### Type Annotations and Tooling

First let's see how editors, mypy and other tools would see this.

`BaseUser` has the base fields. Then `UserIn` inherits from `BaseUser` and adds the `password` field, so, it will include all the fields from both models.

We annotate the function return type as `BaseUser`, but we are actually returning a `UserIn` instance.

    _get_model_config,
    is_bytes_sequence_annotation,
    is_uploadfile_sequence_annotation,
)
from fastapi.testclient import TestClient
from pydantic import BaseConfig, BaseModel, ConfigDict
from pydantic.fields import FieldInfo

from .utils import needs_pydanticv1, needs_pydanticv2


@needs_pydanticv2
def test_model_field_default_required():
    # For coverage
    field_info = FieldInfo(annotation=str)

!!! tip
    Pydantic, ❔ ⚫️❔ 🏋️ 🌐 💽 🔬 &amp; 🛠️ FastAPI, ✔️ 🎁 🎭 🕐❔ 👆 ⚙️ `Optional` ⚖️ `Union[Something, None]` 🍵 🔢 💲, 👆 💪 ✍ 🌅 🔃 ⚫️ Pydantic 🩺 🔃 <a href="https://docs.pydantic.dev/latest/concepts/models/#required-optional-fields" class="external-link" target="_blank">✔ 📦 🏑</a>.

### ⚙️ Pydantic `Required` ↩️ ❕ (`...`)

🚥 👆 💭 😬 ⚙️ `...`, 👆 💪 🗄 &amp; ⚙️ `Required` ⚪️➡️ Pydantic:

```Python hl_lines="2  8"

import warnings
from enum import Enum
from typing import Any, Callable, Dict, List, Optional, Sequence, Union

from fastapi.openapi.models import Example
from pydantic.fields import FieldInfo
from typing_extensions import Annotated, deprecated

from ._compat import PYDANTIC_V2, PYDANTIC_VERSION, Undefined

_Unset: Any = Undefined


class ParamTypes(Enum):
    query = "query"
    header = "header"
    path = "path"

It can't handle nested models very well. So, if the JSON body in the request is a JSON object that has inner fields that in turn are nested JSON objects, it cannot be properly documented and validated.

!!! check "Inspired **FastAPI** to"
    Use Python types to have great editor support.

**Spoiler alert**: il tutorial - Guida Utente include:

* Dichiarazione di **parameters** da altri posti diversi come: **headers**, **cookies**, **form fields** e **files**.
* Come stabilire **vincoli di validazione** come `maximum_length` o `regex`.

=== "Python 3.10+"

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001_an.py!}
    ```

=== "Python 3.10+ Annotated가 없는 경우"

    !!! tip "팁"

まず、以下のようにインポートします:

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

!!! warning "注意"
    `Field`は他の全てのもの（`Query`、`Path`、`Body`など）とは違い、`fastapi`からではなく、`pydantic`から直接インポートされていることに注意してください。

## モデルの属性の宣言

以下のように`Field`をモデルの属性として使用することができます:

```Python hl_lines="11 12 13 14"
{!../../../docs_src/body_fields/tutorial001.py!}
```

`Field`は`Query`や`Path`、`Body`と同じように動作し、全く同様のパラメータなどを持ちます。

### Changes

* There are **new parameter** fields supported by Pydantic `Field()` for:

    * `Path()`
    * `Query()`
    * `Header()`
    * `Cookie()`
    * `Body()`
    * `Form()`
    * `File()`

* The new parameter fields are:

    * `default_factory`
    * `alias_priority`
    * `validation_alias`

    ```

The files and form fields will be uploaded as form data and you will receive the files and form fields.

And you can declare some of the files as `bytes` and some as `UploadFile`.

!!! warning