Laravel 如何通过 Eloquent 获取单个集合中每位教师的学生人数

发布于01月28日

老师有很多学生.当我显示教师列表时，我还想显示每个教师的学生计数.我怎样才能用口才做到这一点呢？

我可以从这里找到老师， $teacher= Teacher::where('teacher_status','active')->get();个

我可以从中找出学生人数 $student_count = Student::where('teacher_id','teachers.id')->count();个

如何组合这两个查询并在单个数组/集合中返回响应？

推荐答案

In your teacher model, create the relationship students:个

class Teacher extends Model
{
    public function students()
    {
        return $this->hasMany(Student::class, 'teacher_id');
    }
}

In your controller you can do the following:个

public function example(){
    $teachers = Teacher::where('teacher_status','active')->withCount('students')->get();
    
    return view('teacherViewExample', compact('teachers'));
}

In your view(教师视图示例):

<table>
  <thead>
    <tr>
      <th>Teacher Name</th>
      <th>Students Count</th>
    </tr>
  </thead>
  <tbody>
    @foreach($teachers as $teacher)
    <tr>
      <td>{{ $teacher->name }}</td>
      <td>{{ $teacher->students_count }}</td>
    </tr>
    @endforeach
  </tbody>
</table>

有关如何使用withCount()的完整文档，请点击此处:https://laravel.com/docs/9.x/eloquent-relationships#counting-related-models