ospro-api-laravel/app/Models/AssignMaterial.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use App\Models\RequestMaterial;
use App\Models\Activity;

class AssignMaterial extends Model
{
    protected $table = 'assign_material_to_activity', $guarded = ['id'];

    const CREATED_AT = 'created_at';
    const UPDATED_AT = 'updated_at';

    protected $casts = [
        'id' => 'integer',
        'budget' => 'string',
    ];

    public static function boot()
    {
        parent::boot();

        static::created(function ($data) {
            $activity = Activity::find($data->activity_id);
            $material = RequestMaterial::where("id", $data->material_id)->first();
            $activity->rencana_biaya += floatval($material->price) * floatval($data->qty_planning);
            $activity->save();
        });

        static::deleted(function ($data) {
            $activity = Activity::where('id', $data->activity_id)->first();
            $activity->rencana_biaya -= floatval($data->budget) * floatval($data->qty_planning);
            $activity->save();
        });
    }
}