Retrieve book data from the LibraryThing Common Knowledge API.

librarything.php

<?php

namespace ocra\libraryThing;

/**
 * Search LibraryThing's Common Knowledge API for a book and return and array with author/title and maybe year.
 */
function find_by_isbn($isbn) {
    $lturl = 'http://www.librarything.com/services/rest/1.1/?method=librarything.ck.getwork&isbn=%s&apikey=%s';
    $lturl = sprintf($lturl, $isbn, LIBRARYTHING_API_KEY);
    
    $ckdata = file_get_contents($lturl);
    //Librarything sometimes sends less-than-well-formed XML.
    
    $ckdata = str_replace('&lt;![CDATA[', '<![CDATA[', $ckdata);
    $ckdata = str_replace(']]&gt;', ']]>', $ckdata);
    $ckdata = str_replace('&nbsp;', ' ', $ckdata);
    
    $tidy = new \Tidy;
    $tidyconf = array(
                      'input-xml' =>        true,
                      'output-xml' =>       true,
                      'escape-cdata' =>     true,
                      'add-xml-decl' =>     true,
                      'preserve-entities' => true,
                      'doctype' =>          'omit',
                      'quote-nbsp' =>       true,
                      'hide-comments' =>    true,
                      'wrap' =>             0,
                      );
    $ckdata = $tidy->repairString($ckdata, $tidyconf, 'utf8');
    $ckdata = $tidy->repairString($ckdata, $tidyconf, 'utf8');
    
    $origerr = libxml_use_internal_errors(true);
    $ckdata = new \SimpleXMLElement( $ckdata );
    libxml_use_internal_errors($origerr);
    
    if ( @$ckdata->ltml ) {
        $ckdata->registerXPathNamespace('lt', 'http://www.librarything.com/');
        $date = $ckdata->xpath('//lt:commonknowledge/lt:fieldList/lt:field[@name="originalpublicationdate"]//lt:fact');
        
        if ( $date ) {
            $year = @date('Y', strtotime((string)$date[0]));
        }
        
        $author = (string)$ckdata->ltml->item->author;
        $title = (string)$ckdata->ltml->item->title;
        
        $book = compact('author', 'title', 'year');
        return $book;
    }
    return false;
}