:bookstore/bk:book/bk:price", manager)
' Move to the first node bk:price node.
If (nodes.MoveNext()) Then
    ' Now nodes.Current points to the first selected node.
    Dim nodesNavigator As XPathNavigator = nodes.Current

    ' Select all the descendants of the current price node.
    Dim nodesText As XPathNodeIterator = nodesNavigator.SelectDescendants(XPathNodeType.Text, False)

    While nodesText.MoveNext()
        Console.WriteLine(nodesText.Current.Value)
    End While
End If

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