如何使用XPath获取节点的值？

Question

How do I get the value of a node with XPath?

Get all nodes which have a price above 35

/bookstore/book[price>35.00]

But when I change the > to an = for equals, the query fails. Please help. By the way I'm using php, but that shouldn't matter as XPath is universal.

Here's the php code and xml code I was using

$xml = "<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>
 <bookstore>
 <book>
   <title lang=\"eng\">Harry Potter</title>
   <price>29.99</price>
 </book>
 <book>
   <title lang=\"eng\">Learning XML</title>
   <price>39.95</price>
 </book>
 </bookstore>"; $xml = new SimpleXMLElement($xml);

    $name = 'Shiny Red';
    $nodes = $xml->xpath(sprintf('/bookstore/book[price>35.00]', $name));
    if (!empty($nodes)) {
        printf('At least one building named "%s" found<hr/>', $name);
    echo "<textarea style=\"width: 400px; height: 300px;\">";print_r($nodes); echo "</textarea>";
    } else {
        printf('No building named "%s" found', $name);
    }    

Answer 1

//bookstore/book/price[. ='35.00']

or

//bookstore/book[price='35.00']

The trick is in the quotes. Node values are text. You won't match anything with '35.00' however, but that is because your XML doesn't contain books with that price. Matching '39.95' will work (tested).

$xml = "<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>
 <bookstore>
 <book>
   <title lang=\"eng\">Harry Potter</title>
   <price>29.99</price>
 </book>
 <book>
   <title lang=\"eng\">Learning XML</title>
   <price>39.95</price>
 </book>
 </bookstore>"; $xml = new SimpleXMLElement($xml);

    $name = 'Shiny Red';
    $nodes = $xml->xpath(sprintf('//bookstore/book/price[. = \'39.95\']', $name));
    if (!empty($nodes)) {
        printf('At least one building named "%s" found<hr/>', $name);
    echo "<textarea style=\"width: 400px; height: 300px;\">";print_r($nodes); echo "</textarea>";
    } else {
        printf('No building named "%s" found', $name);
    }