Multiple values in one attribute (such as class) in simplexml (using PHP)

Question

If I try to add the same attribute twice to an element via simplexml, I get the following error:

Warning: SimpleXMLElement::addAttribute() [function.SimpleXMLElement-addAttribute]: Attribute already exists...

As a workaround, I'm using if-else statements for the three possibilities:

if ($a && $b) {
    $node -> addAttribute("class", "a b");
 }
 else if($a) {
    $node -> addAttribute("class", "a");
 }
 else if ($b) {
    $node -> addAttribute("class", "b");
 }

But that feels a bit clunky,and not very scalable. Is there a better way anyone is using?

Answer 1

Hi,

Instead of using SimpleXMLElement::addAttribute, maybe you can just use array-access to the parameters ?

For instance, considering you have that portion of code :

$str = <<<XML
<root>
    <elem>glop</elem>
</root>
XML;

$xml = simplexml_load_string($str);
var_dump($xml->elem);

Which gives this output :

object(SimpleXMLElement)[2]
  string 'glop' (length=4)

You can add the "class=a" attribute this way :

$xml->elem['class'] .= 'a ';
var_dump($xml->elem);

Which will give you this output :

object(SimpleXMLElement)[5]
  public '@attributes' => 
    array
      'class' => string 'a ' (length=2)
  string 'glop' (length=4)

And, then, add the "class=b" attribute by concatenating that value to the existing value of class, this way :

$xml->elem['class'] .= 'b ';
var_dump($xml->elem);

And you obtain :

object(SimpleXMLElement)[7]
  public '@attributes' => 
    array
      'class' => string 'a b ' (length=4)
  string 'glop' (length=4)

Note the space at the end of the attribute's value ; maybe you'll want to clean this, using trim :

$xml->elem['class'] = trim($xml->elem['class']);
var_dump($xml->elem);

Et voila :

object(SimpleXMLElement)[8]
  public '@attributes' => 
    array
      'class' => string 'a b' (length=3)
  string 'glop' (length=4)

Hope this helps :-)