codesnips
javascript 
export const initialCart = { items: {} };

export function cartReducer(state, action) {
  switch (action.type) {
    case 'ADD_ITEM': {
      const { product, qty = 1 } = action;

Persist and Hydrate a Shopping Cart with useReducer and localStorage

react hooks usereducer
by codesnips 3 tabs
rust 
use std::any::Any;

pub trait CommandHandler {
    fn name(&self) -> &str;

    fn handle(&self, input: &dyn Any) -> Box<dyn Any>;

Type-Erased Command Handler Registry With Trait Objects in Rust

rust trait-objects dispatch
by codesnips 3 tabs
java 
package com.example.api.error;

import com.fasterxml.jackson.annotation.JsonInclude;

import java.time.Instant;
import java.util.List;

Structured Error Responses with @RestControllerAdvice in Spring Boot

spring-boot rest-api exception-handling
by codesnips 3 tabs
go 
package store

import (
	"context"
	"database/sql"
)

Propagating a Context Deadline for Per-Request Timeouts in Go HTTP Handlers

go context http
by codesnips 3 tabs
typescript 
import { useCallback, useEffect, useState } from "react";

type Patch = Record<string, string | null | undefined>;

function readParams(): URLSearchParams {
  return new URLSearchParams(window.location.search);

Sync a Filter Panel to the URL Query String with a Custom useSearchParams Hook

react hooks url-state
by codesnips 3 tabs
ruby 
class AddVersionsToArticles < ActiveRecord::Migration[7.1]
  def change
    add_column :articles, :versions, :jsonb, null: false, default: []
    add_index :articles, :versions, using: :gin
  end
end

Versioning Rails Records with a JSON Snapshot Column and Diff Helper

rails postgres jsonb
by codesnips 3 tabs
python 
from typing import Any, Optional

from fastapi.responses import JSONResponse
from pydantic import BaseModel

Consistent JSON Error Responses in FastAPI With a Custom Exception Handler

fastapi error-handling exceptions
by codesnips 3 tabs
javascript 
import { useState, useRef, useEffect, useCallback } from "react";

export function useCarousel(length, { delay = 4000 } = {}) {
  const [index, setIndex] = useState(0);
  const [paused, setPaused] = useState(false);
  const savedCallback = useRef(null);

Autoplay Image Carousel in React with Pause-on-Hover via useRef and useEffect

react hooks carousel
by codesnips 3 tabs
rust 
use std::sync::mpsc::{self, SyncSender};
use std::sync::{Arc, Mutex};
use std::thread;

mod worker;
use worker::{Message, Worker};

Bounded Thread Pool With Backpressure Using Rust Channels

threads concurrency channels
by codesnips 3 tabs
rust 
#[derive(Debug, Clone)]
pub enum Outcome {
    Approve,
    Review,
    Reject(String),
}

Modeling and Evaluating a Decision Tree with Recursive Rust Enums

rust enums recursion
by codesnips 3 tabs
java 
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.JsonTypeInfo.As;
import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;

import java.math.BigDecimal;

Deserialize Polymorphic JSON into a Sealed Interface Hierarchy with Jackson

jackson json deserialization
by codesnips 3 tabs
ruby 
class RevenueStat
  DEFAULT_RANGE = 30.days

  def initialize(account, range: DEFAULT_RANGE)
    @account = account
    @range = range

Memoized Query Object for a Cached Dashboard Stat in Rails

rails activerecord query-object
by codesnips 3 tabs