如何在 mongodb 中重新组合我的展开项目？答案

【问题标题】：How do I re-group my unwind items back in mongodb?如何在 mongodb 中重新组合我的展开项目？
【发布时间】：2021-05-18 20:58:28
【问题描述】：

我正在构建一个看板，我需要将我的整个看板文档投影为一个缩小文档。

它是一个看板对象，列作为嵌入文档，卡片作为每列的子文档。

我有这个数据集：

{
  "_id": {
    "$oid": "609b2ab4c60588f6b0579259"
  },
  "title": "Entregas",
  "ownerId": "6026af58714618ac77356d2c",
  "columns": [
    {
      "headerText": "Backlog",
      "keyField": "Backlog",
      "cards": []
    },
    {
      "headerText": "Column 1",
      "keyField": "Column 1",
      "cards": [
        {
          "design": "default",
          "rank": 0,
          "labels": [
            {
              "color": "#61bd4f",
              "text": "",
              "active": false
            },
            {
              "color": "#eb5a46",
              "text": "",
              "active": true
            },
            {
              "color": "#f5dd29",
              "text": "",
              "active": false
            },
            {
              "color": "#ff9f1a",
              "text": "",
              "active": true
            },
            {
              "color": "#c377e0",
              "text": "",
              "active": true
            },
            {
              "color": "#0079bf",
              "text": "",
              "active": false
            }
          ],
          "description": "Ah valeyhjs",
          "_id": {
            "$oid": "609d3a63fc07b66ba8168215"
          },
          "title": "test2",
          "parentColumn": "Column 1",
          "creationDate": {
            "$date": "2021-05-13T14:40:35.497Z"
          },
          "updatedAt": {
            "$date": "2021-05-13T14:43:49.287Z"
          }
        },
        {
          "design": "default",
          "rank": 0,
          "labels": [
            {
              "color": "#61bd4f",
              "text": "",
              "active": false
            },
            {
              "color": "#eb5a46",
              "text": "",
              "active": false
            },
            {
              "color": "#f5dd29",
              "text": "",
              "active": false
            },
            {
              "color": "#ff9f1a",
              "text": "",
              "active": false
            },
            {
              "color": "#c377e0",
              "text": "",
              "active": false
            },
            {
              "color": "#0079bf",
              "text": "",
              "active": false
            }
          ],
          "description": "",
          "_id": {
            "$oid": "609e6ee8865e834d14bd1ff5"
          },
          "title": "xd",
          "parentColumn": "Column 1",
          "creationDate": {
            "$date": "2021-05-14T12:36:56.473Z"
          },
          "updatedAt": {
            "$date": "2021-05-14T12:36:56.473Z"
          }
        }
      ]
    },
    {
      "headerText": "Column 2",
      "keyField": "Column 2",
      "cards": [
        {
          "design": "default",
          "rank": 0,
          "labels": [
            {
              "color": "#61bd4f",
              "text": "",
              "active": false
            },
            {
              "color": "#eb5a46",
              "text": "",
              "active": false
            },
            {
              "color": "#f5dd29",
              "text": "",
              "active": false
            },
            {
              "color": "#ff9f1a",
              "text": "",
              "active": false
            },
            {
              "color": "#c377e0",
              "text": "",
              "active": false
            },
            {
              "color": "#0079bf",
              "text": "",
              "active": false
            }
          ],
          "description": "",
          "_id": {
            "$oid": "609d3984fc07b66ba8168214"
          },
          "title": "test",
          "parentColumn": "Column 2",
          "creationDate": {
            "$date": "2021-05-13T14:36:52.899Z"
          },
          "updatedAt": {
            "$date": "2021-05-13T14:36:52.899Z"
          }
        }
      ]
    }
  ],
  "creationDate": {
    "$date": "2021-05-12T01:09:09.000Z"
  },
  "updatedAt": {
    "$date": "2021-05-18T11:52:45.925Z"
  },
  "__v": 52
}

这是我的聚合

    [
    {
        '$match': {
            '_id': ObjectId('609b2ab4c60588f6b0579259')
        }
    }, {
        '$unwind': {
            'path': '$columns'
        }
    }, {
        '$unwind': {
            'path': '$columns.cards', 
            'preserveNullAndEmptyArrays': True
        }
    }, {
        '$project': {
            'title': 1, 
            'ownerId': 1, 
            'columns.headerText': 1, 
            'columns.keyField': 1, 
            'columns.cards.labels': 1, 
            'columns.cards.title': 1, 
            'columns.cards.parentColumn': 1, 
            'columns.cards._id': 1, 
            'columns.cards.attachments': {
                '$size': {
                    '$ifNull': [
                        '$columns.cards.attachments', []
                    ]
                }
            }, 
            'columns.cards.checkLists': {
                '$size': {
                    '$ifNull': [
                        '$columns.cards.checklLists', []
                    ]
                }
            }, 
            'columns.cards.activity': {
                '$size': {
                    '$ifNull': [
                        '$columns.cards.activity', []
                    ]
                }
            }, 
            'creationDate': 1, 
            'updatedAt': 1
        }
    }, {
        '$group': {
            '_id': '$_id', 
            'title': {
                '$first': '$title'
            }, 
            'ownerId': {
                '$first': '$ownerId'
            }, 
            'columns': {
                '$push': '$columns'
            }, 
            'creationDate': {
                '$first': '$creationDate'
            }, 
            'updatedAt': {
                '$first': '$updatedAt'
            }
        }
    }
]

我试图仅获取 Card 子文档中每个数组的大小。我的麻烦是我的最终文件使用了错误的卡片。我需要将它们归为一组与它们的父列。

【问题讨论】：

标签： mongodb mongoose aggregation-framework

【解决方案1】：

您可以尝试不使用$unwind 使用$map，

$map 迭代 columns 数组的循环
$map 迭代 cards 数组的循环
添加您的必填字段并使用$mergeObjects 与当前文档合并
$mergeObjects 合并 columns 和 cards 更新字段的当前文档

db.collection.aggregate([
  { "$match": { "_id": ObjectId("609b2ab4c60588f6b0579259") } },
  {
    $addFields: {
      columns: {
        $map: {
          input: "$columns",
          in: {
            $mergeObjects: [
              "$$this",
              {
                cards: {
                  $map: {
                    input: "$$this.cards",
                    in: {
                      $mergeObjects: [
                        "$$this",
                        {
                          attachments: {
                            $size: { $ifNull: ["$$this.attachments", []] }
                          }
                        },
                        {
                          checkLists: {
                            $size: { $ifNull: ["$$this.checkLists", []] }
                          }
                        },
                        {
                          activity: {
                            $size: { $ifNull: ["$$this.activity", []] }
                          }
                        }
                      ]
                    }
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
])

Playground

【讨论】：

我刚刚注意到我没有在示例数据集上放置附件、清单和活动数组。非常感谢您！