Code Explainers

Code explainers tagged #validation

typescript 
import { NestFactory } from '@nestjs/core';
import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
import { ValidationPipe } from '@nestjs/common';
import { ApiProperty } from '@nestjs/swagger';

Wiring validation and Swagger docs in NestJS

validation openapi decorators
Intermediate 8 steps
typescript 
import { parsePhoneNumberFromString, CountryCode } from 'libphonenumber-js';
 
export interface NormalizedPhone {
  e164: string;

Normalizing phone numbers to E.164 in TypeScript

validation normalization error-handling
Intermediate 7 steps
php 
<?php
 
namespace App\Http\Controllers;
 

Broadcasting typing indicators in Laravel

websockets authorization presence-channels
Intermediate 9 steps
python 
def is_valid_card_number(number: str) -> bool:
    digits = [int(c) for c in number if c.isdigit()]
 
    if len(digits) < 13 or len(digits) > 19:

Validating card numbers with the Luhn check

checksum validation luhn-algorithm
Intermediate 6 steps
go 
func (h *ArticleHandler) Create(c *gin.Context) {
	var req struct {
		Title   string `json:"title" binding:"required"`
		Body    string `json:"body" binding:"required"`

Handling a POST request in Gin

request binding validation http status codes
Intermediate 7 steps
ruby 
require "base64"
require "json"
 
module Attachment

Packing binary attachments into JSON

serialization base64 json
Intermediate 8 steps
javascript 
function isValidCardNumber(input) {
  const digits = String(input).replace(/[\s-]/g, '');
 
  if (!/^\d{13,19}$/.test(digits)) {

Validating card numbers with Luhn

checksum validation luhn-algorithm
Intermediate 7 steps
python 
from werkzeug.routing import BaseConverter, ValidationError
from flask import Flask, jsonify, abort
 
 

Custom URL converters in Flask

url-routing validation converters
Intermediate 6 steps
typescript 
type RGB = { r: number; g: number; b: number };
 
type WCAGLevel = "AA" | "AAA";
type TextSize = "normal" | "large";

Checking WCAG color contrast in TypeScript

accessibility color-math type-safety
Intermediate 10 steps
javascript 
function hexToRgb(hex) {
  const normalized = hex.replace(/^#/, '');
  const full = normalized.length === 3
    ? normalized.split('').map((c) => c + c).join('')

Building a two-way color picker in JS

bitwise dom-events data-conversion
Intermediate 9 steps
ruby 
class Contact < ApplicationRecord
  PHONE_FORMATS = {
    "US" => /\A\+1\d{10}\z/,
    "GB" => /\A\+44\d{10}\z/,

Country-aware phone validation in Rails

validation callbacks regex
Intermediate 6 steps
go 
package handler
 
import (
	"net/http"

Custom time validation in Gin

validation request-binding struct-tags
Intermediate 8 steps
go 
package middleware
 
import (
	"net/http"

Localized validation errors in Gin

middleware internationalization validation
Intermediate 8 steps
java 
package com.example.validation;
 
import java.util.List;
import java.util.stream.Collectors;

Validating JSON payloads against a schema in Java

json-schema validation recursion
Intermediate 8 steps
python 
from flask import Blueprint, jsonify
from marshmallow import Schema, fields, validate, EXCLUDE
from webargs.flaskparser import use_args
 

Validating query params in Flask with webargs

validation schema query-building
Intermediate 10 steps
go 
package email
 
import (
	"errors"

Normalizing and deduping email addresses in Go

validation normalization deduplication
Intermediate 8 steps
javascript 
const express = require('express');
const multer = require('multer');
const path = require('path');
const crypto = require('crypto');

Safe image uploads with Multer in Express

file-upload multer validation
Intermediate 7 steps
php 
<?php
 
namespace App\Http\Requests;
 

A validated date-range value object in PHP

value-object validation immutability
Intermediate 7 steps