PHP/XPath: Iterating through ancestor nodes in XML using SimpleXML

Question

I need to loop through the Ancestors nodes in order to get corresponding BrowseNodeId and Name values. How do I do this using XPath? I'm trying something like the the following, but it's not working:

//BrowseNode[1]//Ancestors[1]/BrowseNode/BrowseNodeId/text()
//BrowseNode[1]//Ancestors[1]/BrowseNode/Name/text()

I think the //Ancestors part of the XPath is actually searching the entire XML tree. What I need to do is visit each node to get the needed values. How do I do this? In the example below, I want: Europe -> History -> Subjects -> Books.

Example XML:

    <BrowseNode>
        <BrowseNodeId>4952</BrowseNodeId>
        <Name>France</Name>
        <Ancestors>
            <BrowseNode>
                <BrowseNodeId>4935</BrowseNodeId>
                <Name>Europe</Name>
                <Ancestors>
                    <BrowseNode>
                        <BrowseNodeId>9</BrowseNodeId>
                        <Name>History</Name>
                        <Ancestors>
                            <BrowseNode>
                                <BrowseNodeId>1000</BrowseNodeId>
                                <Name>Subjects</Name>
                                <IsCategoryRoot>1</IsCategoryRoot>
                                <Ancestors>
                                    <BrowseNode>
                                        <BrowseNodeId>283155</BrowseNodeId>
                                        <Name>Books</Name>
                                    </BrowseNode>
                                </Ancestors>
                            </BrowseNode>
                        </Ancestors>
                    </BrowseNode>
                </Ancestors>
            </BrowseNode>
        </Ancestors>
    </BrowseNode>

@Alejandro 's answer is better than the one you have accepted. The accepted answer is in fact wrong, because doesnt obtain any node at all: the XPath expression /Ancestors/BrowseNode doesn't select any node because your XML document doesn't have a top element named Ancestors. Please, consider accepting a correct answer, because accepting a wrong answer may mislead other people. — Dimitre Novatchev
– Dimitre Novatchev, Commented Jan 8, 2011 at 17:10

user357812 · Accepted Answer · 2011-01-08 13:35:06Z

1

In the example below, I want: Europe -> History -> Subjects -> Books.

I think you need:

//Ancestors/BrowseNode/Name

Or just iterate over //Ancestors/BrowseNode results and get the Name and BrowseNodeId children with any DOM method.

answered Jan 8, 2011 at 13:35

user357812

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Comments

dqhendricks · Accepted Answer · 2011-01-08 18:49:06Z

0

$browse_nodes = $xml->BrowseNode;
foreach ($browse_nodes as $browse_node) {
    echo $browse_node->BrowseNodeId.nodeValue;
    echo $browse_node->Name.nodeValue;
}

edited Jan 8, 2011 at 18:49

answered Jan 8, 2011 at 6:56

dqhendricks

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3 Comments

StackOverflowNewbie Over a year ago

I don't think this works. The XML I have is huge, and has a lot of the top level BrowseNode elements. Also, I am only interested in the Ancestors/BrowseNode of each top level BrowseNode element. Meaning, I need something like this: //BrowseNode[1]/Ancestors/BrowseNode, then //BrowseNode[2]/Ancestors/BrowseNode, then //BrowseNode[3]/Ancestors/BrowseNode ... The problem is that the // is searching the entire tree, I think. What I need is to walk the sub-tree of each top level BrowseNode

dqhendricks Over a year ago

oic, maybe try single slash xpath('/Ancestors/BrowseNode'), then xpath('/Ancestors/BrowseNode/Ancestors/BrowseNode'), etc.

dqhendricks Over a year ago

probably don't need xpath for this. you cn iterate through a set of children like you would an array.

Xavier Barbosa · Accepted Answer · 2011-01-08 08:34:41Z

Maybe try to locate the final node, then extract is ancestors ?

<?php

$xml = "
    <BrowseNode>
        <BrowseNodeId>4952</BrowseNodeId>
        <Name>France</Name>
        <Ancestors>
            <BrowseNode>
                <BrowseNodeId>4935</BrowseNodeId>
                <Name>Europe</Name>
                <Ancestors>
                    <BrowseNode>
                        <BrowseNodeId>9</BrowseNodeId>
                        <Name>History</Name>
                        <Ancestors>
                            <BrowseNode>
                                <BrowseNodeId>1000</BrowseNodeId>
                                <Name>Subjects</Name>
                                <IsCategoryRoot>1</IsCategoryRoot>
                                <Ancestors>
                                    <BrowseNode>
                                        <BrowseNodeId>283155</BrowseNodeId>
                                        <Name>Books</Name>
                                    </BrowseNode>
                                </Ancestors>
                            </BrowseNode>
                        </Ancestors>
                    </BrowseNode>
                </Ancestors>
            </BrowseNode>
        </Ancestors>
    </BrowseNode>
";


$sxe = simplexml_load_string($xml);

// Set the target to reach
$target = current($sxe->xpath("//BrowseNode[./BrowseNodeId = '283155']"));

// Get all names from root to target
$names = array_map('strval', $target->xpath('ancestor-or-self::Ancestors/BrowseNode/Name'));
print_r($names);
// Array
// (
//     [0] => Europe
//     [1] => History
//     [2] => Subjects
//     [3] => Books
// )

// Get all ids from root to target
$ids = array_map('strval', $target->xpath('ancestor-or-self::Ancestors/BrowseNode/BrowseNodeId'));
print_r($ids);
// Array
// (
//     [0] => 4935
//     [1] => 9
//     [2] => 1000
//     [3] => 283155
// )

// Final
$combined = array_combine($ids, $names);
print_r($combined);
// Array
// (
//     [4935] => Europe
//     [9] => History
//     [1000] => Subjects
//     [283155] => Books
// )

Flack · Accepted Answer · 2011-01-08 13:36:58Z

0

/BrowseNode/Ancestors//BrowseNode/Name/text()

Will work with you sample.

However, it will search all nodes descandant to the "first" Ancestors element. Reversing and looking from the deepest BrowseNode would do pretty much the same.

In XSLT the viable and necessary alternative would be using keys for better efficiency.

answered Jan 8, 2011 at 13:36

Flack

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Comments

salathe · Accepted Answer · 2011-01-08 17:12:10Z

0

I may have misunderstood your description of precisely what you want, but hopefully not. This snippet looks for all of the "top level" BrowseNode elements and loops over them, getting their associated ancestor BrowseNode elements each time.

// Get top level BrowseNode elements
$browse_nodes = $xml->xpath('//BrowseNodes/BrowseNode');
foreach ($browse_nodes as $browse_node) {
    // Get ancestor BrowseNode elements
    $ancestors = $browse_node->xpath('Ancestors//BrowseNode');
    // Do whatever you like with them! :-)
}

answered Jan 8, 2011 at 17:12

salathe

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