Where we left off

This is a short recipe, not a new concept: naive_rag Lesson 24 already taught what lifespan, app.state, and TestClient do and why a FastAPI wrapper is structured this way. Nothing about that changes here, ingest() and ask() (Lesson 22) slot into the exact same shell unmodified. This lesson exists so the course has a complete, runnable service, not to re-teach FastAPI, Lessons 7-8 (cross-modal retrieval and re-attaching the original image) carry this course's real depth.

The code, piece by piece

@asynccontextmanager
async def lifespan(app: FastAPI):
    chroma_client = chromadb.Client()
    app.state.collection = ingest(NOTES_DIR, IMAGES_DIR, chroma_client)
    yield




@app.get("/ask", response_model=AskResponse)
def ask_endpoint(q: str, k: int = 2) -> AskResponse:
    return AskResponse(answer=ask(q, app.state.collection, k))

naive_rag Lesson 24's exact shape, ingest() now takes two directory arguments (notes_dir, images_dir) instead of one, everything else, lifespan running once at startup, one GET /ask route, TestClient running the app in-process, is unchanged.

Checkpoint

  • If lifespan, app.state, or TestClient feel unfamiliar, go back to naive_rag Lesson 24, this lesson deliberately doesn't re-explain them.
  • The only thing specific to this course is that ingest() now builds a mixed-modality collection; the service shell around it is identical to every other course in this series that has one.

If anything here still feels unclear, ask before moving to Lesson 24.