Fhir Code Generation Laravel Package

Getting Started

Minimal Setup

1. Installation Add the package via Composer:

   composer require ardenexal/fhir-code-generation
   

   Ensure php-fhir-tools (parent package) is also installed if dependencies are shared.

2. First Use Case Generate a FHIR resource class (e.g., Patient) from a FHIR profile or schema:

   use Ardenexal\FhirCodeGeneration\Generator;
   
   $generator = new Generator();
   $resourceClass = $generator->generateFromProfile('Patient', 'path/to/profile.json');
   

   Save the output to a file:

   file_put_contents('app/FHIR/Patient.php', $resourceClass);
   

3. Key Files

   • Review src/Generator.php for core logic.
   • Check examples/ (if available) for sample profiles/schemas.

Implementation Patterns

Workflow: Profile-to-Class Generation

1. Profile Input Use FHIR profiles (JSON/XML) to define custom resources:

   $profile = json_decode(file_get_contents('profiles/CustomObservation.json'), true);
   $generator->generateFromProfile('CustomObservation', $profile);
   

2. Schema-Based Generation For base FHIR schemas (e.g., Patient, Encounter):

   $generator->generateFromSchema('Encounter', 'FHIR/R4');
   

3. Integration with Laravel

   • Store generated classes in app/FHIR/ and autoload via composer.json:

     "autoload": {
       "psr-4": {
         "App\\FHIR\\": "app/FHIR/"
       }
     }
     

   • Use Laravel’s service container to bind the generator:

     $this->app->singleton(Generator::class, function ($app) {
         return new Generator(config('fhir.generator'));
     });
     

4. Batch Processing Generate multiple resources in a loop:

   $profiles = ['Patient', 'Observation', 'Medication'];
   foreach ($profiles as $resource) {
       $generator->generateFromProfile($resource, "profiles/{$resource}.json");
   }
   

Gotchas and Tips

Pitfalls

1. Dependency Conflicts

   • Ensure php-fhir-tools (parent package) is installed and compatible. Check for version mismatches in composer.json.

2. Profile Validation

   • Invalid profiles may crash the generator. Validate with a FHIR validator (e.g., HAPI FHIR before generation.

3. Namespace Collisions

   • Generated classes may conflict with existing Laravel namespaces. Prefix with FHIR\\ or use a dedicated namespace in composer.json:

     "autoload-dev": {
       "psr-4": {
         "FHIR\\": "app/FHIR/"
       }
     }
     

4. Caching Generated Classes

   • Regenerate classes only when profiles change. Cache outputs in storage/fhir-generated/ and skip regeneration if files exist.

Debugging

• Verbose Output: Enable debug mode in the generator (if supported) or log raw profile data:

  \Log::debug('Profile data:', ['profile' => $profile]);
  

• Check Generated Code: Validate against FHIR specs manually or use a linter like phpstan.

Extension Points

1. Custom Templates Override default class templates by extending the generator:

   class CustomGenerator extends Generator {
       protected function getClassTemplate(): string {
           return file_get_contents('custom/FHIRClassTemplate.twig');
       }
   }
   

2. Post-Processing Hook into the generation pipeline to modify classes (e.g., add Laravel traits):

   $generator->setPostProcessor(function (string $classCode) {
       return str_replace('class Patient', 'class Patient extends \Illuminate\Database\Eloquent\Model', $classCode);
   });
   

3. FHIR Version Support Explicitly specify FHIR versions (e.g., R4, STU3) to avoid ambiguity:

   $generator->generateFromSchema('Patient', 'FHIR/R4');