DOM XPath queries fails

Question

I have this code sample (full code here):

$raw = " ( xml data ) ";

$nsURIs = array
(
  'opf'     => 'http://www.idpf.org/2007/opf',
  'dc'      => 'http://purl.org/dc/elements/1.1/',
  'dcterms' => 'http://purl.org/dc/terms/',
  'xsi'     => 'http://www.w3.org/2001/XMLSchema-instance',
  'ncx'     => 'http://www.daisy.org/z3986/2005/ncx/',
  'calibre' => 'http://calibre.kovidgoyal.net/2009/metadata'
);

$dom   = new \DOMDocument();
$dom->loadXML( $raw,LIBXML_NOBLANKS );

$metadata = $dom->getElementsByTagName( 'metadata' )->item(0);         #metadata

$xpath = new \DOMXPath( $dom );
foreach( $nsURIs as $key => $ns ) $xpath->registerNamespace( $key, $ns );

$query = array();
$query[] = '//dc:identifier';                                          #00
$query[] = '//dc:identifier[. = "9780439554930"]';                     #01
$query[] = '//dc:identifier[@opf:scheme="ISBN"]';                      #02
$query[] = '//dc:identifier[starts-with(@opf:scheme,"I")]';            #03
$query[] = '//dc:identifier[contains(@opf:scheme,"SB")]';              #04
$query[] = '//dc:identifier[ends-with(@opf:scheme,"N")]';              #05 Unregistered
$query[] = '//dc:identifier["IS" = substring(@opf:scheme, 0, 2)]';     #06 Fails
$query[] = '//dc:identifier[contains(.,"439")]';                       #07
$query[] = '//dc:identifier[@*="ISBN"]';                               #08
$query[] = '//dc:date[contains(@*, "cation")]';                        #09
$query[] = '//dc:*[contains(@opf:*, "and")]';                          #10 Wrong Result
$query[] = '//dc:*[contains(@opf:file-as, "and")]';                    #11
$query[] = '//dc:*[contains(@opf:*, "ill")]';                          #12
$query[] = '//dc:contributor[@opf:role and @opf:file-as]';             #13
$query[] = '//dc:subject[contains(.,"anta") and contains(.,"Urban")]'; #14
$query[] = '//dc:subject[text() = "Fantasy"]';                         #15

for( $i=0; $i<count($query); $i++ )
{
  $result = $xpath->evaluate( $query[$i] );
  echo sprintf( "[%02d]  % 2d  %s\n", $i, $result->length, $query[$i] );
}

Query #5 Fails due to unregistered function; query #6 Fails (0 results insted of 1) and query #10 generate 1 item instead of 2 (as properly generated at following query #11). Same results performing query on $metadatacontext.

In this question I have found an alternative to unregistered ends-with:

$query[] = '//dc:identifier["N" = substring(@opf:scheme, string-length(@opf:scheme) - string-length("N"))]';

but even this hack fails...

Anyone have suggestion or alternatives?

What is the question exactly? What are you trying to achieve? — har07
– har07, Commented Jan 19, 2016 at 3:46
My achieve is to check if XPath works fine. The question is: fails in provided code are XPath bugs or because of my errors? In xml code there are two nodes with text 'and' in attribute named opf:file-as: why query 10 return 1 item (incorrect) and query #11 return 2 items (ok)? And the hack to bypass unregistered ends-with function (marked as working in cited question) is not correct? Or I have to forget ends-with queries? I'm sorry if I was not clear. — fusion3k
– fusion3k, Commented Jan 20, 2016 at 0:58
regarding ends-with() function, you should've read this (answer to the duplicated question you linked to) — har07
– har07, Commented Jan 20, 2016 at 1:39
Yes, I had read (and linked too)... but I have forget the + 1 at the end! Thanks! (The problem with query #10 remains unsolved). — fusion3k
– fusion3k, Commented Jan 20, 2016 at 1:51
Side notes: 1. XPath expressions that doesn't pose a problem is only distracting the reader, I'd suggest to remove it form your question. 2. Multiple questions is normally better posted separately : meta.stackexchange.com/questions/39223/… (consider these in your future questions). — har07
– har07, Commented Jan 20, 2016 at 2:08

har07 · Accepted Answer · 2016-01-20 02:25:02Z

1

Regarding #06 Fails :

//dc:identifier["IS" = substring(@opf:scheme, 0, 2)]

Explanation :

XPath index start from 1 instead of 0, so the correct parameters of subsstring() here would be :

//dc:identifier["IS" = substring(@opf:scheme, 1, 2)]

Regarding #10 Wrong Result :

//dc:*[contains(@opf:*, "and")]

Explanation :

When passing multiple values as function parameter in XPath 1.0, only the first value would be evaluated. So in this case, only the first attribute with prefix opf will be evaluated, hence the following element doesn't count :

<dc:contributor opf:role="ill" opf:file-as="GrandPré, Mary">Mary GrandPré</dc:contributor>

to avoid this problem, you should change the XPath to be as follow :

//dc:*[@opf:*[contains(., "and")]]

edited Jan 20, 2016 at 2:25

answered Jan 20, 2016 at 2:07

har07

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