simplexml

[tonymc]

I'm trying to access elements within a xml file using PHP simplexml_load_string(). Here's a snippet of the xml:

• <collection>
• <record xmlns="http://www.loc.gov/MARC21/slim">
  <leader>01001cam a2200313 a 4500</leader>
  <controlfield tag="001">102514</controlfield>
  <controlfield tag="005">20050830103940.0</controlfield>
  <controlfield tag="008">030315s1990 nyua j 000 0 eng d</controlfield>
• <datafield tag="010" ind1="" ind2="">
  <subfield code="a">94127114</subfield>
  </datafield>

I can access "leader" with:

print $xml->leader;

However, for the other elements I'm not sure what correct syntax is.... For instance, I've tried the following:

print $xml->control field tag="001";

That doesn't work.... Can anybody help me with the correct syntax. I'm a newbie with xml but have worked with PHP for quite a while. Any help is greatly appreciated.

[Weedpacket]

XPath is the easiest way to go for this. I can't figure out exactly what would be appropriate since the fragment you supply isn't well formed, but the simplest (which may or may not be what you want) would be

$xml->xpath('//controlfield/@tag');

[tonymc]

Thank you for the guidance, Weedpacket. This is all very new to me and I'm trying to learn as much as possible from various online tutorials and a couple of books I have. xpath seems like the way to go for my intended use and I appreciate you bringing this function to my attention.

I'm still struggling with the syntax and am wondering if you could look at a more complete xml doc and perhaps get me pointed in the right direction? I have tried the following:

$xml->xpath("//controlfield[@tag='001']");
$xml->xpath("//controlfield/@tag='001'");
$xml->xpath("//controlfield/[@tag='001']");

None of these work and there's nothing in my error logs that sheds any light. BTW -- I'm using PHP 5.0.4. Here's a more complete xml document:

<?xml version="1.0" encoding="UTF-8" ?>
- <record xmlns="http://www.loc.gov/MARC21/slim">
<leader>01001cam a2200313 a 4500</leader>
<controlfield tag="001">102514</controlfield>
<controlfield tag="005">20050830103940.0</controlfield>
<controlfield tag="008">030315s1990 nyua j 000 0 eng d</controlfield>
- <datafield tag="010" ind1="" ind2="">
<subfield code="a">94127114</subfield>
</datafield>
- <datafield tag="035" ind1="" ind2="">
<subfield code="a">(OCoLC)ocm22462806</subfield>
</datafield>
- <datafield tag="040" ind1="" ind2="">
<subfield code="a">KyHhN</subfield>
<subfield code="c">DLC</subfield>
<subfield code="d">PQA</subfield>
</datafield>
- <datafield tag="020" ind1="" ind2="">
<subfield code="a">0941355020</subfield>
</datafield>
- <datafield tag="042" ind1="" ind2="">
<subfield code="a">lccopycat</subfield>
<subfield code="a">lcac</subfield>
</datafield>
- <datafield tag="050" ind1="0" ind2="0">
<subfield code="a">QA95</subfield>
<subfield code="b">.B83 1990</subfield>
</datafield>
- <datafield tag="082" ind1="0" ind2="0">
<subfield code="a">793.7/4</subfield>
<subfield code="2">20</subfield>
</datafield>
- <datafield tag="099" ind1="" ind2="">
<subfield code="a">J</subfield>
<subfield code="a">793.74</subfield>
<subfield code="a">B96</subfield>
</datafield>
- <datafield tag="049" ind1="" ind2="">
<subfield code="a">PQA$</subfield>
</datafield>
- <datafield tag="100" ind1="1" ind2="">
<subfield code="a">Burns, Marilyn,</subfield>
<subfield code="d">1941-</subfield>
</datafield>
- <datafield tag="245" ind1="1" ind2="4">
<subfield code="a">The $1.00 word riddle book /</subfield>
<subfield code="c">riddles by Marilyn Burns ; pictures by Martha Weston.</subfield>
</datafield>
- <datafield tag="260" ind1="" ind2="">
<subfield code="a">[New York?] :</subfield>
<subfield code="b">Math Solutions Publications ;</subfield>
<subfield code="a">White Plains, N.Y. :</subfield>
<subfield code="b">Distributed by Cuisenaire Co. of America,</subfield>
<subfield code="c">c1990.</subfield>
</datafield>
- <datafield tag="300" ind1="" ind2="">
<subfield code="a">48 p. :</subfield>
<subfield code="b">ill. ;</subfield>
<subfield code="c">21 cm.</subfield>
</datafield>
- <datafield tag="650" ind1="" ind2="0">
<subfield code="a">Mathematical recreations.</subfield>
</datafield>
- <datafield tag="650" ind1="" ind2="0">
<subfield code="a">Riddles.</subfield>
</datafield>
- <datafield tag="650" ind1="" ind2="1">
<subfield code="a">Mathematical recreations.</subfield>
</datafield>
- <datafield tag="650" ind1="" ind2="1">
<subfield code="a">Riddles.</subfield>
</datafield>
- <datafield tag="700" ind1="1" ind2="">
<subfield code="a">Weston, Martha,</subfield>
<subfield code="e">ill.</subfield>
</datafield>
- <datafield tag="740" ind1="0" ind2="">
<subfield code="a">One dollar word riddle book.</subfield>
</datafield>
- <datafield tag="948" ind1="" ind2="0">
<subfield code="s">2002-2003 Elementary Education $7.46</subfield>
</datafield>
- <datafield tag="994" ind1="" ind2="">
<subfield code="a">X0</subfield>
<subfield code="b">PQA</subfield>
</datafield>
</record>

[Weedpacket]

The bit that's causing grief is the namespace declaration; default namespaces mean queries involving nodes that aren't prefixed with namespace declarations just won't work. Depressingly idiotic behaviour, but there it is. It's supposed to be fixed in XPath version 2.

But all does not seem to be lost. Have a crack at:

$xml->registerXPathNamespace('c',"http://www.loc.gov/MARC21/slim");

$controlfield_element = $xml->xpath("//c:controlfield[@tag='001']");