带有子查询的 MongoDB $in

Question

我下面有这组合集..

团队集合:

{
   total: 3
   data: [
      {
         "_id": "t1",
         "name": "white horse",
         "leader_id": "L1"
         "teamScore": 12,
         "active": 1
      },
      {
         "_id": "t2",
         "name": "green hornets",
         "leader_id": "L2",
         "teamScore": 9,
         "active": 1
      },
      {
         "_id": "t3",
         "name": "pink flaminggo",
         "leader_id": "L3",
         "teamScore": 22,
         "active": 1
      },
   ]
}

领袖合集:

{
   total: 3
   data: [
      {
         "_id": "L1",
         "name": "John Doe",
         "organization": "Software Development",
         "active": 1
      },
      {
         "_id": "L2",
         "name": "Peter Piper",
         "organization": "Software Development"
         "active": 1
      },
      {
         "_id": "L3",
         "name": "Mary Lamb",
         "organization": "Accounting Department"
         "active": 1
      },
   ]
}

查询应如下所示:SELECT * FROM teams WHERE active = 1 AND leader_id IN (SELECT id FROM leaders WHERE organization = 'Software Development')

我是 mongodb 的新手，我的问题是如何在 mongoDB 聚合框架中转换上面的查询？

Answer 1

您可以使用 $lookup带管道，

• $match 将检查 active 状态
• $lookup 将加入 leaders 集合
  • $match 检查 leader_id 和 organization
• $match 检查领导者是否[] 为空
• $project 删除 leaders 字段

db.teams.aggregate([
  { $match: { active: 1 } },
  {
    $lookup: {
      from: "leaders",
      let: { leader_id: "$leader_id" },
      as: "leaders",
      pipeline: [
        {
          $match: {
            $and: [
              { $expr: { $eq: ["$_id", "$$leader_id"] } },
              { organization: "Software Development" }
            ]
          }
        }
      ]
    }
  },
  { $match: { leaders: { $ne: [] } } },
  { $project: { leaders: 0 } }
])

Playground