#connection-pooling code explainers

typescript

import { Injectable, Scope, Inject, NotFoundException } from '@nestjs/common';
import { REQUEST } from '@nestjs/core';
import { Request } from 'express';
import { DataSource } from 'typeorm';

Per-tenant database connections in NestJS

multi-tenancy connection-pooling dependency-injection

Advanced 8 steps

javascript

const { pool } = require('./db');
 
function withTransaction() {
  return async (req, res, next) => {

A per-request transaction middleware in Express

middleware database-transactions connection-pooling

Advanced 7 steps

java

public enum DataSourceType {
    PRIMARY,
    REPLICA
}

Read/write datasource routing in Spring

routing threadlocal read-replica

Intermediate 8 steps

python

from flask import Flask, g, current_app
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker

Scoped SQLAlchemy sessions in Flask

database session-management connection-pooling

Intermediate 6 steps

javascript

const { Pool } = require('pg');
 
const pool = new Pool({
  connectionString: process.env.DATABASE_URL,

Per-request Postgres connections in Express

connection-pooling middleware transactions

Intermediate 8 steps

rust

use axum::{
    extract::{FromRequestParts, Host},
    http::{request::Parts, StatusCode},
};

Multi-tenant DB routing in Axum extractors

multi-tenancy extractors connection-pooling

Advanced 8 steps

python

import requests
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry

Building a resilient requests Session

retries backoff http-client

Intermediate 7 steps