```Python hl_lines="3"
{!../../../docs_src/behind_a_proxy/tutorial002.py!}
```

Passing the `root_path` to `FastAPI` would be the equivalent of passing the `--root-path` command line option to Uvicorn or Hypercorn.

### About `root_path`

        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/": {
                "get": {
                    "summary": "Read Root",
                    "operationId": "read_root__get",
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {

                }
            ]
        }
    )


def test_root_token_jessica(client: TestClient):
    response = client.get("/?token=jessica")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello Bigger Applications!"}


def test_root_with_no_token(client: TestClient):
    response = client.get("/")
    assert response.status_code == 422

                }
            ]
        }
    )


@needs_py39
def test_root_token_jessica(client: TestClient):
    response = client.get("/?token=jessica")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello Bigger Applications!"}


@needs_py39
def test_root_with_no_token(client: TestClient):
    response = client.get("/")
    assert response.status_code == 422

## Przykład

### Stwórz

* Utwórz plik o nazwie `main.py` z:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

### Создание

* Создайте файл `main.py` со следующим содержимым:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

## Esempio

### Crea un file

* Crea un file `main.py` con:

```Python
from fastapi import FastAPI
from typing import Optional

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = Optional[None]):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

</div>

## 示例

### 创建

* 创建一个 `main.py` 文件并写入以下内容:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

## Резюме

* Импортируем `FastAPI`.
* Создаём экземпляр `app`.
* Пишем **декоратор операции пути** (такой как `@app.get("/")`).
* Пишем **функцию операции пути** (`def root(): ...`).

* Importieren Sie `FastAPI`.
* Erstellen Sie eine `app` Instanz.
* Schreiben Sie einen **Pfadoperation-Dekorator** (wie z. B. `@app.get("/")`).
* Schreiben Sie eine **Pfadoperation-Funktion** (wie z. B. oben `def root(): ...`).