Building REST Endpoints

Wiring a Pydantic model and Motor together inside a path operation gives you a real REST endpoint.

from fastapi import FastAPI, HTTPException

app = FastAPI()

@app.post("/tasks", response_model=TaskOut)
async def create_task(task: Task):
    result = await tasks_collection.insert_one(task.model_dump())
    created = await tasks_collection.find_one({"_id": result.inserted_id})
    return {**created, "id": str(created["_id"])}

@app.get("/tasks/{task_id}", response_model=TaskOut)
async def get_task(task_id: str):
    task = await tasks_collection.find_one({"_id": ObjectId(task_id)})
    if task is None:
        raise HTTPException(status_code=404, detail="Task not found")
    return {**task, "id": str(task["_id"])}

Key ideas

• {task_id} in the route path becomes a function parameter automatically, FastAPI calls this path parameter binding.
• task: Task as a parameter tells FastAPI to parse and validate the request body as a Task.
• response_model=TaskOut shapes and validates what gets sent back, and shows up correctly in the auto-generated docs.
• Raising HTTPException is how you return a non-200 status code with a message.