删除嵌套组中的重复项答案

【问题标题】：Remove duplicate in nested group删除嵌套组中的重复项
【发布时间】：2020-06-26 03:06:53
【问题描述】：

我必须删除与 JSON 中嵌套数组和对象中的父元素具有相同 LocateId 的元素（我正在使用 MongoDB）：

{
 "mainLocation": {
                  "locateId": {"$numberInt": "111111"},
                  "LocateName": "Indonesia",
                  "subLocation": [{
                                "locateId": {"$numberLong": "2222222222"}, *//this the refference for Child location*
                                "LocateName": "Jakarta Pusat",
                                "childLocation": [{
                                                   "locateId": {"$numberLong": "2222222222"},
                                                   *//if the LocateId is same with Sublocation.LocateId will removed*
                                                   "LocateName": "Jakarta Pusat",
                                                 },{
                                                   "locateId": {"$numberLong": "3333333333"},
                                                   "LocateName": "Jakarta Barat",
                                                 }]
                                 },{
                                "locateId": {"$numberLong": "1234123412"},
                                "LocateName": "Bandung",
                                "childLocation": []
                                 }]
                 }
}

而我的预期是：

{
 "mainLocation": {
                  "locateId": {"$numberInt": "111111"},
                  "LocateName": "Indonesia",
                  "subLocation": [{
                                "locateId": {"$numberLong": "2222222222"},
                                "LocateName": "Jakarta Pusat",
                                "childLocation": [{
                                                   "locateId": {"$numberLong": "3333333333"},
                                                   "LocateName": "Jakarta Barat",
                                                 }] *//the element with same Id has been removed*
                                 },{
                                "locateId": {"$numberLong": "1234123412"},
                                "LocateName": "Bandung",
                                "childLocation": []
                                 }]
                 }
}

我尝试了简单的功能，至少可以按我预期的顺序显示

db.pages.aggregate(
    [{ 
            "$group" : {
                LocatediId: "$mainLocation.LocatediId",
                subLocation : {
                        "$group" : { 
                        LocatediId: "$mainLocation.subLocation.LocatediId",
                        Locatedname: "$mainLocation.subLocation.Locatedname"
                        }}
        }}
    ]);

所以我可以将结果导出到 JSON 文件。

【问题讨论】：

您的查询是什么？
您可以通过$filter 完成此操作
请添加您尝试过的一些功能。还结帐行为准则
其实我不知道.. 只是尝试从另一个代码传递.. 并替换变量.. 我还没有找到那个嵌套组.. 我尝试嵌套组但那也是错误......

标签： mongodb mongoose aggregate robo3t studio3t

【解决方案1】：

试试这个：

db.collection.aggregate([
   {
      $set: {
         "mainLocation.subLocation": {
            $map: {
               input: "$mainLocation.subLocation",
               as: "subLocation",
               in: {
                  $mergeObjects: [
                     "$$subLocation",
                     {
                        childLocation: {
                           $filter: {
                              input: "$$subLocation.childLocation",
                              cond: { $ne: ["$$this.locateId", "$$subLocation.locateId"] }
                           }
                        }
                     }
                  ]
               }
            }
         }
      }
   }
])

Mongo playground

【讨论】：

谢谢..我不知道它可能很复杂..它节省了很多时间和精力