获取嵌套的关系数据$ lookup

Question

我有收藏页面，并且页面上有许多小部件：

页面集合：

_id
name
slug,
widget_codes

小工具集合：

_id
name
code
type
product_ids
category_ids

产品集合：

_id
name
type

类别集合：

_id
name
type

我这样检索数据：

public function getData($page) {
    return $page->raw(function ($collection) use ($page) {
        return $collection->aggregate([
            [
                '$lookup' => [
                    'from'         => 'widgets',
                    'localField'   => 'widget_codes',
                    'foreignField' => 'code',
                    'as'           => 'widgets',
                ]
            ],
            [
                '$match' => ['slug' => $page->slug]
            ]
        ]);
    });
}

它非常完美，现在可以获取小部件数据，我想使用该小部件具有product_ids和category_ids的小部件来获取产品和类别数据。

Answer 1

您可以使用pipeline in $lookup对多个表进行子查询

 public function getData($page) {
    return $page->raw(function ($collection) use ($page) {
      return $collection->aggregate([
          [
            '$match' => ['slug' => $page->slug]
          ],
          [
              '$lookup' => [
                  'from'         => 'widgets',
                  "let"=> [ "widget_codes"=> "$widget_codes" ],
                  "pipeline"=> [
                    [ "$match"=> [ "$expr"=> [ "$in"=> ["$_id", "$$widget_codes"] ]]],
                    [
                        '$lookup' => [
                            'from'         => 'category',
                            'localField'   => 'category_ids',
                            'foreignField' => '_id',
                            'as'           => 'categories',
                        ]
                    ],
                    [
                        '$lookup' => [
                            'from'         => 'product',
                            'localField'   => 'product_ids',
                            'foreignField' => '_id',
                            'as'           => 'products',
                        ]
                    ]
                  ],
                  'as'           => 'widgets',
              ]
          ]
      ]);
    });
}