XPathExpression.SetContext Method
Important
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When overridden in a derived class, specifies the IXmlNamespaceResolver object to use for namespace resolution.
| SetContext(IXmlNamespaceResolver) |
When overridden in a derived class, specifies the IXmlNamespaceResolver object to use for namespace resolution. |
| SetContext(XmlNamespaceManager) |
When overridden in a derived class, specifies the XmlNamespaceManager object to use for namespace resolution. |
- Source:
- XPathExpr.cs
- Source:
- XPathExpr.cs
- Source:
- XPathExpr.cs
When overridden in a derived class, specifies the IXmlNamespaceResolver object to use for namespace resolution.
public:
abstract void SetContext(System::Xml::IXmlNamespaceResolver ^ nsResolver);public abstract void SetContext(System.Xml.IXmlNamespaceResolver? nsResolver);public abstract void SetContext(System.Xml.IXmlNamespaceResolver nsResolver);abstract member SetContext : System.Xml.IXmlNamespaceResolver -> unitPublic MustOverride Sub SetContext (nsResolver As IXmlNamespaceResolver)Parameters
- nsResolver
- IXmlNamespaceResolver
An object that implements the IXmlNamespaceResolver interface to use for namespace resolution.
Exceptions
The IXmlNamespaceResolver object parameter is not derived from IXmlNamespaceResolver.
Examples
The following example shows how to use the XPath return type to determine how to process the XPath expression, and how to use the SetContext method to provide an XmlNamespaceManager object for namespace resolution.
public ref class Sample
{
public:
static void Evaluate( XPathExpression^ expr, XPathNavigator^ nav )
{
XPathNodeIterator^ i = nav->Select(expr);
switch ( expr->ReturnType )
{
case XPathResultType::Number:
Console::WriteLine( nav->Evaluate( expr ) );
break;
case XPathResultType::NodeSet:
while ( i->MoveNext() )
Console::WriteLine( i->Current );
break;
case XPathResultType::Boolean:
if ( *safe_cast<bool^>(nav->Evaluate( expr )) )
Console::WriteLine( "True!" );
break;
case XPathResultType::String:
Console::WriteLine( nav->Evaluate( expr ) );
break;
}
}
};
int main()
{
XPathDocument^ doc = gcnew XPathDocument( "contosoBooks.xml" );
XPathNavigator^ nav = doc->CreateNavigator();
XPathExpression^ expr1 = nav->Compile( ".//price/text()*10" ); // Returns a number.
XPathExpression^ expr2 = nav->Compile( "bookstore/book/price" ); // Returns a nodeset.
Sample^ MySample = gcnew Sample;
MySample->Evaluate( expr1, nav );
MySample->Evaluate( expr2, nav );
}
using System;
using System.Xml;
using System.Xml.XPath;
public class XPathExpressionExample
{
public static void Main()
{
XPathDocument document = new XPathDocument("contosoBooks.xml");
XPathNavigator navigator = document.CreateNavigator();
XPathExpression expression1 = XPathExpression.Compile(".//bk:price/text()*10"); // Returns a number.
XPathExpression expression2 = XPathExpression.Compile("bk:bookstore/bk:book/bk:price"); // Returns a nodeset.
XmlNamespaceManager manager = new XmlNamespaceManager(navigator.NameTable);
manager.AddNamespace("bk", "http://www.contoso.com/books");
expression1.SetContext(manager);
expression2.SetContext(manager);
Evaluate(expression1, navigator);
Evaluate(expression2, navigator);
}
public static void Evaluate(XPathExpression expression, XPathNavigator navigator)
{
switch (expression.ReturnType)
{
case XPathResultType.Number:
Console.WriteLine(navigator.Evaluate(expression));
break;
case XPathResultType.NodeSet:
XPathNodeIterator nodes = navigator.Select(expression);
while (nodes.MoveNext())
{
Console.WriteLine(nodes.Current.ToString());
}
break;
case XPathResultType.Boolean:
if ((bool)navigator.Evaluate(expression))
Console.WriteLine("True!");
break;
case XPathResultType.String:
Console.WriteLine(navigator.Evaluate(expression));
break;
}
}
}
Imports System.Xml
Imports System.Xml.XPath
Public Class XPathExpressionExample
Public Shared Sub Main()
Dim document As XPathDocument = New XPathDocument("contosoBooks.xml")
Dim navigator As XPathNavigator = document.CreateNavigator()
Dim expression1 As XPathExpression = XPathExpression.Compile(".//bk:price/text()*10") ' Returns a number.
