Many packages that simplify it a lot have to make many compromises with the data model, database, and available features. And some of these packages that simplify things too much actually have security flaws underneath.

---

**FastAPI** doesn't make any compromise with any database, data model or tool.

It gives you all the flexibility to choose the ones that fit your project the best.

```

### ✍ ⏲ *➡ 🛠️*

✍ ⏲ *➡ 🛠️* ⚙️ 🎏 `APIRouter` 👆 ✍ 🔛.

⚫️ 🔜 👀 💖 😐 FastAPI *➡ 🛠️*:

* ⚫️ 🔜 🎲 ✔️ 📄 💪 ⚫️ 🔜 📨, ✅ `body: InvoiceEvent`.
*  & ⚫️ 💪 ✔️ 📄 📨 ⚫️ 🔜 📨, ✅ `response_model=InvoiceEventReceived`.

```Python hl_lines="16-18  21-22  28-32"
{!../../../docs_src/openapi_callbacks/tutorial001.py!}
```

📤 2️⃣ 👑 🔺 ⚪️➡️ 😐 *➡ 🛠️*:

<img src="/img/tutorial/generate-clients/image03.png">

!!! tip
    Notice the autocompletion for `name` and `price`, that was defined in the FastAPI application, in the `Item` model.

You will have inline errors for the data that you send:

<img src="/img/tutorial/generate-clients/image04.png">

The response object will also have autocompletion:

!!! info
    ✔️ 🤯 👈 🎻 💪 🚫 🌐 Pydantic 🏷 💪.

    , 👆 5️⃣📆 💪 ⚙️ Pydantic 🏷.

    ✋️ 🚥 👆 ✔️ 📚 🎻 🤥 🤭, 👉 👌 🎱 ⚙️ 👫 🏋️ 🕸 🛠️ ⚙️ FastAPI. 👶

## 🎻 `response_model`

👆 💪 ⚙️ `dataclasses` `response_model` 🔢:

```Python hl_lines="1  7-13  19"
{!../../../docs_src/dataclasses/tutorial002.py!}
```

🎻 🔜 🔁 🗜 Pydantic 🎻.

👉 🌌, 🚮 🔗 🔜 🎦 🆙 🛠️ 🩺 👩‍💻 🔢:

`RequestValidationError` 🎧-🎓 Pydantic <a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a>.

**FastAPI** ⚙️ ⚫️ 👈, 🚥 👆 ⚙️ Pydantic 🏷 `response_model`, &amp; 👆 💽 ✔️ ❌, 👆 🔜 👀 ❌ 👆 🕹.

✋️ 👩‍💻/👩‍💻 🔜 🚫 👀 ⚫️. ↩️, 👩‍💻 🔜 📨 "🔗 💽 ❌" ⏮️ 🇺🇸🔍 👔 📟 `500`.

⚫️ 🔜 👉 🌌 ↩️ 🚥 👆 ✔️ Pydantic `ValidationError` 👆 *📨* ⚖️ 🙆 👆 📟 (🚫 👩‍💻 *📨*), ⚫️ 🤙 🐛 👆 📟.

]

[tool.coverage.run]
parallel = true
source = [
    "docs_src",
    "tests",
    "fastapi"
]
context = '${CONTEXT}'
omit = [
    "docs_src/response_model/tutorial003_04.py",
    "docs_src/response_model/tutorial003_04_py310.py",
]

[tool.ruff.lint]
select = [
    "E",  # pycodestyle errors
    "W",  # pycodestyle warnings
    "F",  # pyflakes
    "I",  # isort

```Python hl_lines="17"
{!../../../docs_src/path_params/tutorial005.py!}
```

#### *Enum-Wert* erhalten

Den tatsächlichen Wert (in diesem Fall ein `str`) erhalten Sie via `model_name.value`, oder generell, `ihr_enum_member.value`:

```Python hl_lines="20"
{!../../../docs_src/path_params/tutorial005.py!}
```

!!! tip "Tipp"

数据类的和运作方式与 Pydantic 模型相同。实际上，它的底层使用的也是 Pydantic。

!!! info "说明"

    注意，数据类不支持 Pydantic 模型的所有功能。

    因此，开发时仍需要使用 Pydantic 模型。

    但如果数据类很多，这一技巧能给 FastAPI 开发 Web API 增添不少助力。🤓

## `response_model` 使用数据类

在 `response_model` 参数中使用 `dataclasses`：

```Python hl_lines="1  7-13  19"
{!../../../docs_src/dataclasses/tutorial002.py!}
```

本例把数据类自动转换为 Pydantic 数据类。

API 文档中也会显示相关概图：

`RequestValidationError`はPydanticの<a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a>のサブクラスです。

**FastAPI** は`response_model`でPydanticモデルを使用していて、データにエラーがあった場合、ログにエラーが表示されるようにこれを使用しています。

しかし、クライアントやユーザーはそれを見ることはありません。その代わりに、クライアントはHTTPステータスコード`500`の「Internal Server Error」を受け取ります。

And if you declared a `response_model`, it will still be used to filter and convert the object you returned.

**FastAPI** will use that *temporal* response to extract the headers (also cookies and status code), and will put them in the final response that contains the value you returned, filtered by any `response_model`.