Question

我在第二级数组中有重复项。

在第二级数组元素中，除_id之外，所有列都包含相同的数据。在某些情况下_id也是一样的。

请建议如何通过保留一个元素来从第二级数组中删除重复项。

从下面的示例中，我们可以将AssessmentName视为Bhra数组中的唯一字段。

Mongo版本：3.2.8 例如：

{
    "_id" : ObjectId("592415c434810eeb63afe029"),
    "Encounter" : [ 
        {
            "_id" : ObjectId("5846c6361489b54e402d76f6"),
            "Bhra" : [ 
                {
                    "_id" : "15445853419048538e0ba2cd",
                    "AssessmentId" : 1,
                    "AssessmentName" : "Major Depressive Episode",
                    "AssessmentOrder" : 1,
                    "IsContinue" : true,
                    "IsNotAssessed" : false,
                    "TotalScore" : 9,
                    "DepressionSeverity" : "Mild depression",
                    "AssessmentResult" : "Negative",
                    "Notes" : ""
                }, 
                {
                    "_id" : "15445853419048538e0ba2aa",
                    "AssessmentId" : 1,
                    "AssessmentName" : "Major Depressive Episode",
                    "AssessmentOrder" : 1,
                    "IsContinue" : true,
                    "IsNotAssessed" : false,
                    "TotalScore" : 9,
                    "DepressionSeverity" : "Mild depression",
                    "AssessmentResult" : "Negative",
                    "Notes" : ""
                }, 
                {
                    "_id" : "15445853419048538e0ba2aa",
                    "AssessmentId" : 1,
                    "AssessmentName" : "Major Depressive Episode",
                    "AssessmentOrder" : 1,
                    "IsContinue" : true,
                    "IsNotAssessed" : false,
                    "TotalScore" : 9,
                    "DepressionSeverity" : "Mild depression",
                    "AssessmentResult" : "Negative",
                    "Notes" : ""
                }
            ]
        }
    ]
}

输出应如下所示。

{
"_id" : ObjectId("592415c434810eeb63afe029"),
    "Encounter" : [ 
        {
            "_id" : ObjectId("5846c6361489b54e402d76f6"),
            "Bhra" : [ 
                {
                    "_id" : "15445853419048538e0ba2cd",// any _id is fine
                    "AssessmentId" : 1,
                    "AssessmentName" : "Major Depressive Episode",
                    "AssessmentOrder" : 1,
                    "IsContinue" : true,
                    "IsNotAssessed" : false,
                    "TotalScore" : 9,
                    "DepressionSeverity" : "Mild depression",
                    "AssessmentResult" : "Negative",
                    "Notes" : ""
                }
            ]
        }
    ]
}

谢谢，饶

Answer 1

您可以使用聚合。首先，您需要$unwind次数据才能达到2级数组，然后使用$group仅包含数组中的不同项。最后，$project为必需的json格式。

db.your_collection.aggregate([
    {"$unwind":"$Encounter"},
    {"$unwind":"$Encounter.Bhra"},
    {"$group":{
            _id: {
                _id:"$_id",
                "Encounter_id":"$Encounter._id", 
                "Encounter_Bhra_AssessmentId":"$Encounter.Bhra.AssessmentId",
                "Encounter_Bhra_AssessmentName":"$Encounter.Bhra.AssessmentName",
                "Encounter_Bhra_AssessmentOrder":"$Encounter.Bhra.AssessmentOrder",
                "Encounter_Bhra_IsContinue":"$Encounter.Bhra.IsContinue",
                "Encounter_Bhra_IsNotAssessed":"$Encounter.Bhra.IsNotAssessed",
                "Encounter_Bhra_TotalScore":"$Encounter.Bhra.TotalScore",
                "Encounter_Bhra_DepressionSeverity":"$Encounter.Bhra.DepressionSeverity",
                "Encounter_Bhra_AssessmentResult":"$Encounter.Bhra.AssessmentResult",
                "Encounter_Bhra_Notes":"$Encounter.Bhra.Notes"
                },
            "Encounter_Bhra_id":{"$min":"$Encounter.Bhra._id"}
        }
    },
    {"$project":{
            _id:"$_id._id",
            Encounter : {
                _id:"$_id.Encounter_id",
                Bhra : {
                    _id : "$Encounter_Bhra_id",
                    AssessmentId : "$_id.Encounter_Bhra_AssessmentId",
                    AssessmentName : "$_id.Encounter_Bhra_AssessmentName",
                    AssessmentOrder : "$_id.Encounter_Bhra_AssessmentOrder",
                    IsContinue : "$_id.Encounter_Bhra_IsContinue",
                    IsNotAssessed : "$_id.Encounter_Bhra_IsNotAssessed",
                    TotalScore : "$_id.Encounter_Bhra_TotalScore",
                    DepressionSeverity : "$_id.Encounter_Bhra_DepressionSeverity",
                    AssessmentResult : "$_id.Encounter_Bhra_AssessmentResult",
                    Notes : "$_id.Encounter_Bhra_Notes"
                }
            }
        }    
    },
    {$out: "your_new_coll_name"}
])

输出：

{
    "_id" : ObjectId("592415c434810eeb63afe029"),
    "Encounter" : {
        "_id" : ObjectId("5846c6361489b54e402d76f6"),
        "Bhra" : {
            "_id" : "15445853419048538e0ba2aa",
            "AssessmentId" : 1,
            "AssessmentName" : "Major Depressive Episode",
            "AssessmentOrder" : 1,
            "IsContinue" : true,
            "IsNotAssessed" : false,
            "TotalScore" : 9,
            "DepressionSeverity" : "Mild depression",
            "AssessmentResult" : "Negative",
            "Notes" : ""
        }
    }
}

如何从Mongo DB中的第二级数组中删除重复项

1 个答案: