我该如何处理这个错误：未定义的偏移量：0

Question

I'm producing an online school platform and in part of it student can see it's classes with their informations..but the related function return this error : Undefined offset: 0 (View: C:\\xampp\\htdocs\\OnlineSchool\\resources\\views\\admin\\student\\ClassReport.blade.php)

there are some relations between models My Models:

USER(students and teachers) ، LEVEL(level of classes) ، Classroom.

=> there is a many to many relation between student and classroom (pivot table)

please save me from this stupid error user:

    class User extends Authenticatable
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'email', 'password','image','level','code_meli',
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];

    /**
     * The attributes that should be cast to native types.
     *
     * @var array
     */
    protected $casts = [
        'email_verified_at' => 'datetime',
    ];

   public function classroom(){
        return $this->hasMany  (classroom::class);
    }

    public function ClassRoomStudent(){
        return $this->belongsToMany (classroom::class ,'classroom_user','user_id','classroom_id');
    }
}

classroom:

class classroom extends Model
{
    protected $fillable = [
        'title', 'teacher_id', 'level_id','day','time','price',
    ];

    public function Student(){
        return $this->belongsToMany (user::class ,'classroom_user','classroom_id','user_id');
    }

    public function level(){
        return $this->belongsTo (level::class );
    }
    public function teacher(){
        return $this->belongsTo (user::class );
    }

}

level :

class level extends Model
{
    protected $fillable = [
        'title',
    ];

    public function classroom(){
        return $this->hasMany (classroom::class);
    }
    public function exam(){
        return $this->hasMany (exam::class);
    }
}

and my function in controller:

public function MyClasses(){
    $student_id=auth ()->user ()->id;
    $classrooms=classroom::with ('level','teacher','factor')->wherehas('student',function ($q) use($student_id){
        $q->where('id',$student_id);
    })->get();
     
    return view ('admin.student.ClassReport',compact ('classrooms','student_id'));
}

at the end .. my blade:

 @foreach($classrooms as $class)
                    <tr>

                        <td>{{$i++}}</td>
                        <td>{{$class->title}}</td>
                        <td>{{$class->teacher[0]->name}}</td>
                        .
                        .
                        .
                        .
                    </tr>
            @endforeach 

Answer 1

Classroom 只属于一位老师，不需要使用 de 零索引，只需输入 $class->teacher->name