例如一個學校，學校有許多年級，年級有許多班級，班級裡有許多老師，那麼這種多級的多對一該怎麼實現呢？

1.先設定他們的Model

學校的： School.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class schoolClass extends Model
{
    protected $table = 'schools';

  public function hasManyGrades( 
   {
     return $this->hasMany('App\Grade', 'school_id', 'id');
   }
}
 

年級的：Grade.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Grade extends Model
{
    protected $table = 'grades';

    public function hasManyClasses()
		{
		    return $this->hasMany('App\schoolClass', 'grade_id', 'id');
		}
}

班級的：schoolSchool.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class schoolClass extends Model
{
    protected $table = 'jjxiao_classes';

    public function hasManyTeachers()
		{
		    return $this->hasMany('App\Teacher', 'class_id', 'id');
		}
}
 

老師的：Teacher.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Teacher extends Model
{
  protected $table = 'jjxiao_teacher_staffs';
   
}

 public function index(){
        $id=1;
        $school=School::find($id);
        $grades=$school->hasManyGrades()->get();//找到所有的年級
        
        foreach($grades as $g){
            $classes[]=$g->hasManyClasses()->get();   //每個年級找到所對應的班級    
        }
        
        foreach ($classes as $cl) {
            foreach($cl as $c){
                $teachers[]=$c->hasManyTeachers()->get(); //每個班級找到老師
            }
        }

        foreach ($teachers as $te) {  //給陣列脫維
            foreach($te as $t){
               $teacher[]=$t;
            }
        }
        return view('home.myschool_teacher.index')
            ->withGrade($grades)
            ->withTeacher($teacher);
    }