Dim expression2 As XPathExpression = XPathExpression.Compile("bk:bookstore/bk:book/bk:price") ' Returns a nodeset.
Dim manager As XmlNamespaceManager = New XmlNamespaceManager(navigator.NameTable)
manager.AddNamespace("bk", "http://www.contoso.com/books")
expression1.SetContext(manager)
expression2.SetContext(manager)
Evaluate(expression1, navigator)
Evaluate(expression2, navigator)
End Sub
Public Shared Sub Evaluate(ByVal expression As XPathExpression, ByVal navigator As XPathNavigator)
Select Case expression.ReturnType
Case XPathResultType.Number
Console.WriteLine(navigator.Evaluate(expression))
Exit Sub
Case XPathResultType.NodeSet
Dim nodes As XPathNodeIterator = navigator.Select(expression)
While nodes.MoveNext()
Console.WriteLine(nodes.Current.ToString())
End While
Case XPathResultType.Boolean
If CType(navigator.Evaluate(expression), Boolean) Then
Console.WriteLine("True!")
End If
Case XPathResultType.String
Console.WriteLine(navigator.Evaluate(expression))
End Select
End Sub
End Class
The example takes the contosoBooks.xml file as 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>
Remarks
Namespace resolution is supported using classes that implement the IXmlNamespaceResolver interface, such as the XmlNamespaceManager class. The XmlNamespaceManager stores prefix and namespace Uniform Resource Identifier (URI) mappings. If the XPathExpression requires namespace resolution, the prefix and namespace URI pair must be added to an object, such as the XmlNamespaceManager class, which implements the IXmlNamespaceResolver interface, and the SetContext method must be called to specify the IXmlNamespaceResolver interface object to use for namespace resolution.
The following are important notes to consider when using the SetContext method.
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 object that contains a prefix and namespace URI to handle the default namespace.
You can also supply an IXmlNamespaceResolver interface object for namespace resolution to the Compile method when you create your XPathExpression object.
SetContext accepts XsltContext as a namespace resolver, so you can implement a custom context and use functions and variables based on IXsltContextFunction and IXsltContextVariable. The XPath expression will execute them. For more information, see User Defined Functions and Variables.
See also
- SetContext(XmlNamespaceManager)
- IXmlNamespaceResolver
- Compile(String, IXmlNamespaceResolver)
- User Defined Functions and Variables
Applies to
.NET 10 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, 10 |
| .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 |
- Source:
- XPathExpr.cs
- Source:
- XPathExpr.cs
- Source:
- XPathExpr.cs
When overridden in a derived class, specifies the XmlNamespaceManager object to use for namespace resolution.
public:
abstract void SetContext(System::Xml::XmlNamespaceManager ^ nsManager);public abstract void SetContext(System.Xml.XmlNamespaceManager nsManager);abstract member SetContext : System.Xml.XmlNamespaceManager -> unitPublic MustOverride Sub SetContext (nsManager As XmlNamespaceManager)Parameters
- nsManager
- XmlNamespaceManager
An XmlNamespaceManager object to use for namespace resolution.
Exceptions
The XmlNamespaceManager object parameter is not derived from the XmlNamespaceManager class.
Examples
The following example shows how to use the XPath return type to determine how to process the XPath expression, and how to use the SetContext method to provide an XmlNamespaceManager object for namespace resolution.
public ref class Sample
{
public:
static void Evaluate( XPathExpression^ expr, XPathNavigator^ nav )
{
XPathNodeIterator^ i = nav->Select(expr);
switch ( expr->ReturnType )
{
case XPathResultType::Number:
Console::WriteLine( nav->Evaluate( expr ) );
break;
case XPathResultType::NodeSet:
while ( i->MoveNext() )
Console::WriteLine( i->Current );
break;
case XPathResultType::Boolean:
if ( *safe_cast<bool^>(nav->Evaluate( expr )) )
Console::WriteLine( "True!" );
break;
case XPathResultType::String:
Console::WriteLine( nav->Evaluate( expr ) );
break;
}
}
};
int main()
{
XPathDocument^ doc = gcnew XPathDocument( "contosoBooks.xml" );
XPathNavigator^ nav = doc->CreateNavigator();
XPathExpression^ expr1 = nav->Compile( ".//price/text()*10" ); // Returns a number.
