多个 Laravel 雄辩的关系

Question

我被堆积在 laravel 雄辩的关系中。这是场景：

我的数据库中有4 tables：
Categories,
Courses,
Lessons，和
Lesson_items.

我有3 more tables:
category_course,
course_lesson，和
lesson_item_lesson.

现在，我有这些代码：

Category.php - 型号

class Category extends Model
{
    public function courses(){
        return $this->belongsToMany('App\Course');
    }
}

routes.php - 路线

Route::get('/category/{id}', [
    'uses' => 'LearnController@getCategories'
]);

MyController.php - 控制器

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\Http\Requests;
use App\Http\Controllers\Controller;
use App\Category;
use App\Lesson;

class LearnController extends Controller
{
    public function getCategories($id){
        $categories = Category::find($id);
        $lessons = Lesson::find($categories);
        return view('categories', compact('categories', 'lessons'));
    }
}

现在，我想要的结果是这样的：

真的需要你们的帮助。

Answer 1

你需要nested eager laoding

Category.php

class Category extends Model
{
    public function courses(){
        return $this->belongsToMany('App\Course');
    }
}

Course.php

class Course extends Model
{
    public function lessons(){
        return $this->belongsToMany('App\Lesson');
    }
}

Lesson.php

class Lesson extends Model
{
    public function lessonItems(){
        return $this->belongsToMany('App\LessonItem');
    }
}

LessonItem.php

class LessonItem extends Model
{
    public function lessons(){
        return $this->belongsToMany('App\Lesson');
    }
}

然后在控制器中

class LearnController extends Controller
{
    public function getCategories($id){
        $categories = Category::with('courses.lessons.lessonItems')->find($id);
        return view('categories', compact('categories'));
    }
}

编辑

你需要某种这种结构

@foreach ($category->courses as $course) {
    @foreach ($course->lessons as $lesson) {
        @foreach ($lesson->lessonItems as $item) {

        @endforeach
    @endforeach
@endforeach