app-api/app/Http/Controllers/Course/CateController.php

<?php

namespace App\Http\Controllers\Course;

use Illuminate\Http\Request;
use App\Models\Course\Course;
use App\Models\Course\Cate;
use App\Http\Controllers\Controller;

class CateController extends Controller
{
    //获取分类
    public function getCate(Request $request)
    {
        $page_index=$request->input('page_index');
        $page_size=$request->input('page_size');
        $num=$page_size*($page_index-1);
        $pid=$request->input('pid');
        $count=Cate::query()->where('pid',$pid)->count();
        $list=Cate::query()->where('pid',$pid)
            ->withCount(['course'=>function($query){
                $query->where('state','1');
            }])
            ->orderBy('sort','desc')->orderBy('id','desc')
            ->skip($num)->take($page_size)
            ->get();
        if($pid==0){
            foreach($list as $key=>$val){
                $cate_id=Cate::query()->where('pid',$val->id)->pluck('id');
                $list[$key]->course_count=Course::where('state','1')->whereIn('c_id',$cate_id)->count();
            }
        }
        return $this->success_list($list,'',$count);
    }
}