Document and test FastAPI integration

README.md

@@ -57,6 +57,36 @@ anyio.run(fastenv.dump_dotenv, dotenv)
 # Path('/path/to/this/dir/.env')
 ```
 
+Use fastenv in your FastAPI app:
+
+```py
+from contextlib import asynccontextmanager
+from typing import AsyncIterator
+
+import fastenv
+from fastapi import FastAPI, Request
+
+
+@asynccontextmanager
+async def lifespan(_: FastAPI) -> AsyncIterator[dict[str, fastenv.DotEnv]]:
+ """Configure app lifespan.
+
+ https://fastapi.tiangolo.com/advanced/events/
+ https://www.starlette.io/lifespan/
+ """
+ settings = await fastenv.load_dotenv(".env")
+ yield {"settings": settings}
+
+
+app = FastAPI(lifespan=lifespan)
+
+
+@app.get("/settings")
+async def get_settings(request: Request) -> dict[str, str]:
+ settings = request.state.settings
+ return dict(settings)
+```
+
 ## Documentation
 
 Documentation is built with [Material for MkDocs](https://squidfunk.github.io/mkdocs-material/), deployed on [Vercel](https://vercel.com/), and available at [fastenv.bws.bio](https://fastenv.bws.bio) and [fastenv.vercel.app](https://fastenv.vercel.app).

docs/index.md

@@ -56,3 +56,33 @@ import anyio
 anyio.run(fastenv.dump_dotenv, dotenv)
 # Path('/path/to/this/dir/.env')
 ```
+
+Use fastenv in your FastAPI app:
+
+```py
+from contextlib import asynccontextmanager
+from typing import AsyncIterator
+
+import fastenv
+from fastapi import FastAPI, Request
+
+
+@asynccontextmanager
+async def lifespan(_: FastAPI) -> AsyncIterator[dict[str, fastenv.DotEnv]]:
+ """Configure app lifespan.
+
+ https://fastapi.tiangolo.com/advanced/events/
+ https://www.starlette.io/lifespan/
+ """
+ settings = await fastenv.load_dotenv(".env")
+ yield {"settings": settings}
+
+
+app = FastAPI(lifespan=lifespan)
+
+
+@app.get("/settings")
+async def get_settings(request: Request) -> dict[str, str]:
+ settings = request.state.settings
+ return dict(settings)
+```

pyproject.toml

@@ -48,6 +48,7 @@ httpx = [
 ]
 tests = [
  "coverage[toml]>=7,<8",
+ "fastapi>=0.110.1,<0.111",
  "freezegun>=1,<2",
  "httpx>=0.23,<1",
  "pytest>=8.1.1,<9",

tests/test_fastapi.py

@@ -0,0 +1,53 @@
+import os
+from contextlib import asynccontextmanager
+from typing import AsyncGenerator, AsyncIterator
+
+import pytest
+from anyio import Path
+from fastapi import FastAPI, Request
+from fastapi.testclient import TestClient
+
+import fastenv
+
+
+@asynccontextmanager
+async def lifespan(_: FastAPI) -> AsyncIterator[dict[str, fastenv.DotEnv]]:
+ """Configure app lifespan.
+
+ https://fastapi.tiangolo.com/advanced/events/
+ https://www.starlette.io/lifespan/
+ """
+ env_file = os.environ["ENV_FILE"]
+ settings = await fastenv.load_dotenv(env_file)
+ yield {"settings": settings}
+
+
+app = FastAPI(lifespan=lifespan)
+
+
+@app.get("/settings")
+async def get_settings(request: Request) -> dict[str, str]:
+ settings = request.state.settings
+ return dict(settings)
+
+
+@pytest.fixture
+async def test_client(
+ env_file: Path, monkeypatch: pytest.MonkeyPatch
+) -> AsyncGenerator[TestClient, None]:
+ """Instantiate a FastAPI test client.
+
+ https://fastapi.tiangolo.com/tutorial/testing/
+ https://www.starlette.io/testclient/
+ """
+ monkeypatch.setenv("ENV_FILE", str(env_file))
+ with TestClient(app) as test_client:
+ yield test_client
+
+
+@pytest.mark.anyio
+async def test_fastapi_with_fastenv(test_client: TestClient) -> None:
+ """Test loading a dotenv file into a FastAPI app with fastenv."""
+ response = test_client.get("/settings")
+ response_json = response.json()
+ assert response_json["AWS_ACCESS_KEY_ID_EXAMPLE"] == "AKIAIOSFODNN7EXAMPLE"