如何根据查询结果中的字段创建分组结构？答案

【问题标题】：How create a grouped structure based off of a field in a query result?如何根据查询结果中的字段创建分组结构？
【发布时间】：2016-01-12 16:41:21
【问题描述】：

我正在尝试在 cakephp3 中按年份分组。我能够使用以下方式，但它仍然没有按年份分组（我想要的方式。）

$query = $this->Alerts->query();
$year = $query->func()->year([
    'added_on' => 'literal'
]);

$month = $query->func()->monthname(['added_on' => 'literal']);
$monthAlertsCount = $query->func()->count($month);
$data = $query
    ->select([
        'year' => $year,
        'month' => $month,
        'count' => $monthAlertsCount
    ])
    ->group($year)
    ->group($month);

$status = "success";
$this->set('response', $status);
$this->set('year', $data);
$this->set('_serialize', ['response','year']);

当前输出如下：

{

    "response":"success",
    "year":[
        {
            "year":"2013",
            "month":"November",
            "count":"1"
        },
        {
            "year":"2014",
            "month":"February",
            "count":"2"
        },
        {
            "year":"2014",
            "month":"January",
            "count":"3"
        },
        {
            "year":"2015",
            "month":"December",
            "count":"6"
        },
        {
            "year":"2015",
            "month":"February",
            "count":"3"
        },
        {
            "year":"2015",
            "month":"January",
            "count":"4"
        },
        {
            "year":"2016",
            "month":"January",
            "count":"83"
        }
    ]

}

预期输出：

{

    "response":"success",
    "year":[
        {
            "2013":[
                {
                    "month":"November",
                    "count":"1"
                }
            ],
            "2014":[
                {
                    "month":"February",
                    "count":"2"
                },
                {
                    "month":"January",
                    "count":"3"
                }
            ],
            "2015":[
                {
                    "month":"December",
                    "count":"6"
                },
                {
                    "month":"February",
                    "count":"3"
                },
                {
                    "month":"January",
                    "count":"4"
                }
            ],
            "2016":[
                {
                    "month":"January",
                    "count":"83"
                }
            ]
        }
    ]

}

谁能帮我在 cakephp3 中得到预期的输出？

【问题讨论】：

标签： cakephp orm query-builder cakephp-3.1

【解决方案1】：

使用集合方法groupBy() - 请记住，查询是集合对象（有点）！

$data = $query
    ->select([
        'year' => $year,
        'month' => $month,
        'count' => $monthAlertsCount
    ])
    ->group($year)
    ->group($month)
    ->groupBy('year');

这将创建所需的分组结构，但它不会从各个行中删除 year 字段，如果您希望删除它们，请使用映射器，例如

// ...
->groupBy('year')
->map(function ($rows) {
    foreach ($rows as &$row) {
        unset($row['year']);
    }
    return $rows;
});

另见

【讨论】：

嗨，感谢您的回复，它几乎接近我想要的，但我仍然无法删除 year ->groupBy('year') ->map(function ($row) { unset($row['year']); return $row; });不会从输出中删除年份
@AkshayMalhotra 忘记了映射器不会遍历组...检查更新的代码示例。