method does not exist laravel

Question

hey guys i have this problem in my code , i dont know why is showing this error:

Method Illuminate\Database\Eloquent\Collection::students does not exist.

i tried to make many to many relation and this is my controller function:

public function attach_skill(Request $request) {


            foreach($request->skills as $id){
                dd(Skill::find($request->skills)->students()->attach($request->students));
                return "done";
              }

    }

and this is my student model code:

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Laravel\Sanctum\HasApiTokens;
use Illuminate\Foundation\Auth\User as Authenticatable;
use App\Models\Task;
use App\Models\Skill;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;

class Students extends Authenticatable
{
    use HasFactory, HasApiTokens;
    protected $fillable = [
        'name',
        'student_id',
        'phone',
        'password',
        'email',
        'major',
        'GPA',
        'Department',
        'address',
    ];

    protected $hidden = [
        'password',
        'remember_token',
        'email',
        'natioal_id'
    ];

    public $table = "students";
    protected $primaryKey = 'student_id';

    public function tasks() {
        return $this->belongsToMany(Task::class,'student_task','task_id','student_id');
    }

    public function taskk() {
        return $this->belongsToMany(Task::class,'student_task','student_id','task_id');
    }

    public function skill() {
        return $this->belongsToMany(Skill::class, 'student_skill', 'skill_id', 'student_id');
    }

    public function skilll() {
        return $this->belongsToMany(Skill::class, 'student_skill', 'student_id','skill_id');
    }

}

and this is my skill model code:

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use App\Models\Students;

class Skill extends Model
{
    use HasFactory;

    protected $fillable = [
        'skill_type',
    ];

    protected $primaryKey = 'skill_id';
    public function students() {
        return $this->belongsToMany(Students::class,'student_skill','skill_id','student_id');
    }

    public function skilll() {
        return $this->belongsToMany(Skill::class, 'student_skill', 'student_id','skill_id');
    }
    public $timestamps = false;

}

i want students and skills request in array becuse i have my skills and many students.

Answer 1

Because you're passing an array to find() method that is wrong, pass $id instead of $request->skills, please do this if you're iterating in loop,

public function attach_skill(Request $request) {
    foreach($request->skills as $id){
      dd(Skill::find($id)->students()->attach($request->students));
      return "done";
    }
}