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;
use Dcat\Admin\Show;

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

                $tree->branch(function ($branch) {
                    $src = $branch['cover_img_url'];
                    $logo = "<img src='$src' style='margin-left: 20px; max-width:35px;max-height:35px' class='img'/>";
                
                    return "{$branch['id']} - {$branch['title']}  $logo";
                });

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

    public function form()
    {
        return Form::make(new Category(),function (Form $form){
           
            // 只查一级
            $parentList = Category::getCategoryArray([['parent_id','=',0]],[0=>'顶级']);

            $form->select('parent_id')->default(0)->options($parentList);
            $form->text('title');
            $form->image('cover_img');
            
            $form->number('sort');

            $form->disableResetButton();
            $form->disableViewCheck();
            $form->disableEditingCheck();
            $form->disableCreatingCheck();
        });
    }

    
    /**
     * Make a show builder.
     *
     * @param mixed $id
     *
     * @return Show
     */
    protected function detail($id)
    {
        return Show::make($id, new Category(), function (Show $show) {

            $show->field('parent_id');
            $show->field('title');
            $show->field('cover_img')->image();
            $show->field('sort');
            $show->field('status');
        });
    }
}