Question

我有一个问题表和另一个包含Answers的表。一个问题有很多答案，答案属于一个问题。这些关系已在问答模型中定义，并按预期工作。

但是，当我试图通过答案得到一堆问题时，Eloquent会返回一个空数组。

return Question::with('answers')
                ->where('category_id', $input['category'])
                ->take($input['num_questions'])
                ->orderBy(DB::raw('RAND()'))
                ->get();

我收到以下回复......

{
"id": "1",
"category_id": "1",
"question": "Why did the chicken cross the road?",
"feedback": "Why did you ask that?",
"created_at": "2014-04-24 16:57:48",
"updated_at": "2014-04-24 16:57:48",
"answers": []
},
{
"id": "2",
"category_id": "1",
"question": "How awesome is Laravel?",
"feedback": "That's debatable.",
"created_at": "2014-04-24 16:57:48",
"updated_at": "2014-04-24 16:57:48",
"answers": []
}

打印原始查询时，我看到以下内容......

{
"query": "select * from `questions` where `category_id` = ? order by RAND() asc",
"bindings": [
    "1"
],
"time": 2.11
},
{
"query": "select `id`, `choice`, `correct` from `answers` where `answers`.`question_id` in (?, ?, ?, ?)",
"bindings": [
    "3",
    "4",
    "1",
    "2"
],
"time": 0.92
}

当我手动运行这些查询时，我会看到答案，但由于某些原因，laravel会显示一个空数组。为什么？我在这里做错了什么？

Answer 1

我手动选择了我想在模型中返回的字段。当您选择多行而不是单行时，这显然会中断。

    return $this->hasMany('Answers')->select(array('id', 'choice'));

从模型中删除 - ＆gt; select（）代码修复它。

Answer 2

首先从模型中删除 - ＆gt; select（）代码，然后执行：

return Question::with(array('answers'=>function($query)
            {
                $query->select(array('id', 'choice','question_id')); // question_id is mandatory because Laravel need it for mapping
            }))
            ->where('category_id', $input['category'])
            ->take($input['num_questions'])
            ->orderBy(DB::raw('RAND()'))
            ->get();

Laravel雄辩的关系

2 个答案: