SimpleXMLElement::addAttribute

(PHP 5 >= 5.1.3, PHP 7, PHP 8)

SimpleXMLElement::addAttribute Añade un atributo al elemento SimpleXML

Descripción

public SimpleXMLElement::addAttribute(string $name, string $value = ?, string $namespace = ?): void

Añade un atributo al elemento SimpleXML.

Parámetros

name

El nombre del atributo a añadir.

value

El valor del atributo.

namespace

Si se especifica, indica el espacio de nombres al que pertenece el atributo.

Valores devueltos

No devuelve ningún valor.

Ejemplos

Nota:

Los ejemplos enumerados podrían incluir example.php, que hace referencia al string XML encontrado en el primer ejemplo de la guía de uso básico.

Ejemplo #1 Añadir atributos e hijos a un elemento SimpleXML

<?php

include 'example.php';

$sxe = new SimpleXMLElement($xmlstr);
$sxe->addAttribute('tipo', 'documental');

$pelicula = $sxe->addChild('pelicula');
$pelicula->addChild('titulo', 'PHP2: Más historias del Parser');
$pelicula->addChild('argumento', 'Todo sobre la gente que lo hace funcionar.');

$personajes = $pelicula->addChild('personajes');
$personaje = $personajes->addChild('personaje');
$personaje->addChild('nombre', 'Sr. Parser');
$personaje->addChild('actor', 'John Doe');

$puntuacion = $pelicula->addChild('puntuacion', '5');
$puntuacion->addAttribute('tipo', 'estrellas');

echo
$sxe->asXML();

?>

El resultado del ejemplo sería algo similar a:

<?xml version="1.0" standalone="yes"?>
<peliculas tipo="documental">
 <pelicula>
  <titulo>PHP: Tras el Parser</titulo>
  <personajes>
   <personaje>
    <nombre>Srta. Programadora</nombre>
    <actor>Onlivia Actora</actor>
   </personaje>
   <personaje>
    <nombre>Sr. Programador</nombre>
    <actor>El Actor</actor>
   </personaje>
  </personajes>
  <argumento>
   Así que, este lenguaje. Es como, un lenguaje de programación. ¿O es un
   lenguaje interpretado? Lo descubrirás en esta intrigante y temible parodia
   de un documental.
  </argumento>
  <grandes-lineas>
   <linea>PHP soluciona todos los problemas web</linea>
  </grandes-lineas>
  <puntuacion tipo="pulgares">7</puntuacion>
  <puntuacion tipo="estrellas">5</puntuacion>
 </pelicula>
 <pelicula>
  <titulo>PHP2: Más historias del Parser</titulo>
  <argumento>Todo sobre la gente que lo hace funcionar.</argumento>
  <personajes>
   <personaje>
    <nombre>Sr. Parser</nombre>
    <actor>John Doe</actor>
   </personaje>
  </personajes>
  <puntuacion tipo="estrellas">5</puntuacion>
 </pelicula>
</peliculas>

Ver también

add a note

User Contributed Notes 7 notes

up
4
Patanjali
6 years ago
You cannot use this to update an existing attribute's value.

Instead, get a DOM version of the SimpleXMLElement and use setAttribute, as per:

$XML = '<element a="aa">Text</element>';
$snode = new simple_xml_element($XML);

$dnode = dom_import_simplexml($snode);
$dnode->setAttribute('a', 'bb');

Resulting XML for the node is:
<element a="bb">Text</element>
up
3
booleer at yahoo dot it
12 years ago
If the attribute already exists, addAttribute does nothing.

example:
<?php
$xml_string
= <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<root>
   <item id="foo">
<root>
XML;

$xml = simplexml_load_string($xml_string);
$xml->item->addAttribute('id', 'bar');
echo
$xml->asXML();
?>

The above examples will output:
<?xml version="1.0" encoding="UTF-8"?>
<root>
   <item id="foo">
<root>
up
1
p.servus
11 years ago
If you need an Namespace, you must write a Prefix of the Namespace + the Name of the Attribute ("prefix:name") as the first parameter AND the uri as the third one. (I don't know why?!)

Example code:
<?php
$xml
= new SimpleXMLElement("<packagedElement></packagedElement>");
$xml->addAttribute("xmi:type", "uml:Class", "http://schema.omg.org/spec/XMI/2.1");
echo
$xml->asXml();
?>

Output:
<packagedElement xmlns:xmi="http://schema.omg.org/spec/XMI/2.1" xmi:type="uml:Class"></packagedElement>
up
0
caffeinatedbits
1 month ago
Just found another gem. Need to remove an attribute? That's simple too!

<?php

$xml
= <<<EOF
<?xml version="1.0" encoding="utf-8" ?>
<Animals>
    <Dog breed="chihuahua"/>
</Animals>
EOF;

$animals = new SimpleXMLElement($xml);

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua"/>

unset($animals->Dog['breed']);

echo
$animals->Dog->asXML();
// <Dog/>

?>
up
0
caffeinatedbits
1 month ago
I needed a way to update an attribute, but I could not find any documented way to do this.

After much experimentation, here's my findings of what works - the answer was so simple it took me 8 tries to figure it out :-)

Given the following example:

<?php

$xml
= <<<EOF
<?xml version="1.0" encoding="utf-8" ?>
<Animals>
    <Dog/>
</Animals>
EOF;

$animals = new SimpleXMLElement($xml);

echo
$animals->Dog->asXML();
// <Dog/>

?>

Test #6 - maybe directly modifying the attributes() Iterator like an array will secretly call __set() magic method?

