Question

由于我是MongoDB的新蜜蜂，因此难以在集合中执行联接。我需要加入特定ID的两个集合。实际上我正在使用模型来实现数据库目的。

Collection 1

{

   "id" : "1",

   "user_id" : "101",

   "job_id" : "j1001"

}

{

   "id" : "2",

   "user_id" : "101",

   "job_id" : "j1002"

}

{

   "id" : "3",

   "user_id" : "101",

   "job_id" : "j1003"

}

收集2

{

   "id" : "1",

   "job_id" : "j1001",

   "name" : "Software engineer",

}

{

   "id" : "2",

   "job_id" : "j1002",

   "name" : "Project manager"

}

{

   "id" : "3",

   "job_id" : "j1003",

   "name" : "FullStack Developer"

}

我想检索collection1中user_id为{1}}的collection1中的所有名称

预期结果将是这样的

非常感谢任何帮助。在此先感谢！

Answer 1

您可以将$lookup阶段与MongoDB的aggregate框架一起使用。

的语法

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

实施例

db.collection1.aggregate([
   {
     $lookup:
       {
         from: "collection2",
         localField: "id1",
         foreignField: "reference id which will be same as id1",
         as: "Array_Docs"
       }
  }
])

如何使用MongoDB和NodeJS执行特定ID的连接

1 个答案: