如何仅在MongoDB聚合中获得数组的前3个值

发布于 2025-02-01 00:49:35 字数 621 浏览 3 评论 0原文

我有一个收藏

"_id": {
    "$oid": "f3187b40cacac21f88c60"
  },
  "recipeId": "3da8f8ddfa600294b278d",
  "dish": "abc",
  
  "Profile": {
    "Tag": [
      {
        "Tag": "X",
        "ratios": 5.9751602852
      },
      {
        "Tag": "Y",
        "ratios": 53.9308283909
      },
      {
        "Tag": "Z",
        "ratios": 12.3244466278
      },
      {
        "Tag": "A",
        "ratios": 13.1145449121
      },
      {
        "Tag": "B",
        "ratios": 1.3848693181
      },
      {
        "Tag": "C",
        "ratios": 1.2996209903
      }

的集合中的收藏，我想要配方，菜肴和top3标签及其比例。

原文

I have a collection which look like this

"_id": {
    "$oid": "f3187b40cacac21f88c60"
  },
  "recipeId": "3da8f8ddfa600294b278d",
  "dish": "abc",
  
  "Profile": {
    "Tag": [
      {
        "Tag": "X",
        "ratios": 5.9751602852
      },
      {
        "Tag": "Y",
        "ratios": 53.9308283909
      },
      {
        "Tag": "Z",
        "ratios": 12.3244466278
      },
      {
        "Tag": "A",
        "ratios": 13.1145449121
      },
      {
        "Tag": "B",
        "ratios": 1.3848693181
      },
      {
        "Tag": "C",
        "ratios": 1.2996209903
      }

In the output of aggregation I want recipeId,dish and top3 tags along with its ratios.I am trying to create a table of recipeId , dish , tags and ratios in Redash.

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深空失忆 2025-02-08 00:49:35

查询

$ sortArray在mongodb 5.2中添加了
波纹管与Undind一起使用，因为您可能没有5.2版本的
放松并进行排序，然后返回，最后仅使用$ slice

playmongo

aggregate(
[{"$unwind": "$Profile.Tag"}, 
 {"$sort": {"Profile.Tag.ratios": -1}},
 {"$group": 
   {"_id": "$_id",
    "recipeId": {"$first": "$recipeId"},
    "dish": {"$first": "$dish"},
    "Tag": {"$push": "$Profile.Tag"}}},
 {"$set": {"Profile": {"Tag": {"$slice": ["$Tag", 3]}},
  "Tag": "$REMOVE"}}])

Query

$sortArray is added in MongoDB 5.2
the bellow works with unwind because probably you dont have the 5.2 version
unwind and sort, group back, and finally take the first 3 only with $slice

Playmongo

aggregate(
[{"$unwind": "$Profile.Tag"}, 
 {"$sort": {"Profile.Tag.ratios": -1}},
 {"$group": 
   {"_id": "$_id",
    "recipeId": {"$first": "$recipeId"},
    "dish": {"$first": "$dish"},
    "Tag": {"$push": "$Profile.Tag"}}},
 {"$set": {"Profile": {"Tag": {"$slice": ["$Tag", 3]}},
  "Tag": "$REMOVE"}}])

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