peewee README

The project's README from github.com/coleifer/peewee. As one markdown file: README.md.

.. image:: https://media.charlesleifer.com/blog/photos/peewee4-logo.png

peewee

Peewee is a simple and small ORM. It has few (but expressive) concepts, making it easy to learn and intuitive to use.

Peewee is a single module with no required dependencies and has been running production workloads of all sizes since 2010.

New to peewee? These may help:

Installation:

.. code-block:: console

pip install peewee

Sqlite comes built-in provided by the standard-lib sqlite3 module. Other backends can be installed using the following instead:

.. code-block:: console

pip install peewee[mysql]  # Install peewee with pymysql.
pip install peewee[postgres]  # Install peewee with psycopg2.
pip install peewee[psycopg3]  # Install peewee with psycopg3.

# AsyncIO implementations.
pip install peewee[aiosqlite]  # Install peewee with aiosqlite.
pip install peewee[aiomysql]  # Install peewee with aiomysql.
pip install peewee[asyncpg]  # Install peewee with asyncpg.

Examples

Defining models is similar to Django or SQLAlchemy:

.. code-block:: python

from peewee import *
import datetime


db = SqliteDatabase('my_database.db')

class BaseModel(Model):
    class Meta:
        database = db

class User(BaseModel):
    username = CharField(unique=True)

class Tweet(BaseModel):
    user = ForeignKeyField(User, backref='tweets')
    message = TextField()
    created_date = DateTimeField(default=datetime.datetime.now)
    is_published = BooleanField(default=True)

Connect to the database and create tables:

.. code-block:: python

db.connect()
db.create_tables([User, Tweet])

Create a few rows:

.. code-block:: python

charlie = User.create(username='charlie')
huey = User(username='huey')
huey.save()

# No need to set `is_published` or `created_date` since they
# will just use the default values we specified.
Tweet.create(user=charlie, message='My first tweet')

Queries are expressive and composable:

.. code-block:: python

# A simple query selecting a user.
User.get(User.username == 'charlie')

# Get tweets created by one of several users.
usernames = ['charlie', 'huey', 'mickey']
users = User.select().where(User.username.in_(usernames))
tweets = Tweet.select().where(Tweet.user.in_(users))

# We could accomplish the same using a JOIN:
tweets = (Tweet
          .select()
          .join(User)
          .where(User.username.in_(usernames)))

# How many tweets were published today?
tweets_today = (Tweet
                .select()
                .where(
                    (Tweet.created_date >= datetime.date.today()) &
                    (Tweet.is_published == True))
                .count())

# Paginate the user table and show me page 3 (users 41-60).
User.select().order_by(User.username).paginate(3, 20)

# Order users by the number of tweets they've created:
tweet_ct = fn.Count(Tweet.id)
users = (User
         .select(User, tweet_ct.alias('ct'))
         .join(Tweet, JOIN.LEFT_OUTER)
         .group_by(User)
         .order_by(tweet_ct.desc()))

# Do an atomic update (for illustrative purposes only, imagine a simple
# table for tracking a "count" associated with each URL). We don't want to
# naively get the save in two separate steps since this is prone to race
# conditions.
Counter.update(count=Counter.count + 1).where(Counter.url == request.url).execute()

Check out the example twitter app <http://docs.peewee-orm.com/en/latest/peewee/example.html>_.

Asyncio

.. code-block:: python

import asyncio
from peewee import *
from playhouse.pwasyncio import AsyncPostgresqlDatabase

db = AsyncPostgresqlDatabase('my_app')

class User(db.Model):
    username = CharField(unique=True)

class Tweet(db.Model):
    user = ForeignKeyField(User, backref='tweets')
    message = TextField()

async def main():
    async with db:
        await db.acreate_tables([User, Tweet])

        # Queries are awaited on the event loop using asyncpg.
        huey = await User.acreate(username='huey')
        tweet = await Tweet.acreate(user=huey, message='meow')

        async with db.atomic():
            tweet.message = 'purr'
            await tweet.asave()

        # Create a query - nothing is executed yet.
        query = Tweet.select(Tweet, User).join(User)

        # Execute and buffer the results.
        tweets = await query.aexecute()  # Or: await db.list(query)
        for tweet in tweets:
            print(tweet.user.username, '->', tweet.message)

        # Streaming results via server-side cursor.
        async for tweet in db.iterate(query):
            print(tweet.user.username, '->', tweet.message)

    await db.close_pool()

asyncio.run(main())

See the asyncio docs <https://docs.peewee-orm.com/en/latest/peewee/asyncio.html>_ for details.

Learning more

Check the documentation <http://docs.peewee-orm.com/>_ for more examples.

Specific question? Come hang out in the #peewee channel on irc.libera.chat, or post to the mailing list, http://groups.google.com/group/peewee-orm . If you would like to report a bug, create a new issue <https://github.com/coleifer/peewee/issues/new>_ on GitHub.

Still want more info?

.. image:: https://media.charlesleifer.com/blog/photos/wat.jpg

I've written a number of blog posts about building applications and web-services with peewee (and usually Flask). If you'd like to see some real-life applications that use peewee, the following resources may be useful:

peewee (coleifer/peewee)

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12K ·GitHub
这是什么?Peewee 是一个小巧、表达力强的 Python ORM(对象关系映射),让你可以用 Python 对象来操作 SQL 数据库,并使用灵活的查询构建器。
它是框架还是普通库?它是一个单模块库,导入到你的应用中即可使用,而不是框架。它没有必需的依赖项,并且可以接入 Flask 或 FastAPI 等现有框架。
怎样把它添加到项目中?将它作为 Python 包安装,然后把你的模型定义为映射到数据库表的类,再使用查询构建器 API 来查询、插入、更新和删除数据行。
它支持哪些数据库?还需要额外的驱动程序吗?开箱即支持 SQLite、MySQL、MariaDB 和 PostgreSQL;核心库不需要任何必需的第三方依赖。
它开箱即支持 async/await 吗?支持。peewee 提供 asyncio 支持,可以通过服务端游标对查询结果进行异步迭代,同时仍保留常规的同步 API。
这个库适合谁用?适合正在开发 Web 应用或服务(常与 Flask 或 FastAPI 搭配)的 Python 开发者,尤其是那些想要比 SQLAlchemy 或 Django ORM 这类更重的方案更轻量的 ORM 的人。
我能做原子更新来避免竞态条件吗?可以。你可以直接在 SQL 中执行原子更新,例如在单条更新语句中递增计数器字段,从而避免先读后写导致的竞态条件。
它支持分页和排序辅助方法吗?支持。查询结果支持可链式调用的方法,如 .orderby() 和 .paginate(),便于轻松排序并翻页浏览大量结果。
有没有可以用来学习的真实示例应用?有。README 中提到了一个类似 Twitter 的示例应用,以及几篇博客文章,展示了 peewee 与 Flask 搭配用于笔记应用、书签服务等场景。
What are similar projects?sequelize, efcore, diesel, typeorm, orm, ent, drizzle-orm, sqlmodel
Creator
coleifer
Size
17.1 MB
Stars
12K
Age
16y
Commits · 90 Days