how to query through hashmap data using mongo terminal

Question

I have data stored in following format in mongodb .. help me in knowing how can I write a query to find if the database has a particular id stored in one of the sheet or not

the structure of data is like the following :-

{
    "name": "abc",
    "linked_data": {
      "sheet 1": [
        "7d387e05d3f8180a",
        "8534sfjog904395"
      ],
      "sheet 2": [
        "7d387e05d3f8180a",
        "54647sgdsevey67r34"
      ]
    }
  }

for example if id "8534sfjog904395" is mapped with "sheet 1".. then it should return me this data where id is mapped with the sheet. I am passing id in the query and want to find inside linked_data and then all the sheets

ray · Accepted Answer · 2023-02-03 16:35:52Z

1

Using dynamic value as field name is considered as an anti-pattern and introduce unnecessary complexity to queries. Nevertheless, you can use $objectToArray to convert the linked_data into array of k-v tuples. $filter to get only the sheet you want. Finally, revert back to original structure using $arrayToObject

db.collection.aggregate([
  {
    "$set": {
      "linked_data": {
        "$objectToArray": "$linked_data"
      }
    }
  },
  {
    $set: {
      linked_data: {
        "$filter": {
          "input": "$linked_data",
          "as": "ld",
          "cond": {
            "$in": [
              "8534sfjog904395",
              "$$ld.v"
            ]
          }
        }
      }
    }
  },
  {
    "$set": {
      "linked_data": {
        "$arrayToObject": "$linked_data"
      }
    }
  },
  {
    $match: {
      linked_data: {
        $ne: {}
      }
    }
  }
])

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answered Feb 3, 2023 at 16:35

ray

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2 Comments

Prity Priya Over a year ago

can't we acheive this without aggregate? by using find ?

ray Over a year ago

@PrityPriya unlikely. You probably will end up getting the raw document(i.e. without array entries filtered). And that likely will impact the readability much as it packs all the code together.

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