lianjie_admin/app/Admin/Controllers/CategoryController.php

<?php

namespace App\Admin\Controllers;

use App\Models\Category;
use Dcat\Admin\Form;
use Dcat\Admin\Layout\Row;
use Dcat\Admin\Layout\Content;
use Dcat\Admin\Tree;
use Dcat\Admin\Controllers\AdminController;

class CategoryController extends AdminController
{
    public function index(Content $content)
    {
        return $content->header('树状模型')
            ->body(function (Row $row) {
                $tree = new Tree(new Category);

                $row->column(12, $tree);
            });
    }

    public function form()
    {
        return Form::make(new Category(),function (Form $form){
            $form->text('title');
            $form->number('sort');
            // 只查一级
            $form->select('parent_id')->default(51);
            $form->image('cover_img');
        });
    }
}