math_cms/app/Models/Student.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;

class Student extends Model
{
    use HasFactory;

    protected $table = 'students';

    protected $primaryKey = 'student_id';

    public $incrementing = false;

    protected $keyType = 'int';

    protected $fillable = [
        'student_id',
        'name',
        'grade',
        'class_name',
        'teacher_id',
        'remark',
    ];

    protected $casts = [
        'created_at' => 'datetime',
        'updated_at' => 'datetime',
    ];

    public function teacher(): BelongsTo
    {
        return $this->belongsTo(Teacher::class, 'teacher_id', 'teacher_id');
    }

    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class, 'student_id', 'user_id');
    }
}