{!../../docs_src/bigger_applications/app/routers/items.py!}
```

Como o caminho de cada *operação de rota* deve começar com `/`, como em:

```Python hl_lines="1"
@router.get("/{item_id}")
async def read_item(item_id: str):
    ...
```

...o prefixo não deve incluir um `/` final.

Então, o prefixo neste caso é `/items`.

```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}
```

### Dockerfile

Now in the same project directory create a file `Dockerfile` with:

```{ .dockerfile .annotate }

{!../../docs_src/bigger_applications/app/routers/items.py!}
```

由于每个*路径操作*的路径都必须以 `/` 开头，例如：

```Python hl_lines="1"
@router.get("/{item_id}")
async def read_item(item_id: str):
    ...
```

...前缀不能以 `/` 作为结尾。

因此，本例中的前缀为 `/items`。

我们还可以添加一个 `tags` 列表和额外的 `responses` 列表，这些参数将应用于此路由器中包含的所有*路径操作*。

```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}
```

### Dockerfile

В этой же директории создайте файл `Dockerfile` и заполните его:

```{ .dockerfile .annotate }

```Python
from typing import Optional

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}
```

### Dockerfile

Agora, no mesmo diretório do projeto, crie um arquivo `Dockerfile` com:

```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}
```

### Dockerfile

Erstellen Sie nun im selben Projektverzeichnis eine Datei `Dockerfile` mit:

```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}
```

### Dockerfile

现在在相同的project目录创建一个名为`Dockerfile`的文件:

```{ .dockerfile .annotate }
# (1)
FROM python:3.9

```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}
```

### 도커파일

이제 같은 프로젝트 디렉터리에 다음과 같은 파일 `Dockerfile`을 생성합니다:

```{ .dockerfile .annotate }
# (1)

```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}
```

### Dockerfile

同じプロジェクト・ディレクトリに`Dockerfile`というファイルを作成します：

```{ .dockerfile .annotate }
# (1)