Laravel评论分数计算代码任务调度正常，放入队列作业报错原因

核心原因是Laravel队列在序列化Eloquent模型时，不会保留withCount方法生成的临时动态属性。
你在调度任务中执行withCount('upVotes')、withCount('downVotes')得到的up_votes_count、down_votes_count是临时挂载在Comment模型实例上的属性，不属于模型的原生字段。当你把Comment模型传给Job后，Laravel会自动序列化模型仅保留主键信息，队列进程执行Job时会根据主键重新从数据库查询Comment实例，这时候原来预加载的count属性就丢失了，所以$item->up_votes_count为null，赋值给非空字段total_upvotes就触发了完整性约束错误。

• 方案1：仅传递评论ID到Job，在Job内部查询时加载count属性
  调度代码调整：

public function handle()
{
    Comment::where('created_at', '>', Carbon::now()->subDays(3))
        ->pluck('id')
        ->each(function ($id) {
            CalculateCommentScoreJob::dispatch($id);
        });
}

Job代码调整：

use Rank;

protected $commentId; 

public function __construct(int $commentId)
{
    $this->commentId = $commentId;
}

public function handle()
{
    $item = Comment::withCount('upVotes')
        ->withCount('downVotes')
        ->findOrFail($this->commentId);
    $item->total_upvotes = $item->up_votes_count;
    $item->total_downvotes = $item->down_votes_count;
    $item->total_score = $this->score($item->up_votes_count, $item->down_votes_count);
    $item->fuzzed_score = (int)round($item->total_score + (rand(0,22) / 100 ) * $item->total_score, 0);
    $item->save();
}

• 方案2：把count值作为单独参数传递给Job，避免重复查询
  调度代码调整：

public function handle()
{
    $comments = Comment::where('created_at', '>', Carbon::now()->subDays(3))
        ->withCount('upVotes')
        ->withCount('downVotes')
        ->get();

    $comments->each(function ($item) {
        CalculateCommentScoreJob::dispatch($item->id, $item->up_votes_count, $item->down_votes_count);
    });
}

Job代码调整：

use Rank;

protected $commentId;
protected $upVotesCount;
protected $downVotesCount;

public function __construct(int $commentId, int $upVotesCount, int $downVotesCount)
{
    $this->commentId = $commentId;
    $this->upVotesCount = $upVotesCount;
    $this->downVotesCount = $downVotesCount;
}

public function handle()
{
    $item = Comment::findOrFail($this->commentId);
    $item->total_upvotes = $this->upVotesCount;
    $item->total_downvotes = $this->downVotesCount;
    $item->total_score = $this->score($this->upVotesCount, $this->downVotesCount);
    $item->fuzzed_score = (int)round($item->total_score + (rand(0,22) / 100 ) * $item->total_score, 0);
    $item->save();
}

内容的提问来源于stack exchange，提问作者Felix