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Mongodb find different values from arrays

I’m using MongoDb version 5.0.6.

I have this structure:

{
  "_id": ObjectId("60c7180d5ef87b4de490c56d"),
  "data": {
    "user": [
      {"country": "Netherlands", "originalCountry": "Denmark"},
      {"country": "France", "originalCountry": "Denmark"},
    ]
  },
"_id": ObjectId("60c7180d5ef87b4de490c56d"),
  "data": {
    "user": [
      {"country": "ITALIE", "originalCountry": "ITALIE"},
      {"country": "France", "originalCountry": "France"},
    ]
  }
},
"_id": ObjectId("60c7180d5ef87b4de490c56d"),
  "data": {
    "user": [
      {"country": "UK", "originalCountry": "CANADA"},
      {"country": "France", "originalCountry": "France"},
    ]
  }
}

I wish to find only the documents that have country equal to supplierCountryin this case:

"_id": ObjectId("60c7180d5ef87b4de490c56d"),
  "data": {
    "user": [
      {"country": "ITALIE", "originalCountry": "ITALIE"},
      {"country": "France", "originalCountry": "France"},
    ]
  }
}

I have tried with this query

db.collection.find({
  "data.user": {
    $elemMatch: {
      "country": {
        $ne: "$data.user.originalCountry"
      }
    }
  }
})

but the result is not right.

Tags:

2

Answers


  1. 0

    By using $map, you can project the data.user array to an array of boolean by comparing the 2 country fields. Then, use $allElementsTrue to find documents that have all array entries true. (i.e. all array entries are having same country)

    db.collection.find({
  "$expr": {
    "$allElementsTrue": {
      "$map": {
        "input": "$data.user",
        "as": "u",
        "in": {
          $eq: [
            "$$u.country",
            "$$u.originalCountry"
          ]
        }
      }
    }
  }
})

    Mongo Playground

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  2. 0

    You can use aggregation. This will compare the 2 values country and originalCountry in the same user object array and return those documents

    db.collection.aggregate([
  {
    $match: {
      $expr: {
        $eq: [
          "$data.user.country",
          "$data.user.originalCountry"
        ]
      }
    }
  }
])

    Mongo Playground: https://mongoplayground.net/p/OhJXK7CC3HX

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