When using **Pydantic v2**, the generated OpenAPI is a bit more exact and **correct** than before. 😎

In fact, in some cases, it will even have **two JSON Schemas** in OpenAPI for the same Pydantic model, for input and output, depending on if they have **default values**.

Let's see how that works and how to change it if you need to do that.

## Pydantic Models for Input and Output

from datetime import datetime, timezone

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

from .utils import needs_pydanticv1, needs_pydanticv2


@needs_pydanticv2
def test_pydanticv2():
    from pydantic import field_serializer

    class ModelWithDatetimeField(BaseModel):
        dt_field: datetime

        @field_serializer("dt_field")

PyGithub>=2.3.0,<3.0.0
pydantic>=2.5.3,<3.0.0
pydantic-settings>=2.1.0,<3.0.0
httpx>=0.27.0,<0.28.0

## Sobre Pydantic

Pydantic incluí os testes para **FastAPI** em seus próprios testes, então as novas versões de Pydantic (acima da `1.0.0`) sempre serão compatíveis com FastAPI.

Você pode fixar qualquer versão de Pydantic que desejar, desde que seja acima da `1.0.0` e abaixo da `2.0.0`.

Por exemplo:

```txt
pydantic>=1.2.0,<2.0.0

## 特殊な型とバリデーション

`str`や`int`、`float`のような通常の単数型の他にも、`str`を継承したより複雑な単数型を使うこともできます。

すべてのオプションをみるには、<a href="https://docs.pydantic.dev/latest/concepts/types/" class="external-link" target="_blank">Pydanticのエキゾチック な型</a>のドキュメントを確認してください。次の章でいくつかの例をみることができます。

例えば、`Image`モデルのように`url`フィールドがある場合、`str`の代わりにPydanticの`HttpUrl`を指定することができます:

```Python hl_lines="4 10"
{!../../docs_src/body_nested_models/tutorial005.py!}
```

## Məcburi Olmayan Tələblər

Pydantic tərəfindən istifadə olunanlar:

* <a href="https://github.com/JoshData/python-email-validator" target="_blank"><code>email-validator</code></a> - e-poçtun yoxlanılması üçün.
* <a href="https://docs.pydantic.dev/latest/usage/pydantic_settings/" target="_blank"><code>pydantic-settings</code></a> - parametrlərin idarə edilməsi üçün.

                                ],
                            }
                        )
                        | IsDict(
                            # TODO: remove when deprecating Pydantic v1
                            {
                                "title": "Grant Type",
                                "pattern": "password",
                                "type": "string",

                                    }
                                )
                                | IsDict(
                                    # TODO: remove when deprecating Pydantic v1
                                    {
                                        "$ref": "#/components/schemas/Body_create_file_files__post"
                                    }
                                )

                                    }
                                )
                                | IsDict(
                                    # TODO: remove when deprecating Pydantic v1
                                    {
                                        "$ref": "#/components/schemas/Body_create_file_files__post"
                                    }
                                )

## À propos de Pydantic

Pydantic inclut des tests pour **FastAPI** avec ses propres tests, ainsi les nouvelles versions de Pydantic (au-dessus
de `1.0.0`) sont toujours compatibles avec **FastAPI**.

Vous pouvez épingler Pydantic à toute version supérieure à `1.0.0` qui fonctionne pour vous et inférieure à `2.0.0`.

Par exemple :

```txt
pydantic>=1.2.0,<2.0.0