math_cms/app/Models/Teacher.php

<?php

namespace App\Models;

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

class Teacher extends Model
{
    use HasFactory;

    protected $table = 'teachers';

    protected $primaryKey = 'teacher_id';

    public $incrementing = false;

    protected $keyType = 'string';

    public $timestamps = true;

    protected $fillable = [
        'teacher_id',
        'teacher_string_id',
        'user_id',
        'name',
        'subject',
    ];

    /**
     * 对应老师用户信息。
     */
    public function user(): BelongsTo
    {
        // teachers.user_id 对应 users.user_id（而非默认的 id）
        return $this->belongsTo(User::class, 'user_id', 'user_id');
    }

    /**
     * 老师下的学生。
     */
    public function students(): HasMany
    {
        return $this->hasMany(Student::class, 'teacher_id', 'teacher_id');
    }
}