bluem / xmltransformer
PHP library for transforming XML into XML, HTML, plaintext, …
Installs: 2 064
Dependents: 0
Suggesters: 0
Security: 0
Stars: 9
Watchers: 5
Forks: 1
Open Issues: 0
Requires
- php: >=8.2
- ext-xmlreader: *
Requires (Dev)
- friendsofphp/php-cs-fixer: ^3.64
- kubawerlos/php-cs-fixer-custom-fixers: ^3.22
- phpstan/phpstan: ^1.12
- phpunit/phpunit: ^11.0
README
Overview
XMLTransformer is a PHP library for transforming any kind of input XML into an output string. This output string does not have to be XML, but can also be, for instance, HTML or plain text.
It has no dependencies besides PHP itself, no known bugs and 100% test coverage.
Transformations
XMLTransformer is able to …
- Remove tags, including or excluding the tag’s content
- Rename attributes
- Remove attributes
- Add attributes
- Change attributes’ values
- Insert content before and after a tag
- Insert content at the beginning or end of tag content
- Transform a tag including all of its content by passing it to a user-defined closure
- Perform any combination of the above
- Modify the content of text nodes
When to use
In my opinion, XMLTransformer performs very well if the input XML and the output to be produced are similarly structured. Moreover, if data from the input XML has to be processed by an existing PHP codebase, it is possibly cleaner and simpler to use XMLTransformer instead of XSL-T.
When not to use
When the input data has to be re-arranged, you are probably better off with XSL-T, as this is something that XMLTransformer does not provide. (Although to some extent it can be done with appropriate callback code.) Of course you are free to combine XSL-T with XMLTransformer to get the best of both worlds, if one is not enough.
Installation
The recommended way to install this library is through Composer: composer require bluem/xmltransformer
. As the library uses semantic versioning, you can define version constraints in composer.json
so that any non-major updates are allowed.
Alternatively, you can clone the repository using git or download an archived release.
Usage
You pass the input XML and the name of a callback function or a callback method (specified as usual, using [$object, 'methodName']
syntax) or an anonymous function / closure to XMLTransformer
.
For each tag (opening, closing or empty) the callback function will be called with the tag’s name, its attributes and information on whether it is an opening, empty or closing tag. Now, your function / method / closure can return one of three things:
- An array (which describes what transformation(s) should be performed – see below)
false
(meaning: discard this tag, its attributes as well as any tags and any child elements)null
(meaning: don’t modify anything – this is the default behaviour, i.e.: if the callback returns nothing, nothing is changed.
Callback function arguments
The callback function / method / closure is called with three arguments:
- The element / tag name
- The element / tag’s attributes (an associative array of name=>value pairs, where the name contains the namespace, if the attribute is not from the default namespace)
- An element type constant, which will be
XMLTransformer::ELEMENT_OPEN
for an opening tag,XMLTransformer::ELEMENT_EMPTY
for an empty tag andXMLTransformer::ELEMENT_CLOSE
for a closing tag.
Please note that the attributes will always be given, even for a closing tag.
The transformation description array
When you wish to perform a transformation, you must return an associative array. In this case, the following keys can be used:
XMLTransformer::RULE_TAG
: Returning false for key “tag” removes the tag (incl. its attributes, of course), but keeps any enclosed content. Returning a string will set the tag name to that string.XMLTransformer::RULE_ADD_BEFORE
: Will insert the given string before the opening tagXMLTransformer::RULE_ADD_AFTER
: Will insert the given string after the closing tagXMLTransformer::RULE_ADD_START
: Will insert the given string right after the opening tagXMLTransformer::RULE_ADD_END
: Will insert the given string right before the closing tagXMLTransformer::RULE_TRANSFORM_OUTER
: Value must be a closure, which will be passed the element itself incl. all its content as a string. The closure’s return value will replace the element.XMLTransformer::RULE_TRANSFORM_INNER
: Value must be a closure, which will be passed the element’s content as a string. The closure’s return value will replace the element.
Additionally, for handling attributes, array keys in the form of “@” can be used, where is the attribute name (with namespaces, if not from the default namespace). The value of such an array key can be one of:
- false: The attribute will be removed
- A string starting with “@”: The attribute will be renamed
- A string: The attribute value will be set to this string.
For instance, this return array …
return [ XMLTransformer::RULE_TAG => 'demo', '@xml:id' => 'id', '@foo' => false, XMLTransformer::RULE_ADD_AFTER => '!', ];
… means:
- Rename the tag to “demo”
- Rename the
xml:id
attribute toid
- Remove the
@foo
attribute - Insert the string “!” after the closing tag (or directly after the tag, if it’s an empty tag)
Please note that (as XMLTransformer
is not restricted to produce XML) no automatic escaping is done to values returned by the array. Only exception: attribute values, as XMLTransformer assumes that if you set attribute values, you want XML or HTML output.
Passing attributes by reference
The callback can accept the arguments’ array by reference, therefore allowing direct manipulation of the attributes. This can be handy when changing or removing a large number of attributes or when only a prefix or suffix (or namespace) of attributes’ names is known in advance.
See below for an example.
