Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001.py!}
    ```

!!! warning
    Notice that `Field` is imported directly from `pydantic`, not from `fastapi` as are all the rest (`Query`, `Path`, `Body`, etc).

## Declare model attributes

You can then use `Field` with model attributes:

=== "Python 3.10+"

    ```Python hl_lines="11-14"

You can use the same dependency overrides from [Testing Dependencies with Overrides](testing-dependencies.md){.internal-link target=_blank} to alter a database for testing.

In the docs UI at <a href="http://127.0.0.1:9999/api/v1/docs" class="external-link" target="_blank">http://127.0.0.1:9999/api/v1/docs</a> it would look like:

<img src="/img/tutorial/behind-a-proxy/image03.png">

!!! tip
    The docs UI will interact with the server that you select.

### Disable automatic server from `root_path`

### Preprocess the OpenAPI Specification for the Client Generator

The generated code still has some **duplicated information**.

We already know that this method is related to the **items** because that word is in the `ItemsService` (taken from the tag), but we still have the tag name prefixed in the method name too. 😕

## `Request` 文档

更多细节详见 <a href="https://www.starlette.io/requests/" class="external-link" target="_blank">Starlette 官档 - `Request` 对象</a>。

!!! note "技术细节"

    您也可以使用 `from starlette.requests import Request`。

You can combine `dataclasses` with other type annotations in many different combinations to form complex data structures.

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.

Dichiara il _body_ usando le annotazioni di tipo standard di Python, grazie a Pydantic.

```Python hl_lines="2  7-10  23-25"
from fastapi import FastAPI
from pydantic import BaseModel
from typing import Optional

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool = Optional[None]


@app.get("/")

```{ .dockerfile .annotate }
# (1)
FROM python:3.9 as requirements-stage

# (2)
WORKDIR /tmp

# (3)
RUN pip install poetry

# (4)
COPY ./pyproject.toml ./poetry.lock* /tmp/

# (5)
RUN poetry export -f requirements.txt --output requirements.txt --without-hashes

# (6)
FROM python:3.9

# (7)
WORKDIR /code

# (8)

<font color="#3465A4">INFO    </font> Searching for package file structure from directories with <font color="#3465A4">__init__.py</font> files
<font color="#3465A4">INFO    </font> Importing from <font color="#75507B">/home/user/code/</font><font color="#AD7FA8">awesomeapp</font>

 ╭─ <font color="#8AE234"><b>Python module file</b></font> ─╮
 │                      │

    , 👆 🔜 ✔️ ⚒ 💭 👆 💽 ☑ 🆎. 🤶 Ⓜ. ⚫️ 🔗 ⏮️ 🎻, 🚥 👆 🛬 `JSONResponse`.

     & 👈 👆 🚫 📨 🙆 📊 👈 🔜 ✔️ ⛽ `response_model`.

### 🌅 ℹ

!!! note "📡 ℹ"
    👆 💪 ⚙️ `from starlette.responses import Response` ⚖️ `from starlette.responses import JSONResponse`.

    **FastAPI** 🚚 🎏 `starlette.responses` `fastapi.responses` 🏪 👆, 👩‍💻. ✋️ 🌅 💪 📨 👟 🔗 ⚪️➡️ 💃.