Advanced XPath Analyzer

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Introduction

This is an advanced version of the good XPath Analyzer done by Enrico Elizar Samuel (http://www.codeproject.com/aspnet/xpathanalyzer.asp). Advanced XPath Analyzer has been re-written in C# and supports namespaces resolution and navigation.

Notes about the code

The main difference from the original XPath Analyzer is that you can navigate into an XML document using qualified names. It is also possibile to have a default namespace in the XML document. In this case a the namespace prefix will be def, so that you can refer to it in your xpath expression.

Let's say that, for example, we have an XML document that looks like this one:

<?xml version="1.0" encoding="utf-8"?>
<items link="~/Html/Default.htm" xmlns=http://site/menu 
    xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance 
    xsi:schemalocation="http://site/menu menu.xsd">
    <item title="Products" link="#">
        <item title="Product 1" link="#"/>
        <item title="Product 2" link="#"/>
        <item title="Product 3" link="#"/>
        <item title="Product 4" link= "#"/>
    </item>
    <item title="Services" link="#">
        <item title="Service 1" link="#" />
        <item title="Service 2" link="#" />
    </item>
    <item title="People" link="#"/>
    <item title="Opening Hours" link="#"/>
    <item title="Prices" link="#"/>
    <item title="Contacts" link="#"/>
</items>

That is, as you may have guessed, the navigation menu of a simple website. If you need to get the Product 3 link, you should write an XPath query like:

/items/item[@title='Products']

but this query won't give any result! This because you need to specify that the elements items and item belongs to the default namespace http://site/menu as it really is, otherwise the parser will understand that they aren't associated with any namespace.
So, the correct query is:

in order to run correctly this query you first need to define that the prefix def points to the default namespace URI. With the Advanced XPath Analyer you can just manually add the namespace or ask to it to detect it automatically, but what really happens behind the scenes?
Three steps are needed to make the XPath query run without errors:

1. Define an XmlNamespaceManager with all the needed namespaces
2. Create an XPathExpression that contains the relative XPath Expression
3. Assign the created XmlNamespaceManager object to that XPathExpression

That, in pratice, means to write something like:

XmlNamespaceManager namespaceManager = 
    new XmlNamespaceManager(new NameTable());
namespaceManager.AddNamespace(prefix, uri);
XPathExpression expression = navigator.Compile(xpathQuery);
expression.SetContext(namespaceManager);

Where prefix and uri are the variables that contains the relative values, and navigator is the XPathNavigator that you're using to navigate through the document.

Using the program

You have to specify the XML source file (which can be a file on your hard disk or a file somewhere in the web) and then the XPath Query you'd like to test. You can also specify a SQLXML url so that you can test your SQLXML Queries. If your XML uses namespaces you have to add it in the left panel so that you can use them in your XPath Query, otherwise you can detect it automatically, clickin' on the Detect Namespace button. Of course remember to do this before you analyze the XPath Query!

Location of XML document:

http://localhost/nwind/schema/schema1.xsd/Employees?root=root

XPath query:

//root/Employees

History

• v 1.0: First version
• v 1.1: Added automatic namespace discovery