获取所有唯一用户的 MongoDB 查询

Question

我目前正在使用 MongoDB 数据库。我的问题是我有很多同名的人，但他们是不同的人，有不同的年龄、出生地等。

文档示例如下：

{
        "_id" : ObjectId("6072fee3145c156c123ce3"),
        "Users" : [
                {
                        "name" : "John Davies",
                        "age" : NumberLong(35),
                        "place_of_birth" : "Cardigan"
                },
                {
                        "name" : "Edward Jones",
                        "age" : "blank",
                        "place_of_birth" : "Liverpool"
                },
                {
                        "name" : "Daniel Rhys",
                        "age" : NumberLong(63),
                        "place_of_birth" : "Cardigan"
                },
                {
                        "name" : " Evan Williams",
                        "age" : NumberLong(61),
                        "place_of_birth" : "Cardigan"
                },
                {
                        "name" : "John Davies ",
                        "age" : NumberLong(21),
                        "place_of_birth" : "Cardigan"
                }
        ]
}
{
        "_id" : ObjectId("6072fee3145c156c321ef6"),
        " Users " : [
                {
                        "name" : "John Davies",
                        "age" : NumberLong(35),
                        "place_of_birth" : "Swansea"
                },
                {
                        "name" : "Edward Jones",
                        "age" : "blank",
                        "place_of_birth" : "Liverpool"
                },
                {
                        "name" : "Daniel Rhys ",
                        "age" : NumberLong(63),
                        "place_of_birth" : "Barry"
                },
                {
                        "name" : "Evan Williams",
                        "age" : NumberLong(61),
                        "place_of_birth" : "Cardigan"
                },
                {
                        "name" : "John Davies",
                        "age" : NumberLong(21),
                        "place_of_birth" : "Cardigan"
                }
        ]
}

所以我的目标是查询这些数据，以便获得所有姓名以及每个唯一人员的年龄和出生地一次。

所以输出应该包含（我只是放入一个表格以更清楚地显示查询结果应该是什么）：

Name	Age	Birth place
John Davies	35	Cardigan
Edward Jones	Blank	Liverpool
Daniel Rhys	63	Cardigan
Evan Williams	61	Cardigan
John Davies	21	Cardigan
Daniel Rhys	63	Barry
John Davies	35	Swansea

非常感谢任何有关最佳方法的建议或指导

Answer 1

• $unwind解构Users数组
• $group by Users 对象
• $replaceRoot 将 Users 对象替换为根

db.collection.aggregate([
  { $unwind: "$Users" },
  { $group: { _id: "$Users" } },
  { $replaceRoot: { newRoot: "$_id" } }
])

Playground

---

第二个选项：$replaceRoot 的替代选项，

• $project 显示必填字段

db.collection.aggregate([
  { $unwind: "$Users" },
  { $group: { _id: "$Users" } },
  {
    $project: {
      _id: 0,
      name: "$_id.name",
      age: "$_id.age",
      place_of_birth: "$_id.place_of_birth"
    }
  }
])

Playground