assert data == "Session cookie or query token value is: some-token"
            data = websocket.receive_text()
            assert data == f"Message text was: {message}, for item ID: bar"
            message = "Message two"
            websocket.send_text(message)
            data = websocket.receive_text()
            assert data == "Session cookie or query token value is: some-token"

    client = TestClient(app)
    with client.websocket_connect("/") as websocket:
        data = json.loads(websocket.receive_text())
        assert data == ["app", "index"]


def test_routerindex():
    client = TestClient(app)
    with client.websocket_connect("/router") as websocket:
        data = json.loads(websocket.receive_text())
        assert data == ["app", "router2", "router", "routerindex"]


def test_routerprefixindex():

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

!!! info

    return current_user


@app.post("/token")
async def login_for_access_token(
    form_data: OAuth2PasswordRequestForm = Depends(),
) -> Token:
    user = authenticate_user(fake_users_db, form_data.username, form_data.password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,

    return current_user


@app.post("/token")
async def login_for_access_token(
    form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
) -> Token:
    user = authenticate_user(fake_users_db, form_data.username, form_data.password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,

        client.get("/items/invalidnone")


def test_valid_none_data():
    response = client.get("/items/validnone")
    data = response.json()
    assert response.status_code == 200
    assert data == {"name": "invalid", "price": 3.2, "owner_ids": None}


def test_valid_none_none():
    response = client.get("/items/validnone", params={"send_none": "true"})
    data = response.json()
    assert response.status_code == 200

    * If you didn't use FastAPI and used Starlette directly (or another tool, like Sanic, Flask, Responder, etc) you would have to implement all the data validation and serialization yourself. So, your final application would...

                    "required": ["data"],
                    "type": "object",
                    "properties": {"data": {"$ref": "#/components/schemas/Product"}},
                },
                "Body_create_shop_shops_post": {
                    "title": "Body_create_shop_shops_post",
                    "required": ["data"],
                    "type": "object",

## Recap

With **FastAPI**, by using short, intuitive and standard Python type declarations, you get:

* Editor support: error checks, autocompletion, etc.
* Data "<abbr title="converting the string that comes from an HTTP request into Python data">parsing</abbr>"
* Data validation
* API annotation and automatic documentation

And you only have to declare them once.

    await manager.connect(websocket)
    try:
        while True:
            data = await websocket.receive_text()
            await manager.send_personal_message(f"You wrote: {data}", websocket)
            await manager.broadcast(f"Client #{client_id} says: {data}")
    except WebSocketDisconnect:
        manager.disconnect(websocket)