'mongodb nested schema - How to query a dynamic key

I have the following document structure,

    {
  "_id": "site1",
  "loc_layout": [
    {
      "dynamic_key1": [
        {
          "type": "Feature",
          "geometry": {
            "type": "Point",
            "coordinates": [
              80.05204336806904,
              13.131032427538385
            ]
          },
          "properties": {
            "site": "site1",
            "type": "gate",
            "location": "sgate1"
          }
        }
      ],
      "dynamic_key2": [
        {
          "type": "Feature",
          "geometry": {
            "type": "Point",
            "coordinates": [
              80.05204336804904,
              13.13103242754358
            ]
          },
          "properties": {
            "site": "site1",
            "type": "gate",
            "location": "sgate2"
          }
        },
        {
          "type": "Feature",
          "geometry": {
            "type": "Point",
            "coordinates": [
              80.05204336807904,
              13.13103242753985
            ]
          },
          "properties": {
            "site": "site1",
            "type": "gate",
            "location": "sgate3"
          }
        }
      ]
    }
  ]
}

Above "dynamic_key1" & "dynamic_key2" are the dynamic key attributes. How to use this dynamic key to retrieve the required objects as an array.

I have tried with the below query,

collection.aggregate([
  {
    "$unwind": "$loc_layout"
  },
  {
    "$match": {
      "_id": "site1",
      "loc_layout.dynamic_key1.properties.location": "sgate1"
    }
  },
  {
    "$project": {
      "loc_layout": 1
    }
  }
])

The expected result is,

{
  "_id": "site1",
  "location_layout": [
    {
      "dynamic_key1": [
        {
          "type": "Feature",
          "geometry": {
            "type": "Point",
            "coordinates": [
              80.05204336806904,
              13.131032427538385
            ]
          },
          "properties": {
            "site": "site1",
            "type": "gate",
            "location": "sgate1"
          }
        }
      ]
    }
  ]
}
mongodbaggregate


Solution 1:[1]

You only need to $project the right field at the end, and no need for an $unwind too, this query get the result you're aiming to:

db.collection.aggregate([
  {
    "$match": {
      "_id": "site1",
      "loc_layout.dynamic_key1.properties.location": "sgate1"
    }
  },
  {
    "$project": {
      "loc_layout.dynamic_key1": 1
    }
  }
])

You could have a look on attribute pattern btw as storing dynamic fields isn't a good practice when you need to filter on their content since you can create index on them

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Ayoub

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