Nova Multiselect Field Laravel Package

Getting Started

Install the package with Composer (note that the Composer name and PHP namespace differ — see Gotchas):

composer require optimistdigital/nova-multiselect-field

Nova 4/5 auto-registers the field's assets through the package's service provider; no vendor:publish or manual Nova::script() call is normally needed. Just make sure you're on the major that matches your Nova version (^4.x for Nova 4, older tags for Nova 3).

First use case — a tags column on a Post model:

use Outl1ne\MultiselectField\Multiselect;

public function fields(NovaRequest $request)
{
    return [
        Multiselect::make('Tags', 'tags')
            ->options([
                'laravel'  => 'Laravel',
                'vue'      => 'Vue',
                'nova'     => 'Nova',
            ])
            ->saveAsJSON()
            ->searchable()
            ->rules('array'),
    ];
}

Add the cast on the model when using saveAsJSON():

protected $casts = ['tags' => 'array'];

Two things to decide immediately, because they're hard to change later: storage format (comma-separated string is the default; saveAsJSON() is almost always what you want) and whether the column is text/json. If in doubt, use JSON — it survives values containing commas, and it round-trips cleanly against the array cast.

Implementation Patterns

Static options. The simplest form is a key => label array. Keys become the stored values, labels are what the user sees. Stick to scalars — strings and ints are safe; objects and arrays are not.

Dynamic / dependent options. options() accepts a closure, which is evaluated server-side each time the field resolves:

Multiselect::make('Subcategories')
    ->options(fn () => Category::where('parent_id', $this->parent_id)->pluck('name', 'id'))
    ->saveAsJSON()
    ->dependsOn('parent_id'), // Nova reloads the field when parent_id changes

This is the idiomatic pattern for cascading selects. Keep the closure cheap — it runs on every resolve, including index rows if the field is visible there.

Large lists. Add ->searchable() (backed by vue-multiselect) and ->max(n) to cap selections. ->placeholder('Pick tags…') is worth setting for discoverability, especially on empty nullable fields.

Validation. The request payload arrives as an array, so pair it with ->rules('array') and validate the values, not the labels:

->rules('array')
->rules(fn () => ['array', Rule::in(array_keys($this->allOptions))])

->nullable() plus array rules avoids "must be an array" errors on optional fields.

Display. On index/detail views the raw stored value is shown unless you customize it. Use Nova's displayUsing() to map keys to labels for a readable index column, and hideFromIndex() if the column is noisy. Because the stored value is often IDs, a naive index shows 3,17,42 — worth fixing early.

Multiple fields, one resource. Fields are independent; there is no shared state. If you need pivot-backed many-to-many, use Nova's BelongsToMany/MorphToMany instead — this field is for a single denormalized column, not relations.

Gotchas and Tips

• Vendor/namespace mismatch. Composer package is optimistdigital/nova-multiselect-field, the PHP namespace is Outl1ne\MultiselectField, and the GitHub org is outl1ne. Don't "correct" the import to OptimistDigital\... — it will fail.
• Default storage is a comma-separated string. Any value containing the separator corrupts the data silently. Use saveAsJSON() unless you have a strong reason not to. If you must use strings, saveAsString() accepts an alternate separator in recent versions — verify the signature for your pinned release.
• Don't double-encode. With saveAsJSON() + the array cast, the package handles encoding. If you also json_encode in a mutator or accessor, you'll get "[\"a\",\"b\"]" stored as a string and a broken field on edit. Pick one layer.
• Options callable shape. Return pluck('label', 'id') or an associative array. Returning a list of Eloquent models produces labels like {"id":1,...} and a confusing UI.
• Eager-load / cache options. A closure hitting the DB for every index row is a classic N+1. Prefer ->onlyOnForms() or hideFromIndex(), or memoize the query result.
• Empty submissions. A cleared field can post [], null, or be absent depending on Nova version. If you see stale values on save, confirm your fillAttributeFromRequest path is receiving the key — log $request->all() in a temporary resolve/fill override.
• Debugging field meta. dd($field->json, $field->options) in a throwaway route, or inspect the fields payload in the Nova resource response in the browser network tab. Most "options not showing" issues are shape or visibility problems, not JS.
• Version pinning. Because the package is renamed and actively tagged, pin a major in composer.json and check the changelog when bumping Nova — the asset build (Nova 3 webpack vs Nova 4 Vite) changed across majors and a mismatch results in a field that renders as an empty div.
• Extending. Custom behavior usually belongs in resolveUsing() / displayUsing() or a subclass overriding options(), rather than patching vendor files. The package ships no views worth publishing for typical use.