返回快速加载关系 Laravel 的计数

Question

所以我有包含Stack 的Subject，其中包含Question。每个问题都有答案，我想统计每个Stack的答案，但我卡住了。

这是我正在尝试做的，我一直在摆弄的众多解决方案之一：

    $subjects = Subject::with(['stack.question', 'stack.answersCount'])->get();

    return $subjects;

Subject 模型有如下关系：

public function stack(){
    return $this->hasMany(Stack::class);
}

如果我们看一下Stack 模型中的关系是如何建立的：

public function question(){
    return $this->hasMany(Question::class);
}

public function answers(){
    return $this->hasMany(Answers::class);
}

public function answersCount(){
    return $this->answers()->selectRaw('answer, count(*) as aggregate')->groupBy('answer');
}

但是当我return $subjects时，answer_count是空的。

"answers_count": []

这很令人困惑，因为当我在 SQL 中运行相同的查询时，我得到非空结果。

select answer, count(*) as aggregate from `answers` where `answers`.`stack_id` in ('1', '6') group by `answer`

correct 9
wrong   4

那么我如何计算所有答案呢？并将它们分组？

Answer 1

删除 answersCount 关系 - 不再需要，因为您可以使用 withCount 方法：

$subjects = Subject::with([
    'stack.question', 
    'stack' => function ($q) {
        $q->withCount('answers');
    }
])->get();

// then on each subject you can call stack->answers_count
$subjects->first()->stack->answers_count

Answer 2

试试这个方法

$subjects = Subject::with(['stack.question', 'stack.answersCount'])->get();
$count = $subjects->answersCount->first()->aggregate;

//count varible will have the count now you can use it as you would like to 

return $subjects;

进一步挖掘可以找到here