Getting data from XML - php

Question

I am struggling with reading XML file using PHP.
The XML I want to use is here:
http://www.gdacs.org/xml/rss.xml
Now, the data I am interested are the "item" nodes.
I created the following function, which gets the data:
$rawData = simplexml_load_string($response_xml_data);
foreach($rawData->channel->item as $value) {
$title = $value->title;
....
this works fine.
The nodes with the "gdcs:xxxx" were slightly more problematic, but I used the following code, which also works:
$subject = $value->children('dc', true)->subject;
Now the problem I have is with the "resources" node,
Basically the stripped down version of it would look like this:
<channel>
<item>
<gdacs:resources>
<gdacs:resource id="xx" version="0" source="xx" url="xx" type="xx">
<gdacs:title>xxx</gdacs:title>
</gdacs:resource>
<gdacs:resource id="xx" version="0" source="xx" url="xx" type="xx">
<gdacs:title>xxx</gdacs:title>
</gdacs:resource>
<gdacs:resource id="xx" version="0" source="xx" url="xx" type="xx">
<gdacs:title>xxx</gdacs:title>
</gdacs:resource>
</gdacs:resources>
</item>
</channel>
How in this case would I get the resources? I was able to get always just the first resource and only the title of it. What I would like to do is get all the resources items, which have "type" of a particular value and get their URL.

Answer 1

Running through XML the regular path, is , from my experience, slow and excruciating.
Have a look into XPath -> it's a way to extract data from XML through selectors ( similar to CSS selectors )
http://php.net/manual/en/simplexmlelement.xpath.php
You can select elements by their attributes similar to CSS
<?php
$xmlStr = file_get_contents('some_xml.xml');
$xml = new SimpleXMLElement($xmlStr);
$items = $xml->xpath("//channel/item");
$urls_by_item = array();
foreach($items as $x) {
$urls_by_item [] = $x->xpath("//gdacs:resources/gdacs:resource[#type='image']/#url");
}

Answer 2

Consider using the node occurrence of xpath with square brackets [] to align urls with corresponding titles. A more involved modification of #Daniel Batkilin's answer, you can incorporate both data pieces in an associative multidimensional array, requiring nested for loops.
$xml = simplexml_load_file('http://www.gdacs.org/xml/rss.xml');
$xml->registerXPathNamespace('gdacs', 'http://www.gdacs.org');
$items = $xml->xpath("//channel/item");
$i = 1;
$out = array();
foreach($items as $x) {
$titles = $xml->xpath("//channel/item[".$i."]/gdacs:resources/gdacs:resource[#type='image']/gdacs:title");
$urls = $xml->xpath("//channel/item[".$i."]/gdacs:resources/gdacs:resource[#type='image']/#url");
for($j=0; $j<count($urls); $j++) {
$out[$j.$i]['title'] = (string)$titles[$j];
$out[$j.$i]['url'] = (string)$urls[$j];
}
$i++;
}
$out = array_values($out);
var_dump($out);
ARRAY DUMP
array(40) {
[0]=>
array(2) {
["title"]=>
string(21) "Storm surge animation"
["url"]=>
string(92) "http://webcritech.jrc.ec.europa.eu/ModellingCyclone/cyclonesurgeVM/1000226/final/outres1.gif"
}
[1]=>
array(2) {
["title"]=>
string(26) "Storm surge maximum height"
["url"]=>
string(101) "http://webcritech.jrc.ec.europa.eu/ModellingCyclone/cyclonesurgeVM/1000226/final/P1_MAXHEIGHT_END.jpg"
}
[2]=>
array(2) {
["title"]=>
string(12) "Overview map"
["url"]=>
string(64) "http://dma.gdacs.org/saved/gdacs/tc/1000226/clouds_1000226_2.png"
}
[3]=>
array(2) {
["title"]=>
string(41) "Map of rainfall accummulation in past 24h"
["url"]=>
string(70) "http://dma.gdacs.org/saved/gdacs/tc/1000226/current_rain_1000226_2.png"
}
[4]=>
array(2) {
["title"]=>
string(23) "Map of extreme rainfall"
["url"]=>
string(62) "http://dma.gdacs.org/saved/gdacs/tc/1000226/rain_1000226_2.png"
}
[5]=>
array(2) {
["title"]=>
string(34) "Map of extreme rainfall (original)"
["url"]=>
string(97) "http://www.ssd.noaa.gov/PS/TROP/DATA/ETRAP/2015/NorthIndian/THREE/2015THREE.pmqpf.10100000.00.GIF"
}
...