Question 220523 in Mongodb Question posted in
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MongoDb, Convert UUID to string, in projection

I’m looking for a solution to convert a UUID to a string using projection. I’ve tried many different ways, but none of them are working.

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The stranger thing is that Metabase displays the ID correctly, but I cannot manipulate this data because it’s not in string format.

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Have you any idea ?

Thanks a lot

Benjamin

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2

Answers


  1. Chosen as BEST ANSWER
    0

    @rickhg12hs

    Thank you a lot, your answer help me !

    But in my case my Id was BinData 3

    {
  "_id": BinData(3, "OyQRAeK7QlWMr0E2xWapYg==")
}

    I refactor your answer as follow :

    db.collection.aggregate([
  {
    "$project": {
      "_idUUIDstr": {
        "$function": {
          "body": "function convert(s){let t=s.hex();var r=t.substr(6,2)+t.substr(4,2)+t.substr(2,2)+t.substr(0,2),u=t.substr(10,2)+t.substr(8,2),b=t.substr(14,2)+t.substr(12,2),e=t.substr(16,16);return t=r+u+b+e,t.substr(0,8)+'-'+t.substr(8,4)+'-'+t.substr(12,4)+'-'+t.substr(16,4)+'-'+t.substr(20,12)}",
          "args": [
            "$_id"
          ],
          "lang": "js"
        }
      }
    }
  }
])

    and is work perfectly

    RESULT

    [
  {
    "_id": BinData(3, "OyQRAeK7QlWMr0E2xWapYg=="),
    "_idUUIDstr": "0111243b-bbe2-5542-8caf-4136c566a962"
  }
]

    https://mongoplayground.net/p/qf7e5d2aA41


  2. 0

    I hope there is a better answer as I consider this very fragile since it depends on JavaScript execution being enabled on the MongoDB server and a fixed toString representation of BinData UUID. Until there is something better, perhaps this is good enough.

    db.collection.aggregate([
  {
    "$project": {
      "_idUUIDstr": {
        "$function": {
          "body": "function(x) {return x.toString().slice(6,-2)}",
          "args": ["$_id"],
          "lang": "js"
        }
      }
    }
  }
])

    Example document:

    {
  "_id": BinData(4, "OyQRAeK7QlWMr0E2xWapYg==")
}

    Example output:

    {
  "_id": BinData(4, "OyQRAeK7QlWMr0E2xWapYg=="),
  "_idUUIDstr": "3b241101-e2bb-4255-8caf-4136c566a962"
}

    Try it on mongoplayground.net.

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