How to snag highest numbered XML item with PHP? - php

Question

I've basically got an XML file full of product information for use in an ecommerce system. I've been creating a script that converts these XML files into a .CSV with the data structured in a format the ecommerce system can handle (So I don't need to copy/paste columns over every time the vendor provides new XML files). The category of each product is defined like this:
<web_category1>3</web_category1>
<web_category2>1</web_category2>
<web_category3>6</web_category3>
web_category3 being the category of the item and 1 and 2 being the parent categories of the product's category. The thing is that some items are nested under 2 categories..or sometimes 5. So I need to figure out a way for PHP to grab the web_category with the highest number after it since that's always going to be the product's category.
Thanks!

Answer 1

#ben's answer is correct, but is a little intense for me. SimpleXMLElement objects are nice because you can easily cast them to an array. So, a simpler solution would be to cast it to an array and use max to determine the highest value in the resulting array:
$str = '
<item>
<web_category1>3</web_category1>
<web_category2>1</web_category2>
<web_category3>6</web_category3>
</item>
';
$xml = new SimpleXMLElement($str);
echo max((array)$xml); // outputs: 6
UPDATE
Based on your comment below, let's assume you need to get the max of all the <item> elements that occur in an XML file and not just one (like above). To handle this you could use SimpleXMLElement::xpathdocs to get an array of all the occurrences of <item> then execute the same casting trick inside a loop over the xpath result:
$str = '
<xml>
<product1>
<item>
<web_category1>3</web_category1>
<web_category2>1</web_category2>
<web_category3>6</web_category3>
</item>
</product1>
<product2>
<item>
<web_category4>17</web_category4>
<web_category5>0</web_category5>
</item>
</product2>
</xml>
';
$xml = new SimpleXMLElement($str);
$allItems = array();
$items = $xml->xpath('//item');
foreach($items as $item) {
$allItems = array_merge($allItems, (array)$item);
}
echo max($allItems); // outputs: 17
UPDATE 2
Okay, last time. If this isn't exactly what you're trying to do, you should at least have enough examples to figure it out from here. Consider:
$str = '
<xml>
<product1>
<web_category1>3</web_category1>
<web_category2>1</web_category2>
<web_category3>6</web_category3>
</product1>
<product2>
<web_category4>17</web_category4>
<web_category5>0</web_category5>
</product2>
<product3>
<web_category6>17</web_category6>
<web_category7>21</web_category7>
</product3>
</xml>
';
$xml = new SimpleXMLElement($str);
// assumes that product node names start with "product"
$products = $xml->xpath("//*[starts-with(name(),'product')]");
foreach ($products as $p) {
$catNames = array_keys((array)$p);
$catNums = preg_replace("/[^\d]/", "", $catNames);
echo $p->getName() . ' - highest category: ' . max($catNums) . "\n";
}
The above code outputs the following:
product1 - highest category: 3
product2 - highest category: 5
product3 - highest category: 7

Answer 2

assuming your XML is something like this:
<item>
<web_category1>3</web_category1>
<web_category2>1</web_category2>
<web_category3>6</web_category3>
</item>
And you have a SimpleXMLElement object for <item>, this should do it:
$highest_web_category_number = -1;
$value_of_highest_web_category_number = -1;
foreach($item->getChildren() as $name => $data) {
if(strpos($name, 'web_category') === 0) {
$web_category_number = substr($name, strlen('web_category'));
if($web_category_number > $highest_web_category_number) {
$highest_web_category_number = $web_category_number
$value_of_highest_web_category_number = $data;
}
}
}