from contextvars import ContextVar

import peewee

DATABASE_NAME = "test.db"
db_state_default = {"closed": None, "conn": None, "ctx": None, "transactions": None}
db_state = ContextVar("db_state", default=db_state_default.copy())


class PeeweeConnectionState(peewee._ConnectionState):
    def __init__(self, **kwargs):
        super().__setattr__("_state", db_state)
        super().__init__(**kwargs)

    def __setattr__(self, name, value):

它可能有一个像`"Arquilian"`(一种业务逻辑)。

当您尝试从您的宠物对象访问它时，ORM 将完成所有工作以从相应的表*所有者那里再获取信息。*

常见的 ORM 例如：Django-ORM（Django 框架的一部分）、SQLAlchemy ORM（SQLAlchemy 的一部分，独立于框架）和 Peewee（独立于框架）等。

在这里，我们将看到如何使用**SQLAlchemy ORM**。

以类似的方式，您也可以使用任何其他 ORM。

!!! tip
    在文档中也有一篇使用 Peewee 的等效的文章。

## 文件结构

对于这些示例，假设您有一个名为的目录`my_super_project`，其中包含一个名为的子目录`sql_app`，其结构如下：

```
.
└── sql_app
    ├── __init__.py
    ├── crud.py

* Fix Peewee `contextvars` handling in docs: [SQL (Relational) Databases with Peewee](https://fastapi.tiangolo.com/advanced/sql-databases-peewee/). PR [#879](https://github.com/tiangolo/fastapi/pull/879).

If you already have a code base that uses <a href="https://docs.peewee-orm.com/en/latest/" class="external-link" target="_blank">Peewee ORM</a>, you can check here how to use it with **FastAPI**.

!!! warning "Python 3.7+ required"
    You will need Python 3.7 or above to safely use Peewee with FastAPI.

## Peewee for async

Peewee was not designed for async frameworks, or with them in mind.

    - sponsors_badge: ../en/data/sponsors_badge.yml
    - sponsors: ../en/data/sponsors.yml
  redirects:
    redirect_maps:
      deployment/deta.md: deployment/cloud.md
      advanced/sql-databases-peewee.md: how-to/sql-databases-peewee.md
      advanced/async-sql-databases.md: how-to/async-sql-encode-databases.md
      advanced/nosql-databases.md: how-to/nosql-databases-couchbase.md
      advanced/graphql.md: how-to/graphql.md

import peewee

from .database import db


class User(peewee.Model):
    email = peewee.CharField(unique=True, index=True)
    hashed_password = peewee.CharField()
    is_active = peewee.BooleanField(default=True)

    class Meta:
        database = db


class Item(peewee.Model):
    title = peewee.CharField(index=True)
    description = peewee.CharField(index=True)
    owner = peewee.ForeignKeyField(User, backref="items")

!!! note "📡 ℹ"
    👆 💪 ✍ 🌅 🔃 🏒 🧍 🔃 🔁 🐍 <a href="https://docs.peewee-orm.com/en/latest/peewee/database.html#async-with-gevent" class="external-link" target="_blank">🩺</a>, <a href="https://github.com/coleifer/peewee/issues/263#issuecomment-517347032" class="external-link" target="_blank">❔</a>, <a href="https://github.com/coleifer/peewee/pull/2072#issuecomment-563215132" class="external-link" target="_blank">🇵🇷</a>.

## 🎏 📱

from typing import Any, List, Union

import peewee
from pydantic import BaseModel
from pydantic.utils import GetterDict


class PeeweeGetterDict(GetterDict):
    def get(self, key: Any, default: Any = None):
        res = getattr(self._obj, key, default)
        if isinstance(res, peewee.ModelSelect):
            return list(res)
        return res


class ItemBase(BaseModel):
    title: str
    description: Union[str, None] = None

Common ORMs are for example: Django-ORM (part of the Django framework), SQLAlchemy ORM (part of SQLAlchemy, independent of framework) and Peewee (independent of framework), among others.

Here we will see how to work with **SQLAlchemy ORM**.

In a similar way you could use any other ORM.

!!! tip
    There's an equivalent article using Peewee here in the docs.

## File structure