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

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User Contributed Notes 7 notes

up
5
rowan dot collins at gmail dot com
6 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
up
7
tudor at culise dot net
16 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.
up
6
ahmad dot mayahi at gmail dot com
7 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);
up
3
bertolini dot cedric at me dot com
9 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.
up
4
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();
}
?>
up
-2
Phil Cross
9 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;
    }
?>
up
-2
uramihsayibok, gmail, com
14 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.
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