Then, you try with the old programmer's friend, editor autocompletion.

You type the first parameter of the function, `first_name`, then a dot (`.`) and then hit `Ctrl+Space` to trigger the completion.

But, sadly, you get nothing useful:

<img src="/img/python-types/image01.png">

### Add types

Let's modify a single line from the previous version.

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient


@pytest.fixture(name="client")
def get_client():
    from docs_src.bigger_applications.app_an.main import app

    client = TestClient(app)
    return client


def test_users_token_jessica(client: TestClient):
    response = client.get("/users?token=jessica")
    assert response.status_code == 200

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py39


@pytest.fixture(name="client")
def get_client():
    from docs_src.bigger_applications.app_an_py39.main import app

    client = TestClient(app)
    return client


@needs_py39
def test_users_token_jessica(client: TestClient):
    response = client.get("/users?token=jessica")

The response object will also have autocompletion:

<img src="/img/tutorial/generate-clients/image05.png">

## FastAPI App with Tags

In many cases your FastAPI app will be bigger, and you will probably use tags to separate different groups of *path operations*.

For example, you could have a section for **items** and another section for **users**, and they could be separated by tags:

```Python hl_lines="1  3" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

### *Path operations* with `APIRouter`

And then you use it to declare your *path operations*.

Use it the same way you would use the `FastAPI` class:

```Python hl_lines="6  11  16" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

你可以导入它并通过与 `FastAPI` 类相同的方式创建一个「实例」：

```Python hl_lines="1  3" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

### 使用 `APIRouter` 的*路径操作*

然后你可以使用它来声明*路径操作*。

使用方式与 `FastAPI` 类相同：

```Python hl_lines="6  11  16" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

你可以将 `APIRouter` 视为一个「迷你 `FastAPI`」类。

所有相同的选项都得到支持。

When building web APIs with FastAPI, if there's an error in our code, FastAPI will normally contain it to the single request that triggered the error. 🛡

The client will get a **500 Internal Server Error** for that request, but the application will continue working for the next requests instead of just crashing completely.

### Bigger Errors - Crashes

& ⤴️ `admin_email` ⚒ 🔜 ⚒ `"******@****.***"`.

`app_name` 🔜 `"ChimichangApp"`.

& `items_per_user` 🔜 🚧 🚮 🔢 💲 `50`.

## ⚒ ➕1️⃣ 🕹

👆 💪 🚮 👈 ⚒ ➕1️⃣ 🕹 📁 👆 👀 [🦏 🈸 - 💗 📁](../tutorial/bigger-applications.md){.internal-link target=_blank}.

🖼, 👆 💪 ✔️ 📁 `config.py` ⏮️:

```Python
{!../../../docs_src/settings/app01/config.py!}
```

& ⤴️ ⚙️ ⚫️ 📁 `main.py`:

```Dockerfile
FROM tiangolo/uvicorn-gunicorn-fastapi:python3.7

COPY ./app /app
```

#### Grandes aplicações

Se você seguiu a seção sobre criação de [Grandes Aplicações com Múltiplos Arquivos](tutorial/bigger-applications.md){.internal-link target=_blank}, seu `Dockerfile` poderia parecer como:

```Dockerfile
FROM tiangolo/uvicorn-gunicorn-fastapi:python3.7

COPY ./app /app/app
```

COPY ./requirements.txt /app/requirements.txt

RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt

COPY ./app /app
```

### 더 큰 어플리케이션

만약 여러분이 [다중 파일을 가지는 더 큰 어플리케이션](../tutorial/bigger-applications.md){.internal-link target=_blank}을 생성하는 섹션을 따랐다면, 여러분의 `Dockerfile`은 대신 이렇게 생겼을 것입니다:

```Dockerfile hl_lines="7"
FROM tiangolo/uvicorn-gunicorn-fastapi:python3.9