hainan/app/Admin/Forms/ServicePersonsSetting.php

<?php

namespace App\Admin\Forms;

use App\Traits\WithdrawalTraits;
use Dcat\Admin\Widgets\Form;

class ServicePersonsSetting extends Form
{
    /**
     * Handle the form request.
     *
     * @param array $input
     *
     * @return mixed
     */
    public function handle(array $input)
    {
		$system = \App\Models\SystemSetting::query()->firstOrCreate([
			'key' => 'single'
		]);

		$arr = [
			'price' => $input['price'],
		];
		$system->value = $arr;
		$system->save();
        return $this
				->response()
				->success('设置成功')
				->refresh();
    }

    /**
     * Build a form here.
     */
    public function form()
    {
		$this->decimal('price','单人头交易费')->rules('required|numeric|min:0|not_in:0',[
			'*' => '金额为必填字段且必须大于0',
		]);
    }

    /**
     * The data of the form.
     *
     * @return array
     */
    public function default()
    {
    	$system = \App\Models\SystemSetting::query()->where('key','single')->value('value');
        return [
			'price' => $system['price'] ?? 0,
        ];
    }
}