Python: PonyORM设计精巧的ORM框架

Pony is an advanced object-relational mapper

文档：

• PyPI: https://pypi.org/project/pony/
• Github: https://github.com/ponyorm/pony
• doc: https://docs.ponyorm.org/

安装

pip install pony

代码实例

# -*- coding: utf-8 -*-
from pony.orm import Database, db_session, Required, Set, select, set_sql_debug

# 创建数据库对象
db = Database()

# 建立数据库连接
db.bind(provider='sqlite', filename=':memory:')

# 开启debug,打印sql
set_sql_debug(True)

# 建立实体类
class Person(db.Entity):
    name = Required(str)
    age = Required(int)
    cars = Set('Car')


class Car(db.Entity):
    make = Required(str)
    model = Required(str)
    owner = Required(Person)


# 建表
db.generate_mapping(create_tables=True)


"""
CREATE TABLE "Person" (
  "id" INTEGER PRIMARY KEY AUTOINCREMENT,
  "name" TEXT NOT NULL,
  "age" INTEGER NOT NULL
)

CREATE TABLE "Car" (
  "id" INTEGER PRIMARY KEY AUTOINCREMENT,
  "make" TEXT NOT NULL,
  "model" TEXT NOT NULL,
  "owner" INTEGER NOT NULL REFERENCES "Person" ("id") ON DELETE CASCADE
)

SELECT "Car"."id", "Car"."make", "Car"."model", "Car"."owner"
FROM "Car" "Car"
WHERE 0 = 1

SELECT "Person"."id", "Person"."name", "Person"."age"
FROM "Person" "Person"
WHERE 0 = 1

"""

# 插入数据
with db_session:
    p1 = Person(name='John', age=20)
    p2 = Person(name='Mary', age=22)
    p3 = Person(name='Bob', age=30)
    c1 = Car(make='Toyota', model='Prius', owner=p2)
    c2 = Car(make='Ford', model='Explorer', owner=p3)
"""
INSERT INTO "Person" ("name", "age") VALUES (?, ?)
['John', 20]

INSERT INTO "Person" ("name", "age") VALUES (?, ?)
['Mary', 22]

INSERT INTO "Person" ("name", "age") VALUES (?, ?)
['Bob', 30]

INSERT INTO "Car" ("make", "model", "owner") VALUES (?, ?, ?)
['Toyota', 'Prius', 2]

INSERT INTO "Car" ("make", "model", "owner") VALUES (?, ?, ?)
['Ford', 'Explorer', 3]
"""


# 更新数据
with db_session:
    p = Person.get(id=2)  # 使用get来获取一条数据，如果没有查到会返回None
    p.name = "new name"

"""
SELECT "id", "name", "age"
FROM "Person"
WHERE "id" = ?
[2]

UPDATE "Person"
SET "name" = ?
WHERE "id" = ?
['new name', 2]
"""
# 查询数据
with db_session:
    for person in select(p for p in Person if p.age > 20)[:]:
        print(person.name, person.age, person.cars)

"""
SELECT "p"."id", "p"."name", "p"."age"
FROM "Person" "p"
WHERE "p"."age" > 20

SELECT "id", "make", "model", "owner"
FROM "Car"
WHERE "owner" = ?
[2]


SELECT "id", "make", "model", "owner"
FROM "Car"
WHERE "owner" = ?
[3]
"""

参考
只有 Python 魔法少女才知道的 PonyORM
抛弃丑陋，拥抱优雅–Pythonic的Pony ORM