Add ->filterable() support

[ziming]

It would be really cool if spatie nova tags field support the ->filterable() method in Nova 4

https://nova.laravel.com/docs/4.0/releases.html#filterable-fields

[fritz-c]

Following the instructions here
https://nova.laravel.com/docs/v5/filters/registering-filters
You can register this custom one, which more or less will do what you're aiming for there:

<?php

namespace App\Nova\Filters;

use Illuminate\Contracts\Database\Eloquent\Builder;
use Laravel\Nova\Filters\BooleanFilter;
use Laravel\Nova\Http\Requests\NovaRequest;
use Spatie\Tags\Tag;

class Tags extends BooleanFilter
{
    /**
     * Create a new filter instance.
     */
    public function __construct(
        protected ?string $tagType = null
    ) {}

    /**
     * Apply the filter to the given query.
     */
    public function apply(NovaRequest $request, Builder $query, mixed $value): Builder
    {
        $selectedTagIds = collect($value)->filter()->keys();

        return $query
            ->when(
                $selectedTagIds->isNotEmpty(),
                fn ($q) => $q->whereHas(
                    'tags',
                    fn ($q) => $q->where('type', $this->tagType)->whereIn('id', $selectedTagIds)
                )
            );
    }

    /**
     * Get the filter's available options.
     *
     * @return array<string, string>
     */
    public function options(NovaRequest $request): array
    {
        return Tag::where('type', $this->tagType)->get()->pluck('id', 'name')->toArray();
    }
}

If you're using tag types, for example my-tag-type, you can specify which type for the filter to use with:

/**
 * Get the filters available for the resource.
 *
 * @return array
 */
public function filters(NovaRequest $request)
{
    return [
        new Filters\Tags('my-tag-type'),
    ];
}