1

I have a very complex json document in mongo like below:

{
    "Category": [
        {
            "Name" : "",
            "Description": "",
            "SubCategory" : [
                {
                    "Name": "",
                    "Description": "",
                    "Services": [
                        {"ServiceA": [
                            {
                                "Name": "",
                                "Description": "",
                                "CodeA": "1234"
                            }
                        ]},
                        {"ServiceB" : [
                            {
                                "Name": "",
                                "Description": "",
                                "CodeBC": "ABCD",
                                "Key": ""
                            }
                        ]},
                        {"ServiceC": [
                            {
                                "Name": "",
                                "Description": "",
                                "CodeBC": "ABCD",
                                "Section": [
                                    {
                                        "Name": "",
                                        "Description": ""
                                    }
                                ]
                            }
                        ]}
                    ]
                }
            ]
        }
    ]
}

Now I want to retrieve the same document from Mongo but I want it to match only those objects inside ServiceA having CodeA = "1234" and those inside ServiceB and ServiceC having CodeBC = "ABCD". I want it to remove all other objects inside ServiceA, ServiceB and ServiceC not matching the above condition and retrieve the document while maintaining the structure as it is.

Please Note : In the above example I just showed arrays containing single objects and fields that I want to retrieve but in real case it's very complex.

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  • Is there something in the provided answer that you believe does not address your question? If so then please comment on the answer to clarify what exactly needs to be addressed that has not. If it does in fact answer the question you asked then please note to Accept your Answers to the questions you ask Commented Jan 19, 2021 at 5:11

1 Answer 1

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2

Try nested $map to iterate loop in your nested arrays, $mergeObjects to merge current object and new that we want to filter,

At the end in Services array filter documents on the base of condition in $filter, if filtered is null then that field will be removed using $ifNull

db.collection.aggregate([
  {
    $set: {
      Category: {
        $map: {
          input: "$Category",
          as: "c",
          in: {
            $mergeObjects: [
              "$$c",
              {
                SubCategory: {
                  $map: {
                    input: "$$c.SubCategory",
                    as: "sc",
                    in: {
                      $mergeObjects: [
                        "$$sc",
                        {
                          Services: {
                            $map: {
                              input: "$$sc.Services",
                              as: "s",
                              in: {
                                $mergeObjects: [
                                  "$$s",
                                  {
                                    ServiceA: {
                                      $ifNull: [
                                        {
                                          $filter: {
                                            input: "$$s.ServiceA",
                                            cond: { $eq: ["$$this.CodeA", "1234"] }
                                          }
                                        },
                                        "$$REMOVE"
                                      ]
                                    },
                                    ServiceB: {
                                      $ifNull: [
                                        {
                                          $filter: {
                                            input: "$$s.ServiceB",
                                            cond: { $eq: ["$$this.CodeBC", "ABCD"] }
                                          }
                                        },
                                        "$$REMOVE"
                                      ]
                                    },
                                    ServiceC: {
                                      $ifNull: [
                                        {
                                          $filter: {
                                            input: "$$s.ServiceC",
                                            cond: { $eq: ["$$this.CodeBC", "ABCD"] }
                                          }
                                        },
                                        "$$REMOVE"
                                      ]
                                    }
                                  }
                                ]
                              }
                            }
                          }
                        }
                      ]
                    }
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
])

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