XPathExpression^ expr2 = nav->Compile( "bookstore/book/price" ); // Returns a nodeset.
Sample^ MySample = gcnew Sample;
MySample->Evaluate( expr1, nav );
MySample->Evaluate( expr2, nav );
}
using System;
using System.Xml;
using System.Xml.XPath;
public class XPathExpressionExample
{
public static void Main()
{
XPathDocument document = new XPathDocument("contosoBooks.xml");
XPathNavigator navigator = document.CreateNavigator();
XPathExpression expression1 = XPathExpression.Compile(".//bk:price/text()*10"); // Returns a number.
XPathExpression expression2 = XPathExpression.Compile("bk:bookstore/bk:book/bk:price"); // Returns a nodeset.
XmlNamespaceManager manager = new XmlNamespaceManager(navigator.NameTable);
manager.AddNamespace("bk", "http://www.contoso.com/books");
expression1.SetContext(manager);
expression2.SetContext(manager);
Evaluate(expression1, navigator);
Evaluate(expression2, navigator);
}
public static void Evaluate(XPathExpression expression, XPathNavigator navigator)
{
switch (expression.ReturnType)
{
case XPathResultType.Number:
Console.WriteLine(navigator.Evaluate(expression));
break;
case XPathResultType.NodeSet:
XPathNodeIterator nodes = navigator.Select(expression);
while (nodes.MoveNext())
{
Console.WriteLine(nodes.Current.ToString());
}
break;
case XPathResultType.Boolean:
if ((bool)navigator.Evaluate(expression))
Console.WriteLine("True!");
break;
case XPathResultType.String:
Console.WriteLine(navigator.Evaluate(expression));
break;
}
}
}
Imports System.Xml
Imports System.Xml.XPath
Public Class XPathExpressionExample
Public Shared Sub Main()
Dim document As XPathDocument = New XPathDocument("contosoBooks.xml")
Dim navigator As XPathNavigator = document.CreateNavigator()
Dim expression1 As XPathExpression = XPathExpression.Compile(".//bk:price/text()*10") ' Returns a number.
Dim expression2 As XPathExpression = XPathExpression.Compile("bk:bookstore/bk:book/bk:price") ' Returns a nodeset.
Dim manager As XmlNamespaceManager = New XmlNamespaceManager(navigator.NameTable)
manager.AddNamespace("bk", "http://www.contoso.com/books")
expression1.SetContext(manager)
expression2.SetContext(manager)
Evaluate(expression1, navigator)
Evaluate(expression2, navigator)
End Sub
Public Shared Sub Evaluate(ByVal expression As XPathExpression, ByVal navigator As XPathNavigator)
Select Case expression.ReturnType
Case XPathResultType.Number
Console.WriteLine(navigator.Evaluate(expression))
Exit Sub
Case XPathResultType.NodeSet
Dim nodes As XPathNodeIterator = navigator.Select(expression)
While nodes.MoveNext()
Console.WriteLine(nodes.Current.ToString())
End While
Case XPathResultType.Boolean
If CType(navigator.Evaluate(expression), Boolean) Then
Console.WriteLine("True!")
End If
Case XPathResultType.String
Console.WriteLine(navigator.Evaluate(expression))
End Select
End Sub
End Class
The example takes the contosoBooks.xml file as 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>
Remarks
Namespace resolution is supported using the XmlNamespaceManager class which stores prefix and namespace Uniform Resource Identifier (URI) mappings. If the XPathExpression requires namespace resolution, the prefix and namespace URI pair must be added to the XmlNamespaceManager object and the SetContext method must be called to specify the XmlNamespaceManager object to use for namespace resolution.
The following are important notes to consider when using the SetContext method.
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 object that contains a prefix and namespace URI to handle the default namespace.
You can also supply an IXmlNamespaceResolver object for namespace resolution to the Compile method when you create your XPathExpression object.
SetContext accepts XsltContext as a namespace resolver, so you can implement a custom context and use functions and variables based on IXsltContextFunction and IXsltContextVariable. The XPath expression will execute them. For more information, see User Defined Functions and Variables.
See also
- XmlNamespaceManager
- SetContext(IXmlNamespaceResolver)
- IXmlNamespaceResolver
- Compile(String, IXmlNamespaceResolver)
- User Defined Functions and Variables
Applies to
.NET 10 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, 10 |
| .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 |
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