Mongodb $lookup嵌套数组对象的聚合

我有

category

集合，其中包含子类别嵌入对象。我需要编写聚合脚本，以便首次从该集合查找到

storelisting

集合。然后将storelisting字段添加到相应的子类别中

类别 门店列表 我需要查找集合上面的表单到storeListing集合。我还需要storeListing的所有字段

结果应该如下所示：

{
  "_id": "",
  "categoryName": "",
  "subCategories": [
    {
      "subCategoryId": "",
      "subCategoryName": "",
      "storeListingIds": [
        "1",
        "2"
      ],
      "storeListings":[
        {
          "_id": "1",
          "storeListingName": "",
          "storeListingUrl": "",
          "catalogueIds": [
            ""
          ],
          "_class": ""
        },
        {
          "_id": "2",
          "storeListingName": "",
          "storeListingUrl": "",
          "catalogueIds": [
            ""
          ],
          "_class": ""
        }
      ]
    },
    {
      "subCategoryId": "",
      "subCategoryName": "",
      "storeListingIds": [
        "3","4","5"
      ],
      "storeListings":[
        {
          "_id": "3",
          "storeListingName": "",
          "storeListingUrl": "",
          "catalogueIds": [
            ""
          ],
          "_class": ""
        },
        {
          "_id": "4",
          "storeListingName": "",
          "storeListingUrl": "",
          "catalogueIds": [
            ""
          ],
          "_class": ""
        },
        {
          "_id": "5",
          "storeListingName": "",
          "storeListingUrl": "",
          "catalogueIds": [
            ""
          ],
          "_class": ""
        }
      ]
    }
  ],
  "order": 2,
  "createdAt": {
    "$date": "2020-12-01T22:26:11.669Z"
  },
  "updatedAt": {
    "$date": "2021-04-27T17:17:25.442Z"
  },
  "_class": ""
}

解释

我们对嵌套的

storeListingId

执行

$lookup

，并将结果存储在

tmp

字段中

我们应用筛选并将

子类别

对象与

商店列表

值合并

注意：我们之所以使用

$mergeObjects

是为了避免命名

子类别中的每个字段

$map: {
    input: "$subCategories",
    as: "subCat",
    in: {
        subCategoryId:"$$subCat.subCategoryId",
        subCategoryName:"$$subCat.subCategoryName",
        storeListingIds: "$$subCat.storeListingIds",
        storeListening: {
            $filter: {
                input: "$tmp",
                cond: {
                  $in: [ "$$this._id", "$$subCat.storeListingIds" ]
                }
            }
        }
    }
}

---

试试这个：

db.category.aggregate([
  {
    $lookup: {
      from: "storelisting",
      localField: "subCategories.storeListingIds",
      foreignField: "_id",
      as: "tmp"
    }
  },
  {
    $addFields: {
      tmp: "$$REMOVE",
      subCategories: {
        $map: {
          input: "$subCategories",
          as: "subCat",
          in: {
            "$mergeObjects": [
              "$$subCat",
              {
                storeListings: {
                  $filter: {
                    input: "$tmp",
                    cond: {
                      $in: [ "$$this._id", "$$subCat.storeListingIds" ]
                    }
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
])

---

这个问题不够清楚。。你需要加入哪个系列？

storeListingName

和其他人是怎么来的？@varman我们有两个集合类别和storelisting，我们需要加入category和storelisting。要加入这个，我们需要检查“subCategories.storeListingIds”中的ID。storeListingName属性来自storeListing集合。这是storelisting集合的文档：{“_id”：“4”，“storeListingName”：“storeListingUrl”：“CatalogEIDS”：[“”]，“_类”：“}

$map: {
    input: "$subCategories",
    as: "subCat",
    in: {
        subCategoryId:"$$subCat.subCategoryId",
        subCategoryName:"$$subCat.subCategoryName",
        storeListingIds: "$$subCat.storeListingIds",
        storeListening: {
            $filter: {
                input: "$tmp",
                cond: {
                  $in: [ "$$this._id", "$$subCat.storeListingIds" ]
                }
            }
        }
    }
}

db.category.aggregate([
  {
    $lookup: {
      from: "storelisting",
      localField: "subCategories.storeListingIds",
      foreignField: "_id",
      as: "tmp"
    }
  },
  {
    $addFields: {
      tmp: "$$REMOVE",
      subCategories: {
        $map: {
          input: "$subCategories",
          as: "subCat",
          in: {
            "$mergeObjects": [
              "$$subCat",
              {
                storeListings: {
                  $filter: {
                    input: "$tmp",
                    cond: {
                      $in: [ "$$this._id", "$$subCat.storeListingIds" ]
                    }
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
])