TL;DR: yep

<?php

...

$animals->Dog->addAttribute('breed', "chihuahua");

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

$dogAttrs = $animals->Dog->attributes();
// object(SimpleXMLElement)#4 (1) {
// ["@attributes"]=>
//   array(1) {
//     ["breed"]=>
//     string(9) "chihuahua"
//   }
// }

$dogAttrs['breed'] = "poodle";
// works!

echo $animals->Dog->asXML();
// <Dog breed="poodle">

?>

Test #7 - maybe I don't even need to call attributes() at all?

TL;DR: I sure don't!

<?php

...

$animals->Dog->addAttribute('breed', "chihuahua");

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

$animals->Dog['breed'] = "poodle";
// works!

echo $animals->Dog->asXML();
// <Dog breed="poodle">

?>

Test #8 - Maybe I never needed to call addAttribute() in the first place?

TL;DR: nope, I can skip that altogether!

<?php

...

$animals->Dog['breed'] = "chihuahua";
// works!

echo $animals->Dog->asXML();
// <Dog breed="chihuahua">

$animals->Dog['breed'] = "poodle";
// works!

echo $animals->Dog->asXML();
// <Dog breed="poodle">

?>

FYI: I also submitted another separate note with what does NOT work just in case you, like me, are curious and tempted to try another way.
up
0
caffeinatedbits
1 month ago
I needed a way to update an attribute, but I could not find any documented way to do this.

TL;DR: It's not only possible, but unbelievably simple. See the other note I submitted for what actually works (sorry, I could not fit it all in a single note due to the 4095 character limit).

After much experimentation, here's my findings of what does NOT work; hopefully, it saves you the time and frustration it cost me.

Given the following example:

<?php

$xml
= <<<EOF
<?xml version="1.0" encoding="utf-8" ?>
<Animals>
    <Dog/>
</Animals>
EOF;

$animals = new SimpleXMLElement($xml);

echo
$animals->Dog->asXML();
// <Dog/>

?>

Test #1 - attempt to call addAttribute() twice

TL;DR: PHP Warning: SimpleXMLElement::addAttribute(): Attribute already exists

<?php

...

$animals->Dog->addAttribute('breed', "chihuahua");

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua"/>

$animals->Dog->addAttribute('breed', "poodle");
// PHP Warning: SimpleXMLElement::addAttribute(): Attribute already exists

echo $animals->Dog->asXML();
// <Dog breed="chihuahua"/>

?>

Test #2 - attempt to iterate attributes() (an Iterator) by reference

TL;DR: An iterator cannot be used with foreach by reference

<?php

...

$animals->Dog->addAttribute('breed', "chihuahua");

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

try {
    foreach (
$animals->Dog->attributes() as $attr => &$value) {
        if (
"breed" === $attr) {
           
$value = "poodle";
        }
    }
} catch (
Throwable $e) {
    echo
$e->getMessage();
   
// An iterator cannot be used with foreach by reference
}

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

?>

Test #3 - attempt to re-parse child element and then call addAttribute() on the newly parsed element, as suggested in a note I found here

TL;DR: PHP Warning: SimpleXMLElement::addAttribute(): Attribute already exists

<?php

...

$animals->Dog->addAttribute('breed', "chihuahua");

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

$animals->Dog = new SimpleXMLElement($animals->asXML());

$animals->Dog->addAttribute('breed', "poodle");
// PHP Warning: SimpleXMLElement::addAttribute(): Attribute already exists

echo $animals->Dog->asXML();
// <Dog breed="chihuahua">

?>

Test #4 - attempt to modify @attributes array element

TL;DR: PHP Notice:  Indirect modification of overloaded element of SimpleXMLElement has no effect

<?php

...

$animals->Dog->addAttribute('breed', "chihuahua");

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

$dogAttrs = $animals->Dog->attributes();
// object(SimpleXMLElement)#4 (1) {
// ["@attributes"]=>
//   array(1) {
//     ["breed"]=>
//     string(9) "chihuahua"
//   }
// }

$dogAttrs['@attributes']['breed'] = "poodle";
// PHP Notice:  Indirect modification of overloaded element of SimpleXMLElement has no effect

echo $animals->Dog->asXML();
// <Dog breed="chihuahua">

?>

Test #5 - cast attributes() to array and set value of 'breed' element

TL;DR: does not update value in original object

<?php

...

$animals->Dog->addAttribute('breed', "chihuahua");

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

$dogAttrs = (array) $animals->Dog->attributes();
// array(1) {
//     ["@attributes"]=>
//   array(1) {
//         ["breed"]=>
//     string(9) "chihuahua"
//   }
// }

$dogAttrs['@attributes']['breed'] = "poodle";

echo
$animals->Dog->asXML();
// <Dog breed="chihuahua">

?>
up
0
sarlak
11 years ago
You can access a node child with his name this way :

<?php
$root
= new SimpleXMLElement($filePath);
echo
$root->nodeName->attributes;

// It works recursivly so this will work too
echo $root->nodeName->subNodeName->attributes();
?>

But if you want to ADD an attribute to a children you MUST use the children() method to access and modfiy it or it will modify the parent's attributes.

<?php
// Add a subnode
$element->nodeName->addChild('subNodeName', "whatever you want");
               
// Get the pos in the childrens of the parent node
$lastNodePos = $element->nodeName->count()-1;

// Get the parents node childrens
$nodeChildrens = $element->nodeName->children();

// Add an attribute to the last created
$nodeChildrens[$lastNodePos]->addAttribute('attributeName', "The attribute value);
?>
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