aiopg

aiopg is a library for accessing a PostgreSQL database from the asyncio (PEP-3156/tulip) framework. It wraps asynchronous features of the Psycopg database driver.

Features

Basics

The library uses psycopg2 connections in asynchronous mode internally.

Literally it is an (almost) transparent wrapper for psycopg2 connection and cursor, but with only exception.

You should use yield from conn.f() instead of just call conn.f() for every method.

Properties are unchanged, so conn.prop is correct as well as conn.prop = val.

See example:

import asyncio
import aiopg

dsn = 'dbname=aiopg user=aiopg password=passwd host=127.0.0.1'

async def go():
    async with aiopg.create_pool(dsn) as pool:
        async with pool.acquire() as conn:
            async with conn.cursor() as cur:
                await cur.execute("SELECT 1")
                ret = []
                async for row in cur:
                    ret.append(row)
                assert ret == [(1,)]

loop = asyncio.get_event_loop()
loop.run_until_complete(go())

For documentation about connection and cursor methods/properties please go to psycopg docs: http://initd.org/psycopg/docs/

Note

psycopg2 creates new connections with autocommit=True option in asynchronous mode. Autocommitting cannot be disabled.

See Transactions about transaction usage in autocommit mode.

Note

Throughout this documentation, examples utilize the async/await syntax introduced by PEP 492 that is only valid for Python 3.5+.

If you are using Python 3.4, please replace await with yield from and async def with a @coroutine decorator. For example, this:

async def coro(...):
    ret = await f()

shoud be replaced by:

@asyncio.coroutine
def coro(...):
    ret = yield from f()

see also yield from/@coroutine style examples.

SQLAlchemy and aiopg

Core API Reference provides core support for PostgreSQL connections.

We have found it to be very annoying to write raw SQL queries manually, so we introduce support for sqlalchemy query builders:

import asyncio
from aiopg.sa import create_engine
import sqlalchemy as sa


metadata = sa.MetaData()

tbl = sa.Table('tbl', metadata,
               sa.Column('id', sa.Integer, primary_key=True),
               sa.Column('val', sa.String(255)))

async def go():
    async with create_engine(user='aiopg',
                             database='aiopg',
                             host='127.0.0.1',
                             password='passwd') as engine:
        async with engine.acquire() as conn:
            await conn.execute(tbl.insert().values(val='abc'))

            async for row in conn.execute(tbl.select().where(tbl.c.val=='abc'))
                print(row.id, row.val)


loop = asyncio.get_event_loop()
loop.run_until_complete(go())

We believe constructions like tbl.insert().values(val='abc') and tbl.select().where(tbl.c.val=='abc') to be very handy and convenient.

Installation

pip3 install aiopg

Note

aiopg requires psycopg2 library.

You can use standard one from your distro like:

$ sudo apt-get install python3-psycopg2

but if you like to use virtual environments (virtualenvwrapper, virtualenv or venv) you probably have to install libpq development package:

$ sudo apt-get install libpq-dev

Also you probably want to use aiopg.sa.

aiopg.sa module is optional and requires sqlalchemy. You can install sqlalchemy by running:

pip3 install sqlalchemy

Source code

The project is hosted on GitHub

Please feel free to file an issue on bug tracker if you have found a bug or have some suggestion for library improvement.

The library uses Travis for Continious Integration.

Discussion list

aio-libs google group: https://groups.google.com/forum/#!forum/aio-libs

Feel free to post your questions and ideas here.

Dependencies

Indices and tables