xml to hashmap - php

Question

Hi, Given an xml structure like this

<gesmes:Envelope>
<gesmes:subject>Reference rates</gesmes:subject>
<gesmes:Sender>
<gesmes:name>European Central Bank</gesmes:name>
</gesmes:Sender>
<Cube>
<Cube time="2010-03-26">
<Cube currency="USD" rate="1.3353"/>
<Cube currency="JPY" rate="124.00"/>
<Cube currency="BGN" rate="1.9558"/>
<Cube currency="CZK" rate="25.418"/>
...
...
</Cube>
</Cube>
</gesmes:Envelope>

how can i go about getting the values stored in to a hashmap or similar structure in php?

Have been trying to do this for the last few hours now but cant manage it :D

It is homework so i guess no full solutuins please( tho the actual assignment is to use the web services, i am just stuck with parsing it :D ). Maybe someone could show me a brief example for a made up xml file that i could apply to mine?

Thanks

Answer 1

The easiest way is to use the DOMDocument class. For example:

$src = <<<END
<Cube>
<Cube time="2010-03-26">
<Cube currency="USD" rate="1.3353"/>
<Cube currency="JPY" rate="124.00"/>
<Cube currency="BGN" rate="1.9558"/>
<Cube currency="CZK" rate="25.418"/>
</Cube>
</Cube>
END;

$xml = new DOMDocument;
$xml->loadXML($src);
$cubes = $xml->getElementsByTagName('Cube');
$currencies = array();
foreach ($cubes as $cube) {
  $currency = $cube->getAttribute('currency');
  $rate = $cube->getAttribute('rate');
  if ($currency && $rate) {
    $currencies[$currency] = $rate;
  }
}
print_r($currencies);

Output:

Array
(
    [USD] => 1.3353
    [JPY] => 124.00
    [BGN] => 1.9558
    [CZK] => 25.418
)

Answer 2

<gesmes:Envelope> is probably not the "whole truth". A prefix like gesmes: needs to be associated with an uri. In your case it's probably

<gesmes:Envelope
  xmlns:gesmes="http://www.gesmes.org/xml/2002-08-01"
  xmlns="http://www.ecb.int/vocabulary/2002-08-01/eurofxref"
>

And now you have to deal with namespaces....

There is php's simplexml module. It has some shortcomings when namespaces are involved. But anyway... here it is:

$s = new SimpleXMLelement(getData());
foreach( $s->Cube as $cubeContainer) {
  foreach( $cubeContainer as $cubeEntry) {
    echo 'time: ', $cubeEntry['time'], "\n";
    foreach( $cubeEntry->Cube as $cubeElement) {  
      echo '  ', $cubeElement['currency'], '=', $cubeElement['rate'], "\n";
    }
  }
}

// now that was easy ...now the fun of having namespaces/prefixes
foreach( $s->children("http://www.gesmes.org/xml/2002-08-01")->subject as $subject) {
  echo 'subject: ', $subject, "\n";
}

foreach( $s->children("http://www.gesmes.org/xml/2002-08-01")->Sender as $sender) {
  foreach( $sender->children("http://www.gesmes.org/xml/2002-08-01")->name as $name) {
    echo 'sender/name: ', $name, "\n";
  }
}



function getData() {
  return '<gesmes:Envelope xmlns:gesmes="http://www.gesmes.org/xml/2002-08-01" xmlns="http://www.ecb.int/vocabulary/2002-08-01/eurofxref"&gt;
    <gesmes:subject>Reference rates</gesmes:subject>
    <gesmes:Sender>
      <gesmes:name>European Central Bank</gesmes:name>
    </gesmes:Sender>
    <Cube>
      <Cube time="2010-03-26">
        <Cube currency="USD" rate="1.3353"/>
        <Cube currency="JPY" rate="124.00"/>
        <Cube currency="BGN" rate="1.9558"/>
        <Cube currency="CZK" rate="25.418"/>
      </Cube>
    </Cube>
  </gesmes:Envelope>';
}

prints

time: 2010-03-26
  USD=1.3353
  JPY=124.00
  BGN=1.9558
  CZK=25.418
subject: Reference rates
sender/name: European Central Bank

If you want to use XPath to find specific elements/nodes (either SimpleXMLElement::xpath or DOMXPath which you would use with DOMDocument as pointed out by cletus) you have to register the namespace first.

e.g.

$s = new SimpleXMLelement(getData());
$s->registerXPathNamespace('gesmes', 'http://www.gesmes.org/xml/2002-08-01');
foreach($s->xpath('//gesmes:name[position()=1]') as $n){
  echo $n, "\n";
}

prints European Central Bank.

And there are other functions/methods to parse an XML document. E.g. XMLReader or (which is probably the closest to your your original quest "how can i go about getting the values stored in to a hashmap [...]?") xml_parse_into_struct()