XPath visually - Script Tutorials

XPath is one of important keys to understanding of XSLT. And at first time we usually looking for any information (better – places where we can play online) – how to get different values in branch of XML tree. In this article I`ll give you all important information and will show how to work with XPath in samples.

As example we have next source XML:

<?xml version="1.0"?> 
  
<bookstore specialty="novel"> 
  
  <book style="autobiography"> 
  
    <author> 
  
      <first-name>Joe</first-name> 
  
      <last-name>Bob</last-name> 
  
      <award>Trenton Literary Review Honorable Mention</award> 
  
    </author> 
  
    <price>12</price> 
  
  </book> 
  
  <book style="textbook"> 
  
    <author> 
  
      <first-name>Mary</first-name> 
  
      <last-name>Bob</last-name> 
  
      <publication>Selected Short Stories of 
  
        <first-name>Mary</first-name> 
  
        <last-name>Bob</last-name> 
  
      </publication> 
  
    </author> 
  
    <price>55</price> 
  
  </book> 
  
  <magazine style="glossy" frequency="monthly"> 
  
    <price>2.50</price> 
  
    <subscription price="24" per="year"/> 
  
  </magazine> 
  
  <book style="novel" id="myfave"> 
  
    <author> 
  
      <first-name>Toni</first-name> 
  
      <last-name>Bob</last-name> 
  
      <degree from="Trenton U">B.A.</degree> 
  
      <degree from="Harvard">Ph.D.</degree> 
  
      <award>Pulitzer</award> 
  
      <publication>Still in Trenton</publication> 
  
      <publication>Trenton Forever</publication> 
  
    </author> 
  
    <price intl="Canada" exchange="0.7">6.50</price> 
  
    <excerpt> 
  
      <p>It was a dark and stormy night.</p> 
  
      <p>But then all nights in Trenton seem dark and 
  
      stormy to someone who has gone through what 
  
      <emph>I</emph> have.</p> 
  
      <definition-list> 
  
        <term>Trenton</term> 
  
        <definition>misery</definition> 
  
      </definition-list> 
  
    </excerpt> 
  
  </book> 
  
</bookstore>

This is some bookstore listing

Here are list of rules which we can use in XPath:

Different levels in tree separate via / symbol. This example will return array with infos of all authors: bookstore/book/author
Access to attributes we can obtain via @ symbol. That example will return us price of magazine subscription: bookstore/magazine/subscription/@price
Inside [] we can use number value to tell which (by order) element will need to receive. This example will return us price of second book: bookstore/book[2]/price
Also, we can use subpaths in [] and use this as check, are necessary elements present in our tree or not. Example – get all books with style=novel: bookstore/book[@style=”novel”]
Another example – get all books with excerpts: bookstore/book[excerpt]
Another example – get all books if author have any awards: bookstore/book[author[award]]
Or – get all authors who have any awards: bookstore/book/author[award]
Or we can add some logic – get all books if author Don`t have awards: bookstore/book[author[not(award)]]
And last sample – get all books with price from 10 and 20: bookstore/book[price < 20 and price > 10]

Interesting, isn`t it? Now, how we can use that. In first sample – we will store some defined value into variable:

   1 <xsl:variable name="magSubPrice" select="bookstore/magazine/subscription/@price"/> 
  

Now we will walk through array of located elements:

<xsl:for-each select="bookstore/book/author"> 
  
    // do some actions with authors 
  
</xsl:for-each>

And, here are one interesting service: http://xpath.me/ – where you will able to play with all our samples online. It will allow you to feel all this by self. Very nice and easy service.

Conclusion

I hope that today’s article will very useful for your projects. Will glad if this will help you in your work. Good luck!