Xpath On selected node??

  • Thread starter Thread starter probashi
  • Start date Start date
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probashi

Hi,
From the sample xml, I am trying to select a book and then select the
Click to expand...
author of the select book.

In the example code first SelectSingleNode selects a book. Second
SelectSingleNode on the book node should return the author of the
selected book (???). But I am getting the first author in the document
(Margaret Atwood), not the author of the selected book (Jane Austen).

Thanks.
Sample Code:
-----------------------------------------------
using System;
using System.IO;
using System.Xml;

public class Sample
{
public static void Main()
{

XmlDocument doc = new XmlDocument();
doc.Load("booksort.xml");

//Create an XmlNamespaceManager for resolving namespaces.
XmlNamespaceManager nsmgr = new
XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("bk", "urn:samples");

//Select the book node with the matching attribute value.
XmlNode book, author;
XmlElement root = doc.DocumentElement;
book =
root.SelectSingleNode("/descendant::book[@bk:ISBN='1-861001-57-6']",
nsmgr);
Console.WriteLine(book.OuterXml);

author = book.SelectSingleNode("/descendant::author");

Console.WriteLine(author.OuterXml);


}
-----------------------------------------------
Sample XML:
-----------------------------------------------
<?xml version="1.0" ?>
<!-- a fragment of a book store inventory database -->
<bookstore xmlns:bk="urn:samples">
<book genre="novel" publicationdate="1992" bk:ISBN="1-861002-30-1">
<title>The Handmaid's Tale</title>
<author>
<first-name>Margaret</first-name>
<last-name>Atwood</last-name>
</author>
<price>29.95</price>
</book>
<book genre="novel" publicationdate="1997" bk:ISBN="1-861001-57-8">
<title>Pride And Prejudice</title>
<author>
<first-name>Jane</first-name>
<last-name>Austen</last-name>
</author>
<price>24.95</price>
</book>

<book genre="novel" publicationdate="1991" bk:ISBN="1-861001-57-6">
<title>Emma</title>
<author>
<first-name>Jane</first-name>
<last-name>Austen</last-name>
</author>
<price>19.95</price>
</book>
<book genre="novel" publicationdate="1982" bk:ISBN="1-861001-45-3">
<title>Sense and Sensibility</title>
<author>
<first-name>Jane</first-name>
<last-name>Austen</last-name>
</author>
<price>19.95</price>
</book>
</bookstore>
 
probashi,

I believe you want to use the expression "descendant::author". I
believe using the slash bumps the expression back to the root of the
document.

Hope this helps.

--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

probashi said:
Hi,
From the sample xml, I am trying to select a book and then select the
Click to expand...
author of the select book.

In the example code first SelectSingleNode selects a book. Second
SelectSingleNode on the book node should return the author of the
selected book (???). But I am getting the first author in the document
(Margaret Atwood), not the author of the selected book (Jane Austen).

Thanks.
Sample Code:
-----------------------------------------------
using System;
using System.IO;
using System.Xml;

public class Sample
{
public static void Main()
{

XmlDocument doc = new XmlDocument();
doc.Load("booksort.xml");

//Create an XmlNamespaceManager for resolving namespaces.
XmlNamespaceManager nsmgr = new
XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("bk", "urn:samples");

//Select the book node with the matching attribute value.
XmlNode book, author;
XmlElement root = doc.DocumentElement;
book =
root.SelectSingleNode("/descendant::book[@bk:ISBN='1-861001-57-6']",
nsmgr);
Console.WriteLine(book.OuterXml);

author = book.SelectSingleNode("/descendant::author");

Console.WriteLine(author.OuterXml);


}
-----------------------------------------------
Sample XML:
-----------------------------------------------
<?xml version="1.0" ?>
<!-- a fragment of a book store inventory database -->
<bookstore xmlns:bk="urn:samples">
<book genre="novel" publicationdate="1992" bk:ISBN="1-861002-30-1">
<title>The Handmaid's Tale</title>
<author>
<first-name>Margaret</first-name>
<last-name>Atwood</last-name>
</author>
<price>29.95</price>
</book>
<book genre="novel" publicationdate="1997" bk:ISBN="1-861001-57-8">
<title>Pride And Prejudice</title>
<author>
<first-name>Jane</first-name>
<last-name>Austen</last-name>
</author>
<price>24.95</price>
</book>

<book genre="novel" publicationdate="1991" bk:ISBN="1-861001-57-6">
<title>Emma</title>
<author>
<first-name>Jane</first-name>
<last-name>Austen</last-name>
</author>
<price>19.95</price>
</book>
<book genre="novel" publicationdate="1982" bk:ISBN="1-861001-45-3">
<title>Sense and Sensibility</title>
<author>
<first-name>Jane</first-name>
<last-name>Austen</last-name>
</author>
<price>19.95</price>
</book>
</bookstore>
Click to expand...
 
probashi said:
Hi,
From the sample xml, I am trying to select a book and then select the
Click to expand...
author of the select book.

In the example code first SelectSingleNode selects a book. Second
SelectSingleNode on the book node should return the author of the
selected book (???). But I am getting the first author in the document
(Margaret Atwood), not the author of the selected book (Jane Austen).

Thanks.
Sample Code:
-----------------------------------------------
using System;
using System.IO;
using System.Xml;

public class Sample
{
public static void Main()
{

XmlDocument doc = new XmlDocument();
doc.Load("booksort.xml");

//Create an XmlNamespaceManager for resolving namespaces.
XmlNamespaceManager nsmgr = new
XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("bk", "urn:samples");

//Select the book node with the matching attribute value.
XmlNode book, author;
XmlElement root = doc.DocumentElement;
book =
root.SelectSingleNode("/descendant::book[@bk:ISBN='1-861001-57-6']",
nsmgr);
Console.WriteLine(book.OuterXml);

author = book.SelectSingleNode("/descendant::author");
Click to expand...

[...]

I can't test it right now, but I guess that should read:

author = book.SelectSingleNode("./descendant::author");

The dot is saying, select from the current branch. If you don't add it, it
will select from the root of the document.

Let me know if this works.

By the way, I think you can select the author in one statement. Check
following links for more information:

http://www.w3schools.com/xpath/
http://www.w3.org/TR/xpath

Cheers,
 
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