如何将school_id更改为int以保存在数据库中？

Question

如何将school_id更改为int以保存在数据库中？我在laravel和ajax中保存到数据库时遇到问题。我想school_id更改为变量（我认为）以进行保存。当我存储在数据库中时，网络标签中出现500错误。

我的代码在这里

<script type="text/javascript">
    $("#schools").submit(function (event) {
        event.preventDefault();
        province_id = $('#province_id').val();
        city_id = $('#city_id').val();
        center_id = $('#center_id').val();

        $.post("{{ route('schools-list.store') }}", {province_id:province_id, city_id:city_id, center_id:center_id}, function (data_school) {
            var school_id = {school_id: data_school.id} ;
            console.log(school_id);
        });
    });
</script>

控制器

public function store(Request $request, SchoolsList $schoolsList)
{
    if($request->ajax()) {
        $activity = new Activity();
        $activity->school_id = $request->school_id;
        $activity->cluster_id = $request->cluster_id;
        $activity->group_id = $request->group_id;
        $activity->save();
        return response()->json(['data_activity' => $request->all(), 'id' => $activity->id]);
    }
}