Question

我正在努力编写一个聚合管道，以按其_id查找嵌套文档并返回特定名称，而不会覆盖数据中现有的键/值。我已经设法对嵌套数组执行此操作，但是无法对嵌套在嵌套数组中的数组执行此操作。

所以我想查找每种成分和每个子成分的_id并将它们与已经存在的这些成分的数据合并（即数量，度量）。

这是我到目前为止的内容： https://mongoplayground.net/p/ft4oIMm_8wg

产品集合：

[
    {
      "_id": {
        "$oid": "5ecf269bceb735416db0b329"
      },
      "id": 36,
      "title": "Product 1",
      "description": {
        "generalInformation": "Some information",
        "activeIngredients": [
          {
            "_id": 1636,
            "qty": 133.5,
            "measure": "µg",
            "subIngredient": [
              {
                "_id": 1626,
                "qty": 16.6,
                "measure": "µg"
              }
            ],
            
          },
          {
            "_id": 1234,
            "qty": 133.5,
            "measure": "µg",
            "subIngredient": [
              {
                "_id": 1122,
                "qty": 16.6,
                "measure": "µg"
              },
              {
                "_id": 1212,
                "qty": 16.6,
                "measure": "µg"
              }
            ],
            
          },
          
        ]
      },
      
    },
    {
      "_id": {
        "$oid": "5ecf269bceb735416db0b346"
      },
      "id": 36,
      "title": "Product 2",
      "description": {
        "generalInformation": "Some information",
        "activeIngredients": [
          {
            "_id": 1234,
            "qty": 133.5,
            "measure": "µg",
            "subIngredient": [
              {
                "_id": 1122,
                "qty": 16.6,
                "measure": "µg"
              }
            ],
            
          },
          {
            "_id": 1234,
            "qty": 133.5,
            "measure": "µg",
            "subIngredient": [
              {
                "_id": 1122,
                "qty": 16.6,
                "measure": "µg"
              },
              {
                "_id": 1212,
                "qty": 16.6,
                "measure": "µg"
              }
            ],
            
          },
          
        ]
      },
      
    }
  ]

成分收集：

[
    {
      "_id": 1234,
      "name": "Ingredient 1",
      
    },
    {
      "_id": 1122,
      "name": "Ingredient 2",
      
    },
    {
      "_id": 1212,
      "name": "Ingredient 3",
      
    },
    {
      "_id": 1636,
      "name": "Ingredient 4",
      
    },
    {
      "_id": 1626,
      "name": "Ingredient 5",
      
    }
  ]

应该返回什么：

[
  {
    "_id": ObjectId("5ecf269bceb735416db0b329"),
    "title": "Product 1"
    "description": {
      "activeIngredients": {
        "_id": 1636,
        "measure": "µg",
        "name": "Ingredient 4",
        "qty": 133.5,
        "subIngredient": [
          {
            "_id": 1626,
            "measure": "µg",
            "qty": 16.6
          }
        ]
      },
      "generalInformation": "Some information"
    },
    "ingredients": [
      {
        "_id": 1636,
        "measure": "µg",
        "name": "Ingredient 4",
        "qty": 133.5,
        "subIngredient": [
          {
            "_id": 1626,
            "measure": "µg",
            "qty": 16.6,
            "name": "Ingredient 2"
          }
        ]
      },
      {
        "_id": 1234,
        "measure": "µg",
        "name": "Ingredient 1",
        "qty": 133.5,
        "subIngredient": [
          {
            "_id": 1122,
            "measure": "µg",
            "qty": 16.6,
            "name": "Ingredient 2"
          },
          {
            "_id": 1212,
            "measure": "µg",
            "qty": 16.6,
            "name": "Ingredient 2"
          }
        ]
      }
    ]
    
  },
  
]

我当前的管道：

[
  {
    "$unwind": {
      "path": "$description.activeIngredients",
      "preserveNullAndEmptyArrays": false
    }
  },
  {
    "$lookup": {
      "from": "ingredients",
      "localField": "description.activeIngredients._id",
      "foreignField": "_id",
      "as": "description.activeIngredients.name"
    }
  },
  {
    "$addFields": {
      "description.activeIngredients.name": {
        "$arrayElemAt": [
          "$description.activeIngredients.name.name",
          0
        ]
      }
    }
  },
  {
    "$group": {
      "_id": "$_id",
      "ingredients": {
        "$push": "$description.activeIngredients"
      },
      "description": {
        "$first": "$description"
      },
      "title": {
        "$first": "$title"
      }
    }
  },
  {
    "$lookup": {
      "from": "ingredients",
      "localField": "ingredients.subIngredient._id",
      "foreignField": "_id",
      "as": "subIngredients"
    }
  }
]

感谢任何帮助。谢谢。

Answer 1

您相距不远，您可以通过多种不同的方式来获得此结果，其中一种方法是仅QueryHandler $unwind数组，subingredients上，最后添加另一个$lookup阶段以重组文档。

正如您已经清楚地表明，您知道如何做所有这些事情，我将展示一种利用$map，$indexOfArray和Mongo的v3.6 $lookup语法等运算符的不同方式。 >

该策略不是展开子数组，我们只是$group所有相关子成分，然后使用我指定的运算符“合并”两个数组。

即服用：

$lookup

并使其成为：

[ {id: 5, name: "name"} ];
[ {id: 5, qty: 25} ]

这是我们的操作方式：

[ {id: 5, name: "name", qty: 25} ]

MongoPlayground

聚合管道以查找和合并嵌套的文档

1 个答案: