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PHP DOM Builder API

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Elements finding

Actually, DOM is hierarchical organization and one selecting criterion is not useful sometimes. What should we do if we want to find all A link tags with H2 header parent tags, or all links with HREF attributes which have the same values and are contained in DIV blocks? For this ways, we should use a find method.

Let's take previous article document example, here is it:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head>
    <title>PHP DOM Builder test page</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"></meta>
  </head>
  <body>
    <div id="content">
      <h1>
        Header
      </h1>
      <div class="article" id="id_article">
        <h2>
          Article 1
        </h2>
        <p>
          <a href="google.com">Text 1</a>
        </p>
      </div>
      <div class="article print">
        <h2>
          <a href="/article/">Article 2</a>
        </h2>
        <p>
          <a href="baigudin.software">Text 2</a>
        </p>
      </div>
    </div>
    <div id="footer">
      <p>
        &copy; copyright 2016
      </p>
    </div>
  </body>
</html> 

And try to find something:

<?php
$document
->find('#content');       // Find elements with id=content
$document->find('div#content');    // Find DIV with id=content
$document->find('.article');       // Find elements with class=article
$document->find('div.article');    // Find DIV elements with class=article
$document->find('.article.print'); // Find elements with class=article and print
$document->find('h2');             // Find H2 elements
$document->find('h1, h2');         // Find H1 and H2 elements
?> 

As you can see, query string corresponds to CSS Styling Tables. If we remember that DOM is hierarchical organization, we can find like this:

<?php
$document
->find('p a');      // Find A elements which are contained in P elements
$document->find('div h2 a'); // Find A elements in H2 elements which in DIV elements
?>

We can find elements by its attributes:

<?php
$document
->find('a[href]');                   // All links with href attribute
$document->find('a[href=baigudin.software]'); // All links with href=baigudin.software
?>

It is not difficult to understand that the find method finds child elements. So, parents method is exist too. Itfindsdirectparentelements.

<?php
// Find DIV elements with class=article which are parent of A elements
$document->find('a')->parents('div.article');
?>

Let's talk about a filtration. We have a filter and not methods. The filter method selects elements which matched by query, and the not method is contrary to it.

<?php
// Find DIV elements and filter which class=article
$document->find('div')->filter('.article');
// Find A elements and remove which href=baigudin.software
$document->find('a')->not('a[href=baigudin.software]');
?>

In the conclusion, we should say that all find, parents, filter, not methods return ElementList or ElementNode class objects which inherit the Element interface.

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