Relationships & N+1

Relations are the ORM feature that feels amazing until you accidentally fire 200 queries on a list page. Let's enjoy them carefully.

Common relation types

<?php

// User.php
public function posts(): HasMany
{
    return $this->hasMany(Post::class);
}

// Post.php
public function user(): BelongsTo
{
    return $this->belongsTo(User::class);
}

public function tags(): BelongsToMany
{
    return $this->belongsToMany(Tag::class);
}

Usage:

<?php

$user->posts;           // Collection of posts
$post->user->name;      // related user
$post->tags()->attach($tagId);

Eager loading (the important habit)

N+1 problem - list 50 posts, each touches $post->user → 1 + 50 queries.

<?php

// bad on index pages
$posts = Post::query()->latest()->get();
foreach ($posts as $post) {
    echo $post->user->name; // lazy query each time
}

// good
$posts = Post::query()->with('user')->latest()->get();

with('user.profile', 'tags') nests. withCount('posts') adds counts without loading rows.

Laravel Debugbar / DB::listen / Telescope - use something to see query counts while learning. Your FE brain knows "waterfalls"; this is the server equivalent.

Lazy vs eager (FE analogy)

Front-end	Eloquent
waterfall fetches in a list	lazy relations in a loop
React Query prefetch / GraphQL includes	with(...)
over-fetching	with too much data

Creating related models

<?php

$user->posts()->create([
    'title' => 'Hi',
    'body' => '…',
]);

Sets user_id for you. Cute and useful.

Soft deletes (quick peek)

<?php

use SoftDeletes;
// + $table->softDeletes() in migration

delete() sets deleted_at; queries hide those rows by default. Know it exists when data "vanishes" but the row is still in the DB.

Default rule for list pages: if you use a relation in the loop, eager load it.

Best,

-- ł.