php-fhir

Tools for creating PHP classes from the HL7 FHIR Specification

If you're looking to use the classes generated by this library, you may want the php-fhir-generated repo instead.

• php-fhir
• Install as Standalone Generator
• Install as Library
• Version Table
• Basic Usage
  • Class Generation
    • Generation Example
  • Data Querying
  • Response Parsing
  • Parsing Example
• Serialization
  • JSON Serialization
  • XML Serialization
• Testing
  • TODO
  • Suggestions and help

Install as Standalone Generator

If you wish to use this package as a standalone generator:

1. Check out the desired branch or tag
2. Execute composer install from root of project directory
3. Execute ./bin/generate.sh
4. Answer all prompts
   • If no custom configuration file is defined, definitions will be downloaded to ./input and classes will be generated under ./output
   • You can execute ./bin/generate.sh --help for details on how to utilize this script
   • You can configure various aspects of this script by altering the values in ./bin/config.php

This script will download configured major versions of FHIR into the input folder and generate classes for every version in the output folder.

Install as Library

If you wish to use the generator as part of a project, you can include it as a composer dependency:

composer require dcarbone/php-fhir

From there, you can reference the Example block for a quick example on how to configure and execute the generator.

Version Table

PHPFHIR Version	PHP Versions	FHIR Versions
v2	5.4-7.4	DSTU1, DSTU2, STU3, R4 (<v4.3.0)
v3	8.1+	DSTU1, DSTU2, STU3, R4, R5

Basic Usage

The first step is to determine the version of the FHIR spec your implementation supports. Once done, download the appropriate class definition XSDs from http://hl7.org/fhir/directory.html.

Uncompress the XSD's and place them in a directory that is readable by PHP's runtime user.

Next comes the fun:

Class Generation

The class generator utility included with this library is designed to parse the XSD's provided by the FHIR group into PHP classes, complete with markup and type hinting.

There are 2 important things to note with this section:

1. Your exact implementation will probably vary, don't hesitate to ask if you need some help
2. The class generation should be run ONCE per FHIR version. Once the classes have been generated they should only ever be re-generated if your server switches to a new FHIR spec

Generation Example

You can view an example config array here: bin/config.php.

// first, build new configuration class
$config = new \DCarbone\PHPFHIR\Config(require 'config.php');

// next, iterate through all configured versions and render code:
foreach ($config->getVersions() as $versionConfig) {
    $versionConfig->getDefinition()->getBuilder()->render();
}

Data Querying

Currently only a very simple client intended for debugging use is generated. A future goal is to generate a more fully-featured client.

Response Parsing

As part of the class generation above, a response parsing class called PHPFHIRResponseParser will be created and added into the root namespace directory. It currently supports JSON and XML response types.

The parser class takes a single optional boolean argument that will determine if it should attempt to load up the generated Autoloader class. By default it will do so, but you are free to configure your own autoloader and not use the generated one if you wish.

Parsing Example

require 'path to PHPFHIRResponseParserConfig.php';
require 'path to PHPFHIRResponseParser.php';

// build config
$config = new \YourConfiguredNamespace\PHPFHIRConfig([
    'registerAutoloader' => true, // use if you are not using Composer
    'libxmlOpts' => LIBXML_NONET | LIBXML_BIGLINES | LIBXML_PARSEHUGE | LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD | LIBXML_NOXMLDECL // choose different libxml arguments if you want, ymmv.
    'rootXmlns' => 'https://hl7.org/fhir', // a specific root xmlns to use, if the source does not return one
    'overrideSourceXmlns' => true, // set this to true if you want the 'rootXmlns' value you defined to override any value seen from source 
]);

// build parser
$parser = new \YourConfiguredNamespace\PHPFHIRResponseParser($config);

// provide input, receive output.
$object = $parser->parse($yourResponseData);

Serialization

JSON Serialization

$json = json_encode($object);

XML Serialization

// To get an instance of \XMLWriter...
$xw = $object->xmlSerialize(null, $yourConfigInstance);

// to get as XML string...
$xml = $xw->outputMemory(true);

// you can alternatively have the output written directly to a file:
$xw = new \YourConfiguredNamespace\PHPFHIRXmlWriter();
$xw->openUri('file:///some/directory/fhir-resource.xml');
$object->xmlSerialize($xw, $yourConfigInstance);

XML Serialization utilizes XMLWriter.

Testing

As part of class generation, a directory & namespace called PHPFHIRTests is created under the root namespace and output directory.

TODO

• Implement event or pull-based XML parsing for large responses

Suggestions and help

If you have some suggestions for how this lib could be made more useful, more applicable, easier to use, etc, please let me know.