Laravel Nova自定义字段获取模型值

<?php

namespace App\Nova\Fields;

use Laravel\Nova\Fields\Field;

class CustomField extends Field
{
    /**
     * The field's component.
     *
     * @var string
     */
    public $component = 'custom-field';

    /**
     * Fill the given attribute on the model based on the incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  string  $requestAttribute
     * @param  object  $model
     * @param  string  $attribute
     * @return void
     */
    protected function fillAttributeFromRequest($request, $requestAttribute, $model, $attribute)
    {
        $model->{$attribute} = $request->{$requestAttribute};
    }
}

use App\Nova\Fields\CustomField;
use Laravel\Nova\Nova;

public function boot()
{
    Nova::addFields([
        CustomField::make('Custom Field', 'custom_field'),
    ]);
}