Nova Calculated Field Laravel Package

Getting Started

composer require gldrenthe89/nova-calculated-field

There is nothing to publish and no migrations — this is a Nova field, not a service provider with config. It only does anything inside a resource's fields() method.

As of v2.4.1 the package no longer declares laravel/framework as a requirement, so it now installs cleanly alongside Laravel 10/11/12 as long as your laravel/nova version supports it. If you previously hit a Composer conflict pinning you to an older release, this is the release that unblocks you.

Where to look first:

1. The README for the field's constructor/calculateUsing-style callback signature.
2. vendor/gldrenthe89/nova-calculated-field/src/ — there is essentially one field class. Read it once and you know the whole package.

First use case: a display-only "Total" on a resource form, computed from other fields so you don't need a database column or a model observer.

use Gldrenthe89\NovaCalculatedField\CalculatedField; // confirm exact class in README

public function fields(NovaRequest $request): array
{
    return [
        Number::make('Price'),
        Number::make('Quantity'),

        CalculatedField::make('Total')
            ->calculateUsing(fn (array $values) => ($values['price'] ?? 0) * ($values['quantity'] ?? 0))
            ->exceptOnForms(), // if you only want it shown, not submitted
    ];
}

Implementation Patterns

Keep the formula in one place. The single biggest maintenance cost with calculated fields is the same formula drifting across fields(), fieldsForIndex(), lenses, and a resolveUsing somewhere. Put the formula in a static method or a small Calculator class, and have the Nova field call it:

// app/Nova/Support/InvoiceTotals.php
public static function total(array $values): float
{
    return round(($values['price'] ?? 0) * ($values['quantity'] ?? 0), 2);
}

Then both the Nova field and any unit test use InvoiceTotals::total(). The Nova field becomes wiring, which is the part you can't easily test anyway.

Index vs detail. Compute on the detail/form view where the user is actually editing inputs. On index pages, if the value is expensive (relationships, aggregates) you're better off persisting it — see below — or guarding with ->onlyOnDetail().

If you need sorting or filtering, persist. Calculated fields are display-time; they are not sortable or filterable over the database. If a user asks "sort by total", the answer is a real column updated in a model event/observer (or a DB generated column), not a tweaked calculated field. Trying to bolt ->sortable() onto a computed value is the classic dead end here.

Reuse through a factory method rather than copy-pasting the field definition — a MyFields::invoiceTotal() helper keeps the callback, formatting (->displayUsing(), currency helpers from Nova's own field API), and visibility flags consistent across resources.

Test the formula, not the field. Unit-test the calculator class. Only reach for Nova's HTTP/feature testing if you've genuinely got custom field logic.

Gotchas and Tips

• Upgrading to v2.4.1: run composer update gldrenthe89/nova-calculated-field --with-dependencies, then php artisan optimize:clear. No JS rebuild is needed on your side, but cached Nova assets occasionally mask a version change — a hard refresh fixes "it didn't update."
• What dropping laravel/framework actually means: the package now inherits the framework version pulled in by laravel/nova. Your app's composer.json must still require laravel/framework; don't infer from this release that you can drop it. And if you maintain a fork or run the package's own test suite in CI, check that require-dev still has the framework — a test bootstrap with no framework installed fails in confusing ways.
• Nulls on create forms. Callbacks often run before sibling fields are hydrated; $values['price'] can be missing entirely on first render. Always ?? 0 / null-guard, otherwise the create form throws before the user types anything.
• Missing keys, not just nulls. Fields hidden by canSee()/->hide() may not appear in $values at all, so $values['x'] raises an undefined-key warning rather than returning null. Same guard fixes both.
• Money and floats. PHP float math in the callback produces 19.999999999. Work in integer cents or use bcmath inside the formula, then format for display.
• "It doesn't recalculate." If the value only updates on save, the browser doesn't know the field depends on others. Check whether Nova's own dependent-field support (Nova 4+) is the right tool for this case — the two mechanisms don't compose, and mixing them is a common source of silent no-ops.
• N+1 on index. Any relationship access inside the callback fires per row. Eager-load in indexQuery() or keep computed fields off the index.
• Semver note: this is a patch bump, but it widens a dependency constraint rather than narrowing it, so there is no breakage risk for existing installs — no code changes, no config changes, no re-publish.