CourseWork/database/seeders/DatabaseSeeder.php

<?php

namespace Database\Seeders;

use App\Enums\ScoreEnum;
use App\Models\Grade;
use App\Models\Lesson;
use App\Models\Student;
use App\Models\Subject;
use App\Models\Teacher;
use App\Models\User;
use Illuminate\Database\Seeder;

class DatabaseSeeder extends Seeder
{
    /**
     * Seed the application's database.
     */
    public function run(): void
    {
        $teachers = Teacher::factory(15)->create();
        $grades = Grade::factory(10)->create();
        $subjects = Subject::factory(10)->create();
        $scores = ScoreEnum::cases();

        $teachers->each(function ($teacher) {
            $user = User::factory()->create();
            $teacher->user()->save($user);
        });

        $grades->each(function ($grade) use ($subjects, $teachers, $scores){
            $grade->subjects()->sync($subjects);
            $grade->teachers()->sync($teachers);

            $students = Student::factory(10)->create([
                'grade_id' => $grade->id,
            ])->each(function ($student) use ($scores) {
                $user = User::factory()->create();
                $student->user()->save($user);
            });

            $lessons = Lesson::factory(30)->create([
                'grade_id' => $grade->id,
                'subject_id' => $grade->subjects->random()->id,
                'teacher_id' => $grade->teachers->random()->id,
            ]);

            $students->each(function ($student) use ($lessons, $scores) {
                $lessons->each(function ($lesson) use ($student, $scores) {
                    $student->lessons()
                        ->syncWithoutDetaching([$lesson->id => ['score' => $scores[array_rand($scores)]]]);
                });
            });
        });

        $subjects->each(function ($subject) use ($teachers) {
            $subject->teachers()->sync($teachers->random(2));
        });
    }
}