```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

In this case, `item_id` is declared to be an `int`.

!!! check
    This will give you editor support inside of your function, with error checks, completion, etc.

## Data <abbr title="also known as: serialization, parsing, marshalling">conversion</abbr>

These features are what Marshmallow was built to provide. It is a great library, and I have used it a lot before.

But it was created before there existed Python type hints. So, to define every <abbr title="the definition of how data should be formed">schema</abbr> you need to use specific utils and classes provided by Marshmallow.

!!! check "Inspired **FastAPI** to"

#!/usr/bin/env bash

set -e
set -x

mypy fastapi
ruff check fastapi tests docs_src scripts

⚫️ ⚙️ 📚 🏢 ✅ 🦎, 🟥 👒 & 🎟.

⚫️ 🕐 🥇 🖼 **🏧 🛠️ 🧾**, & 👉 🎯 🕐 🥇 💭 👈 😮 "🔎" **FastAPI**.

!!! note
    ✳ 🎂 🛠️ ✍ ✡ 🇺🇸🏛. 🎏 👼 💃 & Uvicorn, 🔛 ❔ **FastAPI** ⚓️.


!!! check "😮 **FastAPI** "
    ✔️ 🏧 🛠️ 🧾 🕸 👩‍💻 🔢.

### <a href="https://flask.palletsprojects.com" class="external-link" target="_blank">🏺</a>

🏺 "🕸", ⚫️ 🚫 🔌 💽 🛠️ 🚫 📚 👜 👈 👟 🔢 ✳.

FastAPI will use this `response_model` to do all the data documentation, validation, etc. and also to **convert and filter the output data** to its type declaration.

!!! tip
    If you have strict type checks in your editor, mypy, etc, you can declare the function return type as `Any`.

Check the in-code annotation tips above to see more specific details.

## Learn More

You can also combine `dataclasses` with other Pydantic models, inherit from them, include them in your own models, etc.

Вы можете объявить тип параметра пути в функции, используя стандартные аннотации типов Python.

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

Здесь, `item_id` объявлен типом `int`.

!!! check "Заметка"
    Это обеспечит поддержку редактора внутри функции (проверка ошибок, автодополнение и т.п.).

## <abbr title="Или сериализация, парсинг">Преобразование</abbr> данных

{!../../../docs_src/path_params/tutorial002.py!}
```

本例把 `item_id` 的类型声明为 `int`。

!!! check "检查"

    类型声明将为函数提供错误检查、代码补全等编辑器支持。

## 数据<abbr title="也称为：序列化、解析">转换</abbr>

运行示例并访问 <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>，返回的响应如下：

```JSON
{"item_id":3}
```

!!! check "检查"

    注意，函数接收并返回的值是 `3`（ `int`），不是 `"3"`（`str`）。

### Check the docs UI

But here's the fun part. ✨

The "official" way to access the app would be through the proxy with the path prefix that we defined. So, as we would expect, if you try the docs UI served by Uvicorn directly, without the path prefix in the URL, it won't work, because it expects to be accessed through the proxy.

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

Ici, `item_id` est déclaré comme `int`.

!!! check "vérifier"
    Ceci vous permettra d'obtenir des fonctionnalités de l'éditeur dans votre fonction, telles
    que des vérifications d'erreur, de l'auto-complétion, etc.