Lazy Evaluation Not Working as Expected

[joue-zero]

Hi, I’m trying to use lazy data evaluation in Inertia.js as per the documentation. However, when I wrap a prop in a closure (e.g., users), it gets evaluated even if the prop is not used on the page.

Example Code:

return Inertia::render('TestPage', [
    'users' => fn () => {
        sleep(10); // Simulate delay
        return User::all();
    },
    'companies' => fn () => Company::all(),
]);

If I visit TestPage that doesn’t use the users prop or not even accept users

as prop, it still takes 10 seconds to load, meaning the closure is being evaluated.

Expected Behavior:
The users closure should not be evaluated if the prop is not used on the page.

Questions:

• Why is the closure being evaluated even when the prop is not used?

• Am I missing something in the setup?

[hakimzulkufli]

That is expected. As per the documentation that you linked, wrapping the value in a Closure will only make it lazy-loaded on subsequent requests via Inertia when requested. First visit will always be evaluated and included with this method.

Whether you accept it as a prop or not does not matter as the props definition in the page only tells the page what props are available to be used. It does not mean the page will request only those props when loading the page.

In order to make sure that it's only evaluated when requested (meaning: completely lazy-loaded via a separate request), you need to wrap it in Inertia::lazy().

For reference, see the examples below: (Copy-pasted the documentation page)

return Inertia::render('Users/Index', [
    // ALWAYS included on standard visits
    // OPTIONALLY included on partial reloads
    // ALWAYS evaluated
    'users' => User::all(),

    // ALWAYS included on standard visits
    // OPTIONALLY included on partial reloads
    // ONLY evaluated when needed
    'users' => fn () => User::all(),

    // NEVER included on standard visits
    // OPTIONALLY included on partial reloads
    // ONLY evaluated when needed
    'users' => Inertia::lazy(fn () => User::all()),

    // ALWAYS included on standard visits
    // ALWAYS included on partial reloads
    // ALWAYS evaluated
    'users' => Inertia::always(User::all()),
]);

[joue-zero]

thank u, got it