Interactive explainers for Laravel and PHP

See how Laravel and PHP actually work, one mechanism at a time.

Each page takes one mechanism, a Laravel concept like an N+1 query or a queue retry, or core PHP like how preg_replace or a dynamic static call really works, and turns it into a simulator you can step through, break, and run again. You drive. Nothing plays at you.

Browse explainers Start with N+1 →
14 explainers, more on the way 12 topics light + dark, you choose

Queries & Eloquent

2 explainers

Where your queries come from, and when they fire.

Why eager loading changes the number of queries Watch the query counter climb to 51, then collapse to 2.
Why chunking can skip half your rows Eight rows, a loop that updates each one, and only five ever get visited. No error, no warning.

Models & data

1 explainer

How Eloquent turns rows into objects, and back.

How Eloquent casts raw database values into objects Watch a raw column string become an enum on read, then toggle a boolean twice and stay clean.

Database & transactions

1 explainer

Commit, rollback, locks, and the surprises between them.

What a nested transaction actually rolls back Nest transactions, commit and roll back, and see which writes actually survive.

Queues & jobs

1 explainer

What happens to a job after you dispatch it.

Why a failed job does not go straight to failed_jobs A failed job does not fail at once. Watch the attempts and the delay.

Caching

1 explainer

What the cache saves you, and how it fails under load.

The cache stampede, and what a lock prevents Fire a burst at a cold key, watch every request query the database, then add a lock and watch it collapse to one.

HTTP & container

1 explainer

How a request becomes a response, and who wires it up.

The middleware pipeline, and where the response comes back through Send a request down through the middleware to the controller, then watch the response come back out in reverse. Log the user out and watch it get turned away early.

Auth

1 explainer

Who the user is, and where that is stored.

Sanctum: a token or a cookie, depending on who is calling Send the same protected request as a first-party SPA and as a mobile app, and watch Sanctum authenticate one with a cookie and the other with a token.

Event sourcing

1 explainer

State as a log of events you can replay.

Why a projection is a view, not the source of truth Add a projector after the fact, replay, and watch it catch up.

Types & comparison

1 explainer

What == coerces before it compares, and why === does not.

Why == and === are not the same comparison Pick two values and watch == coerce them before it compares.

Strings & regex

2 explainers

How a pattern matches, backtracks, and sometimes blows up.

Catastrophic backtracking: when one regex melts a CPU Watch (a+)+$ try twice as many paths for every letter you add to a failing input, hit PHP's backtrack limit, then collapse to one path with an atomic group.
Why strlen and mb_strlen disagree about one string One string, three correct lengths. Drag the cut and watch substr stop halfway through a character.

References & memory

1 explainer

When a value is copied, when it is shared, and why.

When PHP copies a value, and when it shares it Assign, reference, and write, and watch a value share a box or split off its own.

Metaprogramming

1 explainer

How a call resolves when the method is not there.

Magic methods: how $user->name works when there is no name Resolve $user->name, $user->where() and $user->save() and watch which go through magic methods and which do not, then declare a real property and watch it shadow the column.