einundzwanzig-portal/app/Nova/Lecturer.php

<?php

namespace App\Nova;

use Ebess\AdvancedNovaMediaLibrary\Fields\Images;
use Illuminate\Http\Request;
use Laravel\Nova\Fields\BelongsTo;
use Laravel\Nova\Fields\Boolean;
use Laravel\Nova\Fields\Field;
use Laravel\Nova\Fields\Text;
use Laravel\Nova\Http\Requests\NovaRequest;

class Lecturer extends Resource
{
    /**
     * The model the resource corresponds to.
     * @var string
     */
    public static $model = \App\Models\Lecturer::class;

    /**
     * The single value that should be used to represent the resource when being displayed.
     * @var string
     */
    public static $title = 'name';

    /**
     * The columns that should be searched.
     * @var array
     */
    public static $search = [
        'id',
        'name',
    ];

    public static function relatableTeams(NovaRequest $request, $query, Field $field)
    {
        if ($field instanceof BelongsTo) {
            $query->where('id', $request->user()->current_team_id);
        }

        return $query;
    }

    /**
     * Get the fields displayed by the resource.
     *
     * @param  \Illuminate\Http\Request  $request
     *
     * @return array
     */
    public function fields(Request $request)
    {
        return [
            Images::make('Avatar', 'avatar') // second parameter is the media collection name
                  ->conversionOnIndexView('thumb') // conversion used to display the image
                  ->rules('required'), // validation rules

            Text::make('Name')
                ->rules('required', 'string'),

            Text::make('Slug')
                ->rules('required', 'string', 'unique:lecturers,slug')
                ->exceptOnForms(),

            Boolean::make('Active')
                   ->rules('required')
                   ->default(true),

            BelongsTo::make('Team'),

        ];
    }

    /**
     * Get the cards available for the request.
     *
     * @param  \Illuminate\Http\Request  $request
     *
     * @return array
     */
    public function cards(Request $request)
    {
        return [];
    }

    /**
     * Get the filters available for the resource.
     *
     * @param  \Illuminate\Http\Request  $request
     *
     * @return array
     */
    public function filters(Request $request)
    {
        return [];
    }

    /**
     * Get the lenses available for the resource.
     *
     * @param  \Illuminate\Http\Request  $request
     *
     * @return array
     */
    public function lenses(Request $request)
    {
        return [];
    }

    /**
     * Get the actions available for the resource.
     *
     * @param  \Illuminate\Http\Request  $request
     *
     * @return array
     */
    public function actions(Request $request)
    {
        return [];
    }
}