SimpleXMLElement::__construct

(PHP 5, PHP 7, PHP 8)

SimpleXMLElement::__construct — Crea un nuevo objeto SimpleXMLElement

Descripción

public SimpleXMLElement::__construct(
    string $data,
    int $options = 0,
    bool $dataIsURL = false,
    string $namespaceOrPrefix = "",
    bool $isPrefix = false
)

Crea un nuevo objeto SimpleXMLElement.

Parámetros

data: Un string XML correcto o la ruta o URL a un documento XML si data_is_url es true.
options: Se utiliza opcionalmente para especificar parámetros adicionales de Libxml, que afectan a la lectura de los documentos XML. Las opciones que afectan a la salida de los documentos XML (p.e. LIBXML_NOEMPTYTAG) son silenciosamente ignoradas.

Nota:
Puede ser necesario pasar LIBXML_PARSEHUGE para poder procesar XML profundamente anidados o nodos de texto muy grandes.
data_is_url: Por defecto, data_is_url es false. Usar true para precisar que data es una ruta o URL a un documento XML en vez de un string de datos.
ns: Prefijo de espacio de nombres o URI.
is_prefix: true si ns es un prefijo, false si es una URI; por omisión, false.

Valores devueltos

Retorna un objeto SimpleXMLElement representando data.

Errores/Excepciones

Produce un mensaje de error E_WARNING por cada error encontrado en los datos XML y adicionalmente lanza una Exception si no se han podido analizar correctamente los datos XML.

Sugerencia

Debe usarse libxml_use_internal_errors() para eliminar todos los errores XML y libxml_get_errors() para iterar sobre ellos después.

Historial de cambios

Versión	Descripción
5.2.0	Añadidos los parámetros `ns` y `is_prefix`.
5.1.2	Añadidos los parámetros `options` y `data_is_url`.

Ejemplos

Nota:
Los ejemplos listados quizá incluyen example.php, que hacen referencia a la cadena XML encontrada en el primer ejemplo de la guía de uso básico.

Ejemplo #1 Crea un objeto SimpleXMLElement

<?php

include 'example.php';

$sxe = new SimpleXMLElement($xmlstr);
echo $sxe->pelicula[0]->titulo;

?>

El resultado del ejemplo sería:

PHP: Tras el Parser

Ejemplo #2 Crea un objeto SimpleXMLElement a partir de una URL

<?php

$sxe = new SimpleXMLElement('http://example.org/document.xml', NULL, TRUE);
echo $sxe->asXML();

?>

Ver también

Uso básico de SimpleXML
simplexml_load_string() - Interpreta un string de XML en un objeto
simplexml_load_file() - Interpreta un fichero XML en un objeto
Tratar con los errores XML
libxml_use_internal_errors() - Deshabilita errores libxml y permite al usuario extraer información de errores según sea necesario

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User Contributed Notes 8 notes

down

rowan dot collins at gmail dot com ¶

7 years ago


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

down

info at ensostudio dot ru ¶

3 years ago


Extended SimpleXMLElement:
<?php
class XmlElement extends \SimpleXMLElement
{
    public static function factory(string $root): self
    {
        return new static('<?xml version="1.0" encoding="UTF-8"?><'.$root.'/>', LIBXML_BIGLINES | LIBXML_COMPACT);
    }

    /**
      * @param iterable $attributes An array of element attributes as name/value pairs
      * @return $this
      */
    public function addAttributes(iterable $attributes)
    {
        foreach ($attributes as $name => $value) {
            $this->addAttribute($name, $value);
        }

        return $this;
    }

    /**
      * @param string $name The sub-element name
      * @param string|array|null $valueOrAttributes The sub-element value or an array of attributes
      * @param string|null $namespace The sub-element namespace
      * @return static|null
      */
    public function addChild($name, $valueOrAttributes = null, $namespace = null)
    {
        if (is_array($valueOrAttributes)) {
            $child = parent::addChild($name, null, $namespace);
            foreach ($valueOrAttributes as $name => $value) {
                $child->addAttribute($name, $value);
            }
        } else {
            $child = parent::addChild($name, $valueOrAttributes, $namespace);
        }

        return $child;
    }

    /**
      * @param iterable $childs An array of sub-elements as name/value(or attributes) pairs
      * @return $this
      */
    public function addChilds(iterable $childs)
    {
        foreach ($childs as $name => $value) {
            $this->addChild($name, $value);
        }

        return $this;
    }
}
?>

down

tudor at culise dot net ¶

17 years ago


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.

down

ahmad dot mayahi at gmail dot com ¶

8 years ago


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);

down

bertolini dot cedric at me dot com ¶

10 years ago


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.

down

kumarldh at gmail dot com ¶

13 years ago


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();

}

?>

down

-1

uramihsayibok, gmail, com ¶

15 years ago


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.

down

-2

Phil Cross ¶

10 years ago


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;
    }
?>

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