使用Xpath和PHP获取XML父/祖先的价值？

Question

Let's say I have this XML:

<Routes>
  <Route ref="timeconditions">
   <Table>
     <Tablename>timeconditions</Tablename>
     <Fields>
       <Fieldsname>truegoto</Fieldsname>
     </Fields>
   </Table>
  </Route>
</Routes>

PHP:

$doc    = new SimpleXMLElement('routingConfig.xml', null, true);
$foo = $doc->xpath('/Routes/Route[@ref="timeconditions"]/Table/Fields[@Fieldsname="truegoto"]/ancestor::Tablename');
print_r($foo);

Returns blank array. Now I realize I'm basically digging into a child then backing up to it's parent, but in my context that is what I need to do. What am I doing wrong? I'm trying to get <Fieldsname>falsegoto</Fieldsname> parents sibling value called <Tablename>.

Going crosseyed staring at this....

Answer 1

Fields has no attribute Fieldsname its a child node, also Tablename is a sibling of Fields not an ancestor. Try

$foo = $doc->xpath('/Routes/Route[@ref="timeconditions"]/Table/Fields[Fieldsname="truegoto"]/preceding-sibling::Tablename');