具有多层嵌套数组的mongoDB查询文档

Question

`

{
    "sections": [
        {
            "desc": "no flow ID",
            "sectionObj": [
                {
                    "smartFlowIdList": []
                }
            ]
        },
        {
            "desc": "has flow ID",
            "sectionObj": [
                {
                    "smartFlowIdList": [
                        "smartFlowId1",
                        "smartFlowId2"
                    ]
                }
            ]
        
    ]
}

// Query document to see if any of the sections[].sectionObj[].smartFlowIdList has at least a flowId1  
// in this case: it is True since [   "smartFlowId1", "smartFlowId2" ] exits

`

我需要使用MongoDB shell命令查询此文档。

我已经尝试过查看$[]、$all和挖掘mongo文档，但似乎都没用。任何想法都是赞赏，谢谢！

Answer 1

一种选择是每个嵌套级别迭代两次，并计算最后一个嵌套级别中的项目。$match计数大于 0 的文档：

db.collection.aggregate([
  {$match: {$expr: 
      {$gt: [
          {$sum: {$map: {
                input: "$sections",
                as: "external",
                in: {$sum: [
                    {$reduce: {
                        input: "$$external.sectionObj",
                        initialValue: 0,
                        in: {$sum: ["$$value", {$size: "$$this.smartFlowIdList"}]}
                      }
                    }
                  ]
                }
          }}},
          0
      ]}
  }}
])

看看它是如何在操场上工作的例子