This class is extendable, but it's too bad that its constructor cannot be overriden (PHP says it's a final method). Thus the class should be wrapped using the delegation principle rather that extended.
(PHP 5, PHP 7)
SimpleXMLElement::__construct — Crée un nouvel objet SimpleXMLElement
$data
[, int $options
= 0
[, bool $data_is_url
= FALSE
[, string $ns
= ""
[, bool $is_prefix
= FALSE
]]]] )Crée un nouvel objet SimpleXMLElement.
data
Une chaîne de caractères XML bien formée ou le chemin d'accès ou un
URL pointant à un document XML si data_is_url
vaut TRUE
.
options
Optionnellement utilisé pour spécifier des paramètres Libxml additionnels.
Note:
Il peut être nécessaire de passer
LIBXML_PARSEHUGE
pour pouvoir traiter des nœuds de texte profondément imbriqués ou très volumineux.
data_is_url
Par défaut, data_is_url
vaut FALSE
. Utilisez
TRUE
pour spécifier que le paramètre data
est
un chemin d'accès ou un URL pointant à un document XML au lieu d'une
chaîne de caractères de données.
ns
Préfixe d'espace de noms ou URI.
is_prefix
TRUE
si ns
est un préfix, FALSE
sinon.
Valeur par défaut : FALSE
.
Retourne un objet SimpleXMLElement représentant les données
data
.
Produit un message d'erreur de type E_WARNING
pour chaque erreur trouvée dans les données XML et
lance également une exception si les données XML ne peuvent re
analysées.
Utilisez la fonction libxml_use_internal_errors() pour supprimer toutes les erreurs XML et la fonction libxml_get_errors() pour les parcourir.
Note:
Les exemples listés incluent parfois example.php, ceci fait référence à la chaine XML du premier exemple de l'utilisation de base.
Exemple #1 Crée un objet SimpleXMLElement
<?php
include 'example.php';
$sxe = new SimpleXMLElement($xmlstr);
echo $sxe->movie[0]->title;
?>
L'exemple ci-dessus va afficher :
PHP: Behind the Parser
Exemple #2 Crée un objet SimpleXMLElement à partir d'un URL
<?php
$sxe = new SimpleXMLElement('http://example.org/document.xml', NULL, TRUE);
echo $sxe->asXML();
?>
Version | Description |
---|---|
5.2.0 | Ajout des paramètres ns et
is_prefix . |
5.1.2 | Ajout des paramètres options et
data_is_url . |
This class is extendable, but it's too bad that its constructor cannot be overriden (PHP says it's a final method). Thus the class should be wrapped using the delegation principle rather that extended.
The manual doesn't really explain what the $ns argument (and the accompanying $is_prefix) are for.
What they do is similar to the ->children() method: they set the context of the returned object to that namespace, so that access via ->elementName and ['attributeName'] refer to elements and attributes in that namespace.
In particular, they do *not* change the namespaces which exist on the document.
See this example:
<?php
// This XML contains two elements called <child>
// One is in the namespace http://example.com, with local prefix 'ws'
// The other has no namespace (no prefix, and no default namespace declared)
$xml = '<ws:example xmlns:ws="http://example.com"><child>Not in namespace</child><ws:child>In example namespace</ws:child></ws:example>';
$sx0 = new SimpleXMLElement($xml, 0, false);
$sx1 = new SimpleXMLElement($xml, 0, false, 'http://example.com');
$sx2 = new SimpleXMLElement($xml, 0, false, 'ws', true);
echo "
Without: {$sx0->child}
By namespace: {$sx1->child}
By prefix: {$sx2->child}
";
?>
Output:
Without: Not in namespace
By namespace: In example namespace
By prefix: In example namespace
Using libxml_use_internal_errors() may suppress errors but Exception still requires decent handling. I used following code snippet.
<?php
libxml_use_internal_errors(true);
try{
$xmlToObject = new SimpleXMLElement($notSoWellFormedXML);
} catch (Exception $e){
echo 'Please try again later...';
exit();
}
?>
You won't be able to load an XML file without root element:
//This will throw an exception
$xml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?>', null, false);
//Here is the solution
$xml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><root></root>', null, false);
It's worth noting that the behavior of SimpleXmlElement::__construct is not exactly the same as simplexml_load_string, regarding libxml_use_internal_errors().
In my case,
<?php
libxml_use_internal_errors(true);
new \SimpleXmlElement($data);
?>
was still throwing error. But as soon as I switched to
<?php
libxml_use_internal_errors(true);
simplexml_load_string($data);
?>
everything worked fine and I stopped getting an error.
It's worth noting, that you need to typecast dynamic property names to string in order to retrieve there value, for example:
<?php
$xml = new SimpleXMLElement('records.xml', 0, true);
// This will work as expected because its a hard coded property value
foreach($xml as $record){
echo $record->id; // Will output the ID fine
}
// Dynamic properties require typecasting to string
$xml_field = 'id';
foreach($xml as $record){
// This will dump a SimpleXMLElement object
var_dump($record->$xml_field);
// This will output the value as expected
echo (string)$record->$xml_field;
}
?>
As I was filling out a bug report, I realized why (speculation here) the constructor is final: so that functions like simplexml_load_file and simplexml_load_string can work. I imagine the PHP-ized code looks something like
<?php
function simplexml_load_file($filename, $class_name = "SimpleXMLElement", $options = 0, $ns = "", $is_prefix = false) {
return new $class_name($filename, $options, true, $ns, $is_prefix);
}
?>
If we were to use a different $class_name and change the constructor's definition these functions wouldn't work.
There's no easy, sensible solution that keeps simplexml_load_file and simplexml_load_string.