Partial Reloads

A visit to the page the client is on can ask for some of its props only:

router.reload({ only: ['users'] })
router.reload({ except: ['companies'] })

The client sends the component in X-Inertia-Partial-Component and the paths in X-Inertia-Partial-Data or X-Inertia-Partial-Except. When the component matches the page being rendered, render() resolves only the selected props:

• only keeps the listed paths; except removes them; with both, only narrows first and except removes from what is left.
• A path selects a branch: auth is all of auth, auth.user only that key inside it.
• errors and always props are sent whatever the paths say.
• A value resolved as a whole, such as a Closure that returns an array, is sent whole.

When the visit ends on another component — the user was signed out and redirected to the login page — the response is a full one.

Lazy props

A prop wrapped in a Closure is called only when the response sends it, so a partial reload costs only what it asks for:

return $this->inertia->render($request, $response, 'Users/Index', [
    'users' => fn() => $this->users->filtered($filters),
    'companies' => fn() => $this->companies->all(),
]);

Prop	Full visit	Partial reload	Resolved
$this->users->all()	sent	when selected	always
fn() => $this->users->all()	sent	when selected	when sent
Inertia::optional(fn() => ...)	never	when selected	when sent
Inertia::always(fn() => ...)	sent	sent	always
Inertia::defer(fn() => ...)	announced	when selected	when sent

Optional props

An optional prop is never part of a full visit, and the client is not told about it: it is sent only when a partial reload selects it.

'roles' => Inertia::optional(fn() => $this->roles->all()),

A reload with except only selects every prop it does not exclude, optional ones included.

Always props

An always prop is sent on every response, even a partial reload that did not ask for it:

'flags' => Inertia::always(fn() => $this->features->enabled()),

The errors prop is one. An always prop cannot be a once prop.

Resetting props

router.reload({ reset: ['results'] }) sends X-Inertia-Reset: results. The prop is resolved again and sent without its merge label, so the client replaces it; an infinite scroll prop gets reset: true in its metadata.