SQLSTATE [23000]：违反完整性约束：1452无法添加laravel

Question

我收到此错误：

  

SQLSTATE [23000]：违反完整性约束：1452无法添加或   更新子行：外键约束失败   （prj_tvto.activities，约束活动_school_id_foreign FOREIGN   KEY（school_id）参考学校（id））（SQL：插入活动   （school_id，cluster_id，group_id，updated_at，created_at）值（0，   2，3，2018-08-14 05:02:28，2018-08-14 05:02:28））

在控制器中

public function store(Request $request, SchoolsList $schoolsList)
{
    if($request->ajax()) {
        $activity = new Activity();
        $activity->school_id = intval($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]);
    }
}

还有Ajax

        var school_id = {school_id: data_school.id} ;
        console.trace(school_id);

我正在使用laravel 5.4