ruby 39 lines · 7 steps

Building a JSON:API endpoint in Rails

A versioned API controller that paginates, eager-loads, and serializes articles while avoiding N+1 queries.

Explained by highlit
Rails Intermediate serialization eager-loading pagination n+1-queries rest-api
1class Api::V1::ArticlesController < Api::V1::BaseController
2 def index
3 articles = Article
4 .published
5 .includes(:author, :categories, comments: :author, cover_image_attachment: :blob)
6 .order(published_at: :desc)
7 .page(params[:page])
8 .per(25)
9 
10 render json: ArticleSerializer.new(
11 articles,
12 include: %i[author categories comments comments.author],
13 meta: pagination_meta(articles)
14 ).serializable_hash
15 end
16 
17 def show
18 article = Article
19 .includes(:author, :categories, { comments: %i[author reactions] })
20 .find(params[:id])
21 
22 render json: ArticleSerializer.new(
23 article,
24 include: %i[author categories comments comments.author comments.reactions]
25 ).serializable_hash
26 end
27 
28 private
29 
30 def pagination_meta(scope)
31 {
32 current_page: scope.current_page,
33 next_page: scope.next_page,
34 prev_page: scope.prev_page,
35 total_pages: scope.total_pages,
36 total_count: scope.total_count
37 }
38 end
39end
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Chaining includes with nested hashes preloads deep associations in one pass, sidestepping N+1 queries.
  2. 2Pagination metadata belongs in a reusable helper so multiple actions return a consistent response shape.
  3. 3A serializer's include option controls exactly which related records appear, keeping payloads intentional.

Related explainers

ruby 
require "shellwords"
require "open3"
 
module Backup

Building safe shell commands in Ruby

shell-out subprocess command-injection
Intermediate 7 steps
ruby 
class UserAgentParser
  BROWSERS = [
    [/Edg\/([\d.]+)/, "Edge"],
    [/OPR\/([\d.]+)/, "Opera"],

Parsing user-agent strings in Ruby

regex pattern-matching lookup-tables
Intermediate 8 steps
rust 
use axum::{
    extract::{Path, State},
    response::sse::{Event, KeepAlive, Sse},
};

Streaming import progress with SSE in Axum

server-sent-events streams watch-channel
Advanced 7 steps
ruby 
class LogAggregator
  BUCKET_FORMAT = "%Y-%m-%dT%H:%M"
 
  def initialize(entries)

Bucketing log entries by the minute in Ruby

aggregation hashing enumerable
Intermediate 5 steps
ruby 
class WeeklySignupsReport
  DEFAULT_WEEKS = 12
 
  def initialize(weeks: DEFAULT_WEEKS, source: User.all)

Building a weekly signups report in Rails

service object aggregation group by
Intermediate 7 steps
php 
<?php
 
namespace App\Services;
 

Building a cached daily leaderboard in Laravel

caching aggregation eager-loading
Intermediate 9 steps

Share this explainer

Here's the card — post it anywhere.

Building a JSON:API endpoint in Rails — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code