Files
openapi-first/openapi_first/binder.py
Vishesh 'ironeagle' Bangotra a2169b2bb1 add spec-driven auth dependency injection
- security.py: parse securitySchemes, resolve {ENV_VAR} from env,
  generate FastAPI Depends for Bearer JWT introspection
- app.py: extract schemes, build deps, pass to binder at init
- binder.py: inject Depends() per operation based on spec's security
- __init__.py: export security module
- pyproject.toml: add httpx dependency
2026-07-17 21:00:23 +05:30

119 lines
3.9 KiB
Python

"""
# Summary
OpenAPI-driven route binding for FastAPI.
This module is responsible for translating an OpenAPI 3.x specification
into concrete FastAPI routes. It enforces a strict one-to-one mapping
between OpenAPI operations and Python handler functions using `operationId`.
Notes:
**Core Responsibility:**
- Read path + method definitions from an OpenAPI specification.
- Resolve each `operationId` to a Python callable.
- Register routes with FastAPI using `APIRoute`.
- Fail fast when contract violations are detected.
**Design Constraints:**
- All routes MUST be declared in the OpenAPI specification.
- All OpenAPI operations MUST define an `operationId`.
- Every `operationId` MUST resolve to a handler function.
- Handlers are plain Python callables (no decorators required).
- No implicit route creation or inference is allowed.
**Constraints:**
- This module intentionally does NOT:
- Perform request or response validation.
- Generate Pydantic models.
- Modify FastAPI dependency injection.
- Interpret OpenAPI semantics beyond routing metadata.
"""
from typing import Any
from fastapi.routing import APIRoute
from .errors import MissingOperationHandler
def bind_routes(
app,
spec: dict,
routes_module,
security_deps: dict[str, list[Any]] | None = None,
) -> None:
"""
Bind OpenAPI operations to FastAPI routes.
Args:
app (fastapi.FastAPI):
The FastAPI application instance to which routes will be added.
spec (dict):
Parsed OpenAPI 3.x specification dictionary.
routes_module (module):
Python module containing handler functions. Each handler's name MUST
exactly match an OpenAPI `operationId`.
security_deps (dict | None):
Optional mapping of ``METHOD:/path`` → ``list[Depends(...)]``
generated from the spec's ``securitySchemes`` and per-operation
``security`` fields.
Raises:
MissingOperationHandler:
If an ``operationId`` is missing from the spec or if no corresponding
handler function exists in the routes module.
Notes:
**Responsibilities:**
- Iterates through the OpenAPI specification paths and methods.
- Resolves each ``operationId`` to a handler function, and registers
a corresponding ``APIRoute`` on the FastAPI application.
- Injects FastAPI ``Depends()`` for each security requirement found
on the operation or inherited from the top-level ``security`` field.
**Guarantees:**
- Route registration is deterministic and spec-driven. No route
decorators are required or supported. Handler resolution errors
surface at application startup.
"""
paths = spec.get("paths", {})
security_deps = security_deps or {}
for path, methods in paths.items():
for http_method, operation in methods.items():
operation_id = operation.get("operationId")
if not operation_id:
raise MissingOperationHandler(
path=path,
method=http_method,
)
try:
endpoint = getattr(routes_module, operation_id)
except AttributeError:
raise MissingOperationHandler(
path=path,
method=http_method,
operation_id=operation_id,
)
key = f"{http_method.upper()}:{path}"
deps = security_deps.get(key, [])
route = APIRoute(
path=path,
endpoint=endpoint,
methods=[http_method.upper()],
dependencies=deps,
name=operation_id,
)
app.router.routes.append(route)