How to share db pool/session data between multiple requests?

edoardoc · October 13, 2019, 6:42pm

Hello,
up to today I’ve used BottlePy + psycopg2 for my website, but I’d like to move from that to Sanic + asyncpg.

Is there something equivalent to Vibora components (https://docs.vibora.io/initial#components), or bottlepy plugins (https://bottlepy.org/docs/dev/tutorial.html#plugins)?

I could just use middlewares, and add db and session to the request (a simple request.db = pgpool) but since session has a bit of overhead (have to execute some queries) i would like to only pass it to the routes that need it.

shady-robot · October 15, 2019, 6:13am

@edoardoc Why not add it to the app instead? By utilize the before_server_start, you can add the connection pool to the app.

@app.listener("before_server_start")
async def before_server_start(app, loop):
    config = app.config["DB_CONFIG"]
    # Config for Mysql Connection
    config["db"] = config["database"]
    app.db = await ConnectionPool(loop=loop, trace=True).init(app.config["DB_CONFIG"])

If I understand your question right, you can refer this demo project that I’m currently working.
sanic_seckill

github.com

itechub/seckill-sanic/blob/docs/readme-multi-language/config/server.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import asyncio
import datetime
import yaml
import os
import opentracing
from collections import defaultdict

from sanic import Sanic, config
from sanic.response import json, text, HTTPResponse
from sanic.exceptions import RequestTimeout, NotFound
from sanic_openapi import swagger_blueprint


from config import load_config
from config.db import ConnectionPool
from config.utils import CustomHandler
from config.exceptions import NotFound

This file has been truncated. show original

edoardoc · October 15, 2019, 4:34pm

I cannot add to app because I’m using blueprints, and blueprints don’t have access to the app.

mike · October 16, 2019, 3:44pm

check request.app to get access to the app.db

shady-robot · October 16, 2019, 4:46pm

even you use Blueprint I think you still can access the app within request.

github.com

itechub/seckill-sanic/blob/0e661266f970fa3b4db063bebdecb2d74c3f8988/activity/views.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2019 shady <[email protected]>
#

import logging
import datetime
import time
import asyncio

from sanic import Blueprint
from sanic.response import json
from config.server import tracing
from models import *

seckill_bp = Blueprint("activity", url_prefix="activities")

This file has been truncated. show original

edoardoc · October 16, 2019, 4:40pm

Thanks guys, i didn’t know about that.
How about the function in bottlepy where handlers get passed objects depending if they have specific keywords in their arguments? This could be, again, handy for routes that need components that sometimes have some overhead to get.

For example, log_out_user(request, session) would have session passed to it automatically.