如何在MongoDB中的集合下查找同一个文档

Question

我在 MongoDB 中有以下文档 [更新：缩短了文档]

{
  "sections": [
    {
      "_id": {
        "$oid": "64cbeb62b669cd29a5719a8f"
      },
      "categories": [
        {
          "measureValues": [
            "64cbeb62b669cd29a5719a95",
            "64cbeb62b669cd29a5719a99"
          ]
        }
      ]
    }
  ],
  "measures": [
    {
      "_id": {
        "$oid": "64cbeb62b669cd29a5719a93"
      },
      "name": {
        "64cbeb62b669cd29a5719a92": {
          "nodeType": "nodeName",
          "value": "measure-1"
        }
      },
      "measureValues": [
        {
          "_id": {
            "$oid": "64cbeb62b669cd29a5719a95"
          },
          "measureValues": {
            "nodeName": {
              "64cbeb62b669cd29a5719a94": {
                "nodeType": "nodeName",
                "value": "measureValue",
                "_class": "com.myapp.cqrsdemo.model.DataObj"
              }
            },
            "comment": {
              "64cbeb62b669cd29a5719a97": {
                "nodeType": "comment",
                "value": "this is a comment",
                "_class": "com.myapp.cqrsdemo.model.DataObj"
              }
            }
          },
          "categoriesIds": [
            "64cbeb62b669cd29a5719a91"
          ],
          "measureName": "measure-1"
        },
        {
          "_id": {
            "$oid": "64cbeb62b669cd29a5719a99"
          },
          "measureValues": {
            "nodeName": {
              "64cbeb62b669cd29a5719a98": {
                "nodeType": "nodeName",
                "value": "measureValue",
                "_class": "com.myapp.cqrsdemo.model.DataObj"
              }
            },
            "date": {
              "64cbeb62b669cd29a5719a9b": {
                "nodeType": "date",
                "value": "2023-02-02",
                "_class": "com.myapp.cqrsdemo.model.DataObj"
              }
            }
          },
          "categoriesIds": [
            "64cbeb62b669cd29a5719a91"
          ],
          "measureName": "measure-1"
        }
      ]
    }
  ],
  "_class": "com.myapp.cqrsdemo.model.ProjectGroup"
}

我想获取“measures”下的“measureValues”，其中“measureValues”的 id 与类别下的measureValues 的 id 匹配。我想在类别下包含measureValue 对象，而不仅仅是Id。

我怎样才能做到这一点？我尝试编写聚合管道，但失败了。

我的输出应如下所示。

{
  "sections": [
    {
      "_id": {
        "$oid": "64cbeb62b669cd29a5719a8f"
      },
      "categories": [
        {
          "measureValues": [
            {
              "_id": {
                "$oid": "64cbeb62b669cd29a5719a95"
              },
              "measureValues": {
                "nodeName": {
                  "64cbeb62b669cd29a5719a94": {
                    "nodeType": "nodeName",
                    "value": "measureValue",
                    "_class": "com.myapp.cqrsdemo.model.DataObj"
                  }
                },
                "comment": {
                  "64cbeb62b669cd29a5719a97": {
                    "nodeType": "comment",
                    "value": "this is a comment",
                    "_class": "com.myapp.cqrsdemo.model.DataObj"
                  }
                }
              },
              "categoriesIds": [
                "64cbeb62b669cd29a5719a91"
              ],
              "measureName": "measure-1"
            },
            {
              "_id": {
                "$oid": "64cbeb62b669cd29a5719a99"
              },
              "measureValues": {
                "nodeName": {
                  "64cbeb62b669cd29a5719a98": {
                    "nodeType": "nodeName",
                    "value": "measureValue",
                    "_class": "com.myapp.cqrsdemo.model.DataObj"
                  }
                },
                "date": {
                  "64cbeb62b669cd29a5719a9b": {
                    "nodeType": "date",
                    "value": "2023-02-02",
                    "_class": "com.myapp.cqrsdemo.model.DataObj"
                  }
                }
              },
              "categoriesIds": [
                "64cbeb62b669cd29a5719a91"
              ],
              "measureName": "measure-1"
            }
          ]
        }
      ]
    }
  ],
  "_class": "com.myapp.cqrsdemo.model.ProjectGroup"
}

Answer 1

一个选项是：

1. 创建一个 var

   measureValuesArr

   并在其中存储所有

   measureValues

    下所有 

   measures
的单个展平数组
2. 由于

   sections.categories.measureValues

   是一个双重嵌套数组（在数组上的数组内部），因此使用 double

   $map

   来进入它的所有实例。
3. 使用

   $arrayElemAt

   和

   $indexOfArray

   来查找

   measureValues

    内匹配的 

   measureValuesArr
项目

db.collection.aggregate([
  {$set: {
      sections: {$let: {
          vars: {measureValuesArr: {$reduce: {
                input: "$measures",
                initialValue: [],
                in: {$concatArrays: ["$$value", "$$this.measureValues"]}
          }}},
          in: {$map: {
              input: "$sections",
              as: "s",
              in: {$mergeObjects: [
                  "$$s",
                  {categories: {$map: {
                        input: "$$s.categories",
                        as: "c",
                        in: {$mergeObjects: [
                            "$$c",
                            {measureValues: {$map: {
                                  input: "$$c.measureValues",
                                  as: "m",
                                  in: {$arrayElemAt: [
                                      "$$measureValuesArr",
                                      {$indexOfArray: [
                                          "$$measureValuesArr._id",
                                          {$toObjectId: "$$m"}
                                      ]}
                                  ]}
                            }}}
                        ]}
                  }}}
              ]}
          }}
      }}
  }}
])

查看它在 playground 示例中的工作原理