laravel

Eloquent N+1

• Accessing relationship in loop without eager load — User::with('posts')->get() not User::all() then ->posts
• Nested relationships need dot notation — with('posts.comments') for eager loading
• withCount('posts') for counting without loading — adds posts_count attribute
• preventLazyLoading() in AppServiceProvider — crashes on N+1 in dev, catches bugs early

Mass Assignment

• $fillable whitelist OR $guarded blacklist — not both
• $guarded = [] allows all fields — dangerous, prefer explicit $fillable
• create() and update() respect mass assignment — $model->field = x bypasses it
• Request validated data is not auto-safe — still filtered by fillable/guarded

Cache Pitfalls

• config:cache bakes .env values — env() only works in config files after caching
• route:cache requires all routes to be controller-based — no closures
• php artisan optimize combines config, route, view cache — run after deploy
• Local changes not reflecting — php artisan cache:clear && config:clear && route:clear

Queue Jobs

• Job class properties serialized — models serialize as ID, re-fetched on process
• Closure can't be queued — must be invocable class
• Failed jobs go to failed_jobs table — check there for errors
• $tries, $timeout, $backoff as job properties — or in config
• Connection vs queue: connection is driver, queue is named channel on that driver

Middleware

• Order matters — earlier middleware wraps later
• $middleware global on every request — $middlewareGroups for web/api
• Terminate middleware runs after response sent — for logging, cleanup
• Route middleware can have parameters — role:admin passes 'admin' to middleware

Database

• migrate:fresh drops ALL tables — migrate:refresh rolls back then migrates
• DB::transaction() auto-rolls back on exception — but not on manual exit or timeout
• Soft deletes excluded by default — withTrashed() to include
• firstOrCreate vs firstOrNew — first persists, second doesn't

Testing

• RefreshDatabase is faster than DatabaseMigrations — uses transactions
• Factories: create() persists, make() doesn't — use make for unit tests
• $this->withoutExceptionHandling() shows actual errors — helpful for debugging
• Queue fake: Queue::assertPushed() — check job was queued without running it

Common Mistakes

• find() returns null, findOrFail() throws 404 — use OrFail to avoid null checks
• env() in cached config returns null — only use env() inside config files
• Validation required doesn't mean non-empty — use required|filled for strings
• Route model binding uses id by default — getRouteKeyName() to change