Add ability to use Closure as a sortable parameter in table's column

[Jampire]

Hi
This PR makes possible to use self-defined Closure as sortable parameter for table's column.

There can be a case when you need to sort by computed or virtual column. You can't just set sortable: true in call to column() method. You can use Spatie Query Builder for such case. But this solution for those who don't want to install it just for one field.

So, let's say you have such Eloquent model:

<?php

class Subscriber extends Model
{
    protected $appends = [
        'full_name',
    ];

    protected $fillable = [
        'first_name',
        'last_name',
    ];

    public function fullName(): Attribute
    {
        return Attribute::make(
            get: fn () => trim(sprintf('%s %s', $this->first_name, $this->last_name)),
        );
    }
}

And you want to sort by full_name. Then you can do:

<?php

class SubscribersViewTable extends AbstractTable
{
    /**
     * Determine if the user is authorized to perform bulk actions and exports.
     *
     * @param Request $request
     * @return bool
     */
    public function authorize(Request $request): bool
    {
        return true;
    }

    /**
     * The resource or query builder.
     *
     */
    public function for(): Builder
    {
        return Subscriber::query();
    }

    /**
     * Configure the given SpladeTable.
     *
     * @param SpladeTable $table
     * @return void
     */
    public function configure(SpladeTable $table): void
    {
        $table
            ->withGlobalSearch(columns: [
                'first_name',
                'last_name',
            ])
            ->column(
                key: 'full_name',
                sortable: fn (Builder $query, string $direction) => $query
                    ->orderBy('first_name', $direction)
                    ->orderBy('last_name', $direction),
            )
            ->searchInput(
                key: ['first_name', 'last_name'],
                label: 'Full Name',
            )
            ->paginate(10)
        ;
    }
}

P.S. I don't find instructions on how to set-up tests. So, right now there are no tests of this functionality.

[pascalbaljet]

Very cool! Thank you :)