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description Generate PHP model classes from FHIR Structure Definitions and ValueSets.
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Overview

The Code Generation component loads FHIR packages from the registry and generates strongly-typed PHP classes from their definitions. A StructureDefinition is FHIR's machine-readable description of a resource or data type, and a ValueSet is a named set of permitted codes. The generator turns them into Resources, DataTypes, Primitives, and Enums. It is the engine behind the fhir:generate and fhir:generate-ig console commands.

Namespace: Ardenexal\FHIRTools\Component\CodeGeneration\.

There are two distinct workflows:

WorkflowPage
Generate the base FHIR models (R4 / R4B / R5)Base FHIR Models
Generate typed extension & profile classes for an Implementation GuideImplementation Guides

How it works

Both commands share the same pipeline, implemented with Nette PhpGenerator:

  1. Package loading — PackageLoader downloads and caches FHIR packages (.tgz) from the FHIR registry (packages.fhir.org), verifying integrity and resolving versions. Cached packages can be reused with --offline.
  2. Definition parsing — loadPackageStructureDefinitions() reads StructureDefinition and ValueSet JSON resources out of each package into a per-version BuilderContext.
  3. Class generation — each StructureDefinition is routed by its kind to a generator that emits a PHP class or enum:
    • kind: resource → Resources (PatientResource, ObservationResource, …)
    • kind: complex-type → DataTypes (HumanName, Address, …)
    • kind: primitive-type → Primitives (StringPrimitive, BooleanPrimitive, …)
    • referenced ValueSet bindings → Enums (AdministrativeGender, …) plus a …Type code wrapper class in DataType/

fhir:generate runs in three global phases — load all requested packages, clear only the output directories for the affected FHIR versions, then generate — so generating one version never clobbers another. It skips logical models and derivation: constraint definitions (profiles and named extensions); those are the domain of fhir:generate-ig.

Core classes

Class Location under …\CodeGeneration\ Responsibility
PackageLoader Package\PackageLoader Download, cache, extract, and parse FHIR packages
BuilderContext Context\BuilderContext Hold definitions, generated types, enums, and namespace registrations during a run
FHIRModelGenerator Generator\FHIRModelGenerator Generate a PHP class from a base StructureDefinition
FHIRValueSetGenerator Generator\FHIRValueSetGenerator Generate a PHP enum from a ValueSet
FHIRExtensionGenerator Generator\FHIRExtensionGenerator Generate typed extension classes (type: Extension)
FHIRProfileGenerator Generator\FHIRProfileGenerator Generate profile subclasses (derivation: constraint)
ErrorCollector Generator\ErrorCollector Collect non-fatal errors/warnings for end-of-run reporting

See Base FHIR Models for the generator APIs in detail and Implementation Guides for the extension/profile generators.

{% hint style="warning" %} Generated model files under src/Component/Models/src/ are never hand-edited — always regenerate. See Generated Output Structure. {% endhint %}