Code Explainers

Code explainers tagged #error-handling

typescript 
import { Injectable, NotFoundException, ConflictException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, DeepPartial } from 'typeorm';
import { User } from './entities/user.entity';

Building a CRUD service in NestJS

crud dependency-injection repository-pattern
Intermediate 7 steps
php 
<?php
 
namespace App\Queue;
 

A stable priority job queue in PHP

priority-queue data-structures closures
Intermediate 8 steps
typescript 
import { Controller, Get, Param, Query, Redirect, NotFoundException } from '@nestjs/common';
import { LinksService } from './links.service';
 
@Controller('links')

Handling HTTP redirects in NestJS

redirects routing decorators
Intermediate 7 steps
ruby 
require "net/http"
require "json"
 
class UrlFetcher

A thread-pool URL fetcher in Ruby

concurrency thread-pool queues
Intermediate 8 steps
go 
package auth
 
import (
	"errors"

Hashing and verifying passwords with bcrypt in Go

password-hashing bcrypt error-handling
Intermediate 7 steps
typescript 
import { useState, useCallback } from 'react';
 
type Todo = {
  id: string;

Optimistic UI updates in a React hook

optimistic-updates custom-hooks error-handling
Intermediate 8 steps
rust 
use std::fs::File;
use std::io::{self, Read};
use std::path::Path;
 

Streaming a SHA-256 hash of a file in Rust

hashing buffered-io streaming
Intermediate 5 steps
go 
package fsutil
 
import (
	"io/fs"

Walking a directory tree to find large files in Go

filesystem recursion closures
Intermediate 7 steps
ruby 
class DatasetImportJob < ApplicationJob
  queue_as :default
 
  def perform(import)

Streaming import progress with a Rails job

background-jobs turbo-streams progress-tracking
Intermediate 9 steps
rust 
use bytes::{Buf, BufMut, BytesMut};
use tokio_util::codec::{Decoder, Encoder};
 
const MAX_FRAME: usize = 8 * 1024 * 1024;

A length-prefixed frame codec in Tokio

framing codecs buffers
Intermediate 8 steps
rust 
use axum::{
    body::{Body, Bytes},
    extract::Request,
    http::StatusCode,

Logging request bodies in Axum middleware

middleware streaming-body logging
Intermediate 8 steps
rust 
use std::time::Duration;
 
use axum::{
    body::Body,

Turning Axum timeouts into 504 JSON

middleware timeouts error-handling
Intermediate 7 steps
go 
package tsvio
 
import (
	"bufio"

Reading and writing TSV records in Go

parsing io-streams error-handling
Intermediate 10 steps
typescript 
type QueuedRequest = {
  id: string;
  url: string;
  method: string;

A retry queue with exponential backoff

retry exponential-backoff persistence
Intermediate 10 steps
ruby 
class Order
  class InvalidTransition < StandardError; end
 
  TRANSITIONS = {

A state machine for order transitions in Ruby

state-machine data-driven error-handling
Intermediate 8 steps
rust 
use std::cmp::Ordering;
use std::str::FromStr;
 
#[derive(Debug, Clone, PartialEq, Eq)]

Parsing and ordering semantic versions in Rust

parsing trait-implementation ordering
Intermediate 8 steps
javascript 
'use client';
 
import { useEffect } from 'react';
import * as Sentry from '@sentry/nextjs';

How a Next.js error boundary recovers

error-boundary error-handling observability
Intermediate 8 steps
ruby 
class Registration < ApplicationRecord
  belongs_to :event
 
  validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }

Validating registrations in Rails

validations i18n error-handling
Intermediate 8 steps