Examples
All of the examples below assume that your code includes the usual boilerplate code for Composer autoloading:
require 'vendor/autoload.php';
Hello world
use BlueM\XMLTransformer; echo XMLTransformer::transformString( '<root><element>Hello world</element></root>', function($tag, $attributes, $opening) { return [ XMLTransformer::RULE_TAG => false, // <-- Removes tag, but keeps content ]; } ); // Result: “Hello World”.
Multilingual Hello world
use BlueM\XMLTransformer; function transform($tag, $attributes, $opening) { if ('hello-world' == $tag) { if (isset($attributes['xml:lang']) and 'de' == $attributes['xml:lang']) { $str = 'Hallo Welt'; } else { $str = 'Hello world'; } return [ XMLTransformer::RULE_TAG => false, // <-- Remove the tag, keep content XMLTransformer::RULE_ADD_BEFORE => $str, // <- Insert literal content ]; } if ('root' == $tag) { // We do not want the enclosing <root> tags in the output return [XMLTransformer::RULE_TAG => false]; } } echo XMLTransformer::transformString( '<root><hello-world xml:lang="de" /></root>', 'transform' ); // Result: “Hallo Welt” echo XMLTransformer::transformString( '<root><hello-world xml:lang="en" /></root>', 'transform' ); // Result: “Hello world”
Removing tags including all of their content
echo XMLTransformer::transformString( '<root><remove>Hello </remove>World</root>', function($tag, $attributes, $opening) { switch ($tag) { case 'remove': return false; // <-- Removes tag incl. content case 'root': case 'keep': return [XMLTransformer::RULE_TAG => false]; // <-- Remove tag, keep content break; default: // Returning null is not necessary, as this // is the default behaviour. It is equivalent // to "Do not change anything." return null; } } ); // Result: “World”
Changing attribute values
echo XMLTransformer::transformString( '<root abc="def"></root>', function($tag, $attributes, $opening) { return [ '@abc' => 'xyz' ]; } ); // Result: “<root abc="xyz"></root>” // Please note that empty tags will always be returned with // a space before the slash.
Adding, renaming and removing attributes
echo XMLTransformer::transformString( '<root xml:id="abc"><bla xml:id="def" blah="yes"/></root>', function($tag, $attributes, $opening) { return [ '@foo' => 'bar', // Add attribute "foo" with value "bar" '@blah' => false, // Remove attribute "blah" '@xml:id' => '@id', // Rename attribute "xml:id" to "id" ]; } ); // Result: “<root id="abc" foo="bar"><bla id="def" foo="bar" /></root>” // Please note that empty tags will always be returned with // a space before the slash.
Modifying attributes by reference
echo XMLTransformer::transformString( '<root xml:a="a" xml:b="b" id="foo">Content</root>', function($tag, &$attributes, $opening) { foreach ($attributes as $name => $value) { if ('xml:' === substr($name, 0, 4)) { unset($attributes[$name]); // Drop attributes in "xml" namespace } } } ); // Result: “<root id="foo">Content</root>”
Author & License
This code was written by Carsten Blüm (www.bluem.net) and licensed under the BSD2 license.
Version history
3.0 (2024-10-27)
- Breaking change: requires PHP 8.2
- Breaking change (at least theoretically): trying to apply an outer transformation to an empty tag throws an exception. It did not work in previous versions, anyway, but failed silently.
- General codebase modernization: use modern language features, add PHPStan and php-cs-fixer, fix code style, add typehints, drop redundant doc comments, drop redundant tests
2.0.1 (2020-12-02)
- Fixes an inconsistent behavior in case
null
is returned as value forXMLTransformer::RULE_TAG
(which is not supposed to be done). - Just for the record: tests run successfully on PHP8 (not yet in
.travis.yml
, as Travis CI does not support PHP 8 yet).
2.0 (2018-02-12)
- BC break: minimum PHP version is 7.0
- BC break: introduced class constants for transformation rules which should be used instead of the magic strings used with version 1. This means, that in your code, you should …
- Change string
insend
toXMLTransformer::RULE_ADD_END
- Change string
insafter
toXMLTransformer::RULE_ADD_AFTER
- Change string
insbefore
toXMLTransformer::RULE_ADD_BEFORE
- Change string
insstart
toXMLTransformer::RULE_ADD_START
- Change string
transformInner
toXMLTransformer::RULE_TRANSFORM_INNER
- Change string
transformOuter
toXMLTransformer::RULE_TRANSFORM_OUTER
- Change string
tag
toXMLTransformer::RULE_TAG
- Change string
- BC break: constant
XMLTransformer::ELOPEN
was renamed toXMLTransformer::ELEMENT_OPEN
,XMLTransformer::ELEMPTY
was renamed toXMLTransformer::ELEMENT_EMPTY
andXMLTransformer::ELCLOSE
was renamed toXMLTransformer::ELEMENT_CLOSE
. - Code simplification, modernization
1.2 (2015-12-05)
- Adds missing support for handling CDATA. By default, CDATA sections are retained, but by setting the third argument to
transformString()
to false, CDATA content is replaced with but as PCDATA content with<
and>
and&
escaped.
1.1 (2015-08-15)
- The callback function/method/closure can receive the attributes by reference. See “Passing attributes by reference” above.
- Fix for PHP 5.3 compatibility
1.0 (2012-12-12)
- First public version