MongoDB $查找在另一个表格中，带有匹配字段作为数组

发布于 2025-01-24 16:51:31 字数 1579 浏览 0 评论 0 原文

我试图返回其他集合中的数组中存在真正的基于错误的值。

假设我的活动收集如下。

{"_id":{"$oid":"626aa83ca3d690ffe4a40103"},"name":"event1","title":"Event 1"}
{"_id":{"$oid":"626aa83ca3d690ffe4a40104"},"name":"event2","title":"Event 2"}
{"_id":{"$oid":"626aa83ca3d690ffe4a40105"},"name":"event3","title":"Event 3"}

我的用户集合如下：

{"_id":{"$oid":"62149d30950b000a31448eb3"},"userName":"[email protected]","commentDictionary":"{}","__v":0,"createdAt":{"$date":"2022-02-22T08:22:08.161Z"},"updatedAt":{"$date":"2022-04-27T07:11:58.999Z"},"passwordResetLinkExpiryDate":{"$date":"2022-03-22T16:40:15.356Z"},"_eventIds":[{"$oid":"626aa83ca3d690ffe4a40103"},{"$oid":"626aa83ca3d690ffe4a40105"}]}

取决于 _Eventids 在用户集合中的匹配值，我正在寻找如下的输出。这也是在用户名中具有

{"_id":{"$oid":"626aa83ca3d690ffe4a40103"},"name":"event1","title":"Event 1", attended: true}
{"_id":{"$oid":"626aa83ca3d690ffe4a40104"},"name":"event2","title":"Event 2", attended: false}
{"_id":{"$oid":"626aa83ca3d690ffe4a40105"},"name":"event3","title":"Event 3", attended: true}

我正在尝试使用$查找，但是它需要一个匹配的密钥，但就我而言，它是数组。因此无法为此删除逻辑。

原文

I am trying to return true false based value exists in array in other collection.

Let's say my Event collection is as following.

{"_id":{"$oid":"626aa83ca3d690ffe4a40103"},"name":"event1","title":"Event 1"}
{"_id":{"$oid":"626aa83ca3d690ffe4a40104"},"name":"event2","title":"Event 2"}
{"_id":{"$oid":"626aa83ca3d690ffe4a40105"},"name":"event3","title":"Event 3"}

My User Collection is as following:

{"_id":{"$oid":"62149d30950b000a31448eb3"},"userName":"[email protected]","commentDictionary":"{}","__v":0,"createdAt":{"$date":"2022-02-22T08:22:08.161Z"},"updatedAt":{"$date":"2022-04-27T07:11:58.999Z"},"passwordResetLinkExpiryDate":{"$date":"2022-03-22T16:40:15.356Z"},"_eventIds":[{"$oid":"626aa83ca3d690ffe4a40103"},{"$oid":"626aa83ca3d690ffe4a40105"}]}

depending on matching values in _eventIds in User Collection, I am looking for output as following. And that is also in userName having value as [email protected]

{"_id":{"$oid":"626aa83ca3d690ffe4a40103"},"name":"event1","title":"Event 1", attended: true}
{"_id":{"$oid":"626aa83ca3d690ffe4a40104"},"name":"event2","title":"Event 2", attended: false}
{"_id":{"$oid":"626aa83ca3d690ffe4a40105"},"name":"event3","title":"Event 3", attended: true}

I was trying with $lookup but it needs one matching key, but in my case it is Array. So unable to figure logic for this.

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

誰認得朕 2025-01-31 16:51:31

查询

查找在单个值/数组上工作，并且如果数组包含此值，
而不是进行所有将慢的查找，更多的内存等， $ limit 1 is使用的，因为我们只关心是否找到匹配
，结果是空的=＆gt; ACTENTED = false;否则参加= true

Event.aggregate(
[{"$lookup": 
   {"from": "User",
    "localField": "_id",
    "foreignField": "_eventIds",
    "pipeline": [{"$limit": 1}],
    "as": "attended"}},
 {"$set": 
   {"attended": {"$cond": [{"$eq": ["$attended", []]}, false, true]}}}])

Query

lookup works on single value/array, and matches if the array contains this value
instead of doing all the lookup that will be slower, more memory etc, $limit 1 is used, because we only care if match was found or not
if results are empty => attented = false else attended=true

Playmongo

Event.aggregate(
[{"$lookup": 
   {"from": "User",
    "localField": "_id",
    "foreignField": "_eventIds",
    "pipeline": [{"$limit": 1}],
    "as": "attended"}},
 {"$set": 
   {"attended": {"$cond": [{"$eq": ["$attended", []]}, false, true]}}}])

回复收藏 0 原文

~没有更多了~