### Pydantic v1 `regex` instead of `pattern`

Before Pydantic version 2 and before FastAPI 0.100.0, the parameter was called `regex` instead of `pattern`, but it's now deprecated.

You could still see some code using it:

//// tab | Python 3.10+ Pydantic v1

```Python hl_lines="11"

## Yêu cầu

FastAPI đứng trên vai những người khổng lồ:

* <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> cho phần web.
* <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> cho phần data.

## Cài đặt

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

## 依赖

Python 及更高版本

FastAPI 站在以下巨人的肩膀之上：

* <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> 负责 web 部分。
* <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> 负责数据部分。

## 安装

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

{!> ../../docs_src/response_model/tutorial001.py!}
```

////

/// note

注意，`response_model`是「装饰器」方法（`get`，`post` 等）的一个参数。不像之前的所有参数和请求体，它不属于*路径操作函数*。

///

它接收的类型与你将为 Pydantic 模型属性所声明的类型相同，因此它可以是一个 Pydantic 模型，但也可以是一个由 Pydantic 模型组成的 `list`，例如 `List[Item]`。

FastAPI 将使用此 `response_model` 来：

* 将输出数据转换为其声明的类型。
* 校验数据。
* 在 OpenAPI 的*路径操作*中为响应添加一个 JSON Schema。
* 并在自动生成文档系统中使用。

但最重要的是：

## Àṣàyàn Àwọn Àfikún Ìgbẹ́kẹ̀lé Kóòdù

Èyí tí Pydantic ń lò:

* <a href="https://github.com/JoshData/python-email-validator" target="_blank"><code>email-validator</code></a> - fún ifọwọsi ímeèlì.
* <a href="https://docs.pydantic.dev/latest/usage/pydantic_settings/" target="_blank"><code>pydantic-settings</code></a> - fún ètò ìsàkóso.

## Full Stack FastAPI 템플릿 - 기술 스택과 기능들

- ⚡ [**FastAPI**](https://fastapi.tiangolo.com): Python 백엔드 API.
    - 🧰 [SQLModel](https://sqlmodel.tiangolo.com): Python SQL 데이터 상호작용을 위한 (ORM).
    - 🔍 [Pydantic](https://docs.pydantic.dev): FastAPI에 의해 사용되는, 데이터 검증과 설정관리.
    - 💾 [PostgreSQL](https://www.postgresql.org): SQL 데이터베이스.
- 🚀 [React](https://react.dev): 프론트엔드.
    - 💃 TypeScript, hooks, [Vite](https://vitejs.dev) 및 기타 현대적인 프론트엔드 스택을 사용.

/// info

Om meer te leren over <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic, bekijk de documentatie</a>.

///

**FastAPI** is volledig gebaseerd op Pydantic.

Je zult veel meer van dit alles in de praktijk zien in de [Tutorial - Gebruikershandleiding](tutorial/index.md){.internal-link target=_blank}.

/// tip

from fastapi.exceptions import ResponseValidationError
from fastapi.testclient import TestClient

from .utils import needs_pydanticv2


@pytest.fixture(name="client")
def get_client():
    from pydantic import BaseModel, ValidationInfo, field_validator

    app = FastAPI()

    class ModelB(BaseModel):
        username: str

    class ModelC(ModelB):
        password: str

    class ModelA(BaseModel):

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

                    "title": "Item",
                    "required": IsOneOf(
                        ["name", "description", "price", "tax", "tags"],
                        # TODO: remove when deprecating Pydantic v1
                        ["name", "price"],
                    ),
                    "type": "object",
                    "properties": {
                        "name": {"title": "Name", "type": "string"},