Mongodb直接获取ObjectId

Question

我有一个 "company" collection 这样的：

{
  "_id" : ObjectId("58c52a26de0bdd9311000004"), 
  "name" : "ed", 
  "projects" : [ ], 
  "__v" : 0, 
  "users" : [
    ObjectId("58c52a36de0bdd9311000007"),
    ObjectId("58c52a54de0bdd931100000a")
  ]
}

我想从用户那里得到一些信息；我是否必须执行一个查询以获取 ObjectID 和另一个对每个用户的查询？

或者有什么方法可以直接从公司查询中获取此信息？

Answer 1

您可以使用查找聚合从用户集合中获取数据，前提是这两个集合都在同一个数据库中。

Performs a left outer join to an unsharded collection in the same database to filter in documents from the “joined” collection for processing. The $lookup stage does an equality match between a field from the input documents with a field from the documents of the “joined” collection.

基本语法：-

{
   $lookup:
     {
       from: <collection to join>,
       localField: <field from the input documents>,
       foreignField: <field from the documents of the "from" collection>,
       as: <output array field>
     }
}

MongoDB lookup

Mongodb直接获取ObjectId

Mongodb direct access to ObjectId

mongodb

objectid