PyMyORM 1.1.0

Pure Python MySQL ORM

PyMyORM

Table of Contents

• Requirements
• Installation
• Documentation
• Example
• Resources
• License

This package contains a pure-Python MySQL Object Relational Mapping client library.

Requirements

• Python:
  • CPython: 3.6 or newer
  • PyMySQL: 0.9.0 or newer
• MySQL server -- one of the following:
  • MySQL >= 5.6
  • MariaDB >= 10.0

Installation

Package is uploaded on PyPI.

You can install it with pip:

$python3 pip install PyMyORM

Documentation

Documentation is coming soon.

Example

The following examples make use of a simple table

create table `t_user` (
    `id` int unsigned not null auto_increment,
    `name` varchar(16) not null default '',
    `phone` varchar(16) not null default '',
    `money` decimal(10,2) not null default 0,
    `gender` tinyint unsigned not null default 0,
    `status` tinyint unsigned not null default 0,
    `time` timestamp not null default current_timestamp,
    primary key(`id`),
    unique key `idx_name` (`name`),
    key `idx_phone` (`phone`),
    key `idx_status` (`status`),
    key `idx_time` (`time`)
) engine=InnoDB auto_increment=1 default charset=utf8mb4;

Model definition models/user.py

from pymyorm.model import Model

class User(Model):
    tablename = 't_user'

Connect to database

from pymyorm.database import Database
Database().connect(host='127.0.0.1',
                   port=3306,
                   user='root',
                   password='password',
                   database='test',
                   charset='utf8'
                   )

select

# case 1
from models.user import User
one = User.find().where(name='ping').one()
print(one.id, one.name)

# case 2
from models.user import User
one = User.find().select('name').where(name='ping').where(phone='18976641111').one()
print(one)

# case 3
from models.user import User
one = User.find().where(name='ping', phone='18976641111').one()
print(one)

# case 4
from models.user import User
one = User.find().where('money', '!=', 200).order('id desc').one()
print(one)

# case 6
from models.user import User
all = User.find().order('id desc').offset(0).limit(5).all()
for one in all:
    print(one)

where

we may filter data set by pass the where condition like below

from models.user import User
model = User.find()
if id:
    model.where(id=id)
if name:
    model.where(name=name)
if phone:
    model.where(phone=phone)
if status:
    model.where(status=status)

as you see, there are more if clause as conditions, it looks ugly. to enhance the code more readable, we can rewrite the code like this:

from models.user import User
model = User.find().where(id=id, name=name, phone=phone, status=status)

where function will auto ignore the empty value or None value.

update

# case 1
from models.user import User
one = User.find().where(name='lily').one()
one.money = 500
one.phone = '18976642222'
one.save()

# case 2
from models.user import User
User.find().where(name='lily').update(money=500, phone='18976642222')

insert

# case 1
from models.user import User
user = User(name='rose', phone='18976643333', money=100)
user.save()

# case 2
from models.user import User
user = User()
user.name = 'vera'
user.phone = '18976644444'
user.money = 100
user.save()

delete

# case 1
from models.user import User
one = User.find().where(name='lily').one()
one.delete()

# case 2
from models.user import User
User.find().where(money=100).delete()

# case 3
from models.user import User
all = User.find().select('name', 'phone').where('money', '>', 100).all()
for one in all:
    one.delete()

# case 4
from models.user import User
User.find().delete() # delete all users

exists

from models.user import User
exists = User.find().where(name='ping').exists()

count

from models.user import User
count = User.find().where(status='0').count()

min

from models.user import User
money = User.find().where(status=0).min('money')

max

from models.user import User
money = User.find().where(status=0).max('money')
print(money)

average

from models.user import User
money = User.find().where(status=0).average('money')

scalar

from models.user import User
money = User.find().where(id=1).scalar('money')

column

from models.user import User
names = User.find().column('name')

truncate

from models.user import User
User.find().truncate()

join

# case 1: inner join
from models.admin import Admin
from models.admin_role import AdminRole
all = Admin.find().select('a.*').alias('a') \
    .join(table=AdminRole.tablename, alias='r', on='a.role = r.id') \
    .where('r.name', '=', 'role1') \
    .where('a.lock', '=', 0) \
    .all()
for one in all:
    print(one)

# case 2: left join
from models.admin import Admin
from models.admin_role import AdminRole
all = Admin.find().alias('a') \
    .join(table=AdminRole.tablename, alias='r', on='a.role=r.id', type='left') \
    .where('a.lock', '=', 0) \
    .all()
for one in all:
    print(one)

# case 3
from models.admin import Admin
from models.admin_role import AdminRole
all = Admin.find().select('a.*').alias('a') \
    .join(table=AdminRole.tablename, alias='r', on='a.role=r.id') \
    .where('a.lock', '=', 0) \
    .all()
for one in all:
    print(one)

# case 4: join more than one table
from models.admin import Admin
from models.admin_role import AdminRole
from models.admin_auth import AdminAuth
all = Admin.find().select('username', 'a.role').alias('a') \
    .join(table=AdminRole.tablename, alias='r', on='a.role=r.id') \
    .join(table=AdminAuth.tablename, alias='t', on='t.role=r.id') \
    .where('t.action', '=', 300) \
    .all()
for one in all:
    print(one)

transaction

# case 1
from pymyorm.transaction import Transaction as t
from models.user import User
try:
    t.begin()
    model = User(name='ping', phone='18976641111', money=100)
    model.save()
    t.commit()
except Exception as e:
    t.rollback()
    raise e

# case 2 : nested transaction
from pymyorm.transaction import Transaction as t
try:
    t.begin()
    # ... your code
    try:
        t.begin()
        # ... your code
        t.commit()
    except Exception as e:
        t.rollback()
        raise e
    t.commit()
except Exception as e:
    t.rollback()
    raise e

connection pool

By default PyMyORM works at single thread, however when we develop a web application based on flask, we would like to make PyMyORM support multi-threading.

So PyMyORM provide a connection pool component, and it's threadsafety.

In this kind of scenario, we should use ConnectionPool to replace Database to init mysql connection.

import functools
from flask import Flask
from pymyorm.local import local
from pymyorm.connection_pool import ConnectionPool
from models.user import User

app = Flask(__name__)

config = dict(user=user, port=port, user=user, password=password, database=database)
pool = ConnectionPool()
pool.size(size=10)
pool.debug(debug=True)
pool.create(**config)


# assign one connection to the request
def assign_connection(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        pool = ConnectionPool()
        local.conn = pool.get()
        
        resp = func(*args, **kwargs)
        # don't forget to put connection into pool
        pool.put(local.conn)
        return resp
    return wrapper

@app.route('/')
@assign_connection
def index():
    one = User.find().where(name='ping').one()
    print(one)
    return 'index'

@app.route('/hello')
@assign_connection
def hello():
    one = User.find().where(name='ping').one()
    print(one)
    return 'hello'

As the code slice mentioned above, PyMyORM assign one mysql connection for each http request, so the mysql transaction will work properly.

Resource

• MySQL Reference Manuals: https://dev.mysql.com/doc/
• PyMySQL: https://pymysql.readthedocs.io/

License

PyMyORM is released under the MIT License. See LICENSE for more information.