py: profiles

[MikhailArtemyev]

PY: Python profile class generation

Implements generateProfile: true for the Python generator — produces a typed wrapper class for each FHIR profile alongside the base Pydantic models.

Runtime library

A static profile_helpers.py is copied into each profiles/ package. It provides all slice/extension/validation utilities the generated classes depend on: build_resource, ensure_profile, apply_slice_match, get_array_slice, set_array_slice, push_extension, get_extension_value, extract_complex_extension, ensure_slice_defaults, and validation helpers.

Profile class API

Each generated profile class exposes:

• create(*, required_field: T, ...) -> Profile — constructs a valid resource with all fixed values, required slices, and meta.profile pre-populated
• apply(resource) -> Profile — wraps an existing resource (adds canonical URL to meta.profile)
• from_resource(resource) -> Profile — wraps and validates; raises on errors
• to_resource() -> BaseType — unwraps back to the Pydantic model
• validate() -> dict[str, list[str]] — checks required fields, fixed value constraints, slice cardinality, must-support fields (warnings), prohibited choices, enum values, and reference target types

Field accessors

• Required and value-constrained fields get typed get_X / set_X methods; setters return self for fluent chaining
• Choice types (value[x]) promoted to direct params when only one variant is constrained

Extension accessors

Each ProfileExtension generates overloaded get_X / set_X methods with three return modes:

• default — flat Python value (e.g. dict, str, Coding)
• "raw" — bare Extension model
• "profile" — wrapped in the extension's own profile class (when one exists in the same package)

Supports complex (sub-extension), single-value, and generic extension shapes.

Slice accessors

Each named slice generates get_X / set_X methods that read and write into the correct position within the array field. Supports:

• Value-discriminated slices (match on fixed field values)
• Type-discriminated slices (resource-type discriminator), including unbounded (max: *) variants with get_X() -> list[T] / set_X(values: list[T])
• Constrained choice slices (e.g. BP component.value[x] fixed to valueQuantity) — automatically wraps/unwraps the choice key

Example

Added examples/python-profiles/us-core-demo/ — Python equivalent of the TypeScript US Core demo:

Before (raw Pydantic):

obs = Observation(
    resource_type="Observation",
    status="final",
    code=CodeableConcept(coding=[Coding(code="85354-9", system="http://loinc.org")]),
    component=[ObservationComponent(...)],
    ...
)

After (profile class):

bp = UscoreBloodPressureProfile.create(status="final", subject=Reference(reference="Patient/123"))
bp.set_effective_date_time("2026-04-15")
bp.set_systolic({"value": 120, "unit": "mmHg", "system": "http://unitsofmeasure.org", "code": "mm[Hg]"})
bp.set_diastolic({"value": 80, "unit": "mmHg", "system": "http://unitsofmeasure.org", "code": "mm[Hg]"})
errors = bp.validate()["errors"]  # []

load.py converts patients.csv (5 patients) to a FHIR transaction bundle; avg.py reads it back via profile accessors and prints average BP.

[ryukzak]

Please, rebase on the main.