slake-school-service/app/Models/Activity.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 Activity extends Model
{
    use SoftDeletes;

    protected $fillable = [
        'code',
        'title',
        'activity_type_dict_item_id',
        'quota',
        'event_start_date',
        'event_end_date',
        'signup_start_date',
        'signup_end_date',
        'location',
        'intro_html',
        'progress_status',
        'published',
        'remark',
        'sort',
    ];

    protected $casts = [
        'event_start_date' => 'date',
        'event_end_date' => 'date',
        'signup_start_date' => 'date',
        'signup_end_date' => 'date',
        'quota' => 'integer',
        'progress_status' => 'integer',
        'published' => 'integer',
        'sort' => 'integer',
    ];

    public function activityTypeItem(): BelongsTo
    {
        return $this->belongsTo(DictItem::class, 'activity_type_dict_item_id');
    }

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

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