Show the differences between 2 xml files (with php

Question

i have an xml file with the following structure.

    <?xml version="1.0" encoding="utf-8"?>
<products>
  <product>
    <nr>0</nr>
    <product_id>17856</product_id>
    <product_number>54586</product_number>
    <product_name>just an name</product_name>
    <product_url>product url</product_url>
    <price>66.3445</price>
    <description> bla die bla </description>
    <manufacturer>manu 1</manufacturer>
    <category>category 1</category>
    <stock>3</stock>
    <eancode></eancode>
    <date_added>2011-04-18 12:10:28</date_added>
    <image_front></image_front>
    <image_back></image_back>
    <vat_value>1.19</vat_value>
  </product>
</products>

The xml file has about 1000 products.

What i would like to achieve is that when i download an new xml PHP code should check which products have changed values of the price an stock.

I have an array recursive method which show the differences between the xml files. But it only shows the xml nodes, i.e. if the stock have been changed i only see the stock in the array.

i use the following function to show the differences.

public function checkFile($file){

            $xml = simplexml_load_file("./var/import/".$file); //nieuw
            $xml1 = $this->simplexml2array($xml);

            $xmls = simplexml_load_file("./var/import/oud/".$file); //oud
            $xml2 =$this->simplexml2array($xmls);


        $checkdiff = $this->arrayRecursiveDiff($xml2, $xml1); 

        if ($checkdiff == NULL){


        return false;
        }else{


        return true;
        }





        }

    public  function arrayRecursiveDiff($aArray1, $aArray2) {
    $aReturn = array();

    foreach ($aArray1 as $mKey => $mValue) {
        if (array_key_exists($mKey, $aArray2)) {
            if (is_array($mValue)) {
                $aRecursiveDiff = $this->arrayRecursiveDiff($mValue, $aArray2[$mKey]);
                if (count($aRecursiveDiff)) { $aReturn[$mKey] = $aRecursiveDiff; }
            } else {
                if ($mValue != $aArray2[$mKey]) {
                    $aReturn[$mKey] = $mValue;
                }
            }
        } else {
            $aReturn[$mKey] = $mValue;
        }
    }

    return $aReturn;
} 

function simplexml2array($xml) {
    if (get_class($xml) == 'SimpleXMLElement') {
        $attributes = $xml->attributes();
        foreach($attributes as $k=>$v) {
            if ($v) $a[$k] = (string) $v;
        }
        $x = $xml;
        $xml = get_object_vars($xml);
    }
    if (is_array($xml)) {
        if (count($xml) == 0) return (string) $x; // for CDATA
        foreach($xml as $key=>$value) {
            $r[$key] = $this->simplexml2array($value);
        }
        if (isset($a)) $r['@attributes'] = $a;    // Attributes
        return $r;
    }
    return (string) $xml;
}

can anybody help me not to only show the the difference field of the xml but the whole xml product information which have been changed.

thank you all in advance.

Answer 1

The following code will

• find and display the outerXML of product elements
• that have the same product_id
• but differ in either price or stock.

It works by iterating all product elements in the old XML, collecting their product_id, price and stock values and assemble them into an XPath query that is then run against the new document.

With DOM

$oldXml = new DOMDocument;
$oldXml->loadXml($old);
$query = array();
foreach ($oldXml->getElementsByTagName('product') as $product) {
    $query[] = sprintf(
        '(product_id = %s and (price != "%s" or stock != "%s"))',
        $product->getElementsByTagName('product_id')->item(0)->nodeValue,
        $product->getElementsByTagName('price')->item(0)->nodeValue,
        $product->getElementsByTagName('stock')->item(0)->nodeValue
    );
}
$query = implode('or', $query);

$newXml = new DOMDocument;
$newXml->loadXml($new);
$xp = new DOMXPath($newXml);
foreach ($xp->query(sprintf('/products/product[%s]', $query)) as $product) {
    echo $newXml->saveXml($product);
}

With SimpleXml

$oldXml = simplexml_load_string($old);
$query = array();
foreach ($oldXml->product as $product) {
    $query[] = sprintf(
        '(product_id = %s and (price != "%s" or stock != "%s"))',
        $product->product_id,
        $product->price,
        $product->stock
    );
}
$query = implode('or', $query);

$newXml = simplexml_load_string($new);
foreach ($newXml->xpath(sprintf('/products/product[%s]', $query)) as $product) {
    echo $product->asXml();
}

Note that this will not find any product elements that have been added or removed in the new document. You didnt mention that as a requirement in your question. If you need this as well, the easiest would be to write two additional queries for that. One comparing the product_id elements from the old document with the new doc and one doing the same from the new doc to the old.

Answer 2

Try this diff algorithm:

function diff($old, $new){
    foreach($old as $oindex => $ovalue){
        $nkeys = array_keys($new, $ovalue);
        foreach($nkeys as $nindex){
            $matrix[$oindex][$nindex] = isset($matrix[$oindex - 1][$nindex - 1]) ?
                $matrix[$oindex - 1][$nindex - 1] + 1 : 1;
            if($matrix[$oindex][$nindex] > $maxlen){
                $maxlen = $matrix[$oindex][$nindex];
                $omax = $oindex + 1 - $maxlen;
                $nmax = $nindex + 1 - $maxlen;
            }
        }   
    }
    if($maxlen == 0) return array(array('d'=>$old, 'i'=>$new));
    return array_merge(
        diff(array_slice($old, 0, $omax), array_slice($new, 0, $nmax)),
        array_slice($new, $nmax, $maxlen),
        diff(array_slice($old, $omax + $maxlen), array_slice($new, $nmax + $maxlen)));
}

// Wrapper for diff - nicer output
function htmlDiff($old, $new){
    $diff = diff(explode(' ', $old), explode(' ', $new));
    foreach($diff as $k){
        if(is_array($k))
            $ret .= (!empty($k['d'])?"<del>".implode(' ',$k['d'])."</del> ":'').
                (!empty($k['i'])?"<ins>".implode(' ',$k['i'])."</ins> ":'');
        else $ret .= $k . ' ';
    }
    return $ret;
}

https://github.com/paulgb/simplediff/blob/5bfe1d2a8f967c7901ace50f04ac2d9308ed3169/simplediff.php