slake-school-service/app/Models/ActivitySession.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;
use Illuminate\Database\Eloquent\SoftDeletes;

class ActivitySession extends Model
{
    use SoftDeletes;

    protected $fillable = [
        'activity_id',
        'title',
        'starts_at',
        'ends_at',
        'venue',
        'capacity',
        'sort',
    ];

    protected $casts = [
        'starts_at' => 'datetime',
        'ends_at' => 'datetime',
        'capacity' => 'integer',
        'sort' => 'integer',
    ];

    public function activity(): BelongsTo
    {
        return $this->belongsTo(Activity::class);
    }

    public function signups(): HasMany
    {
        return $this->hasMany(ActivitySignup::class);
    }
}