MongoDB Aggregate-将文档数组中的某些项分组

Question

我对MongoDB 很陌生

拥有类似的文档

"_id":0001
"Name": "John"
"Contacts": [
{
"Person" : [
{
"User" : {
"_id" : ObjectId("5836b916885383034437d230"),
"Name": "Name1",
"Age" : 25,             
}
},
{
"User" : {
"_id" : ObjectId("2836b916885383034437d230"),
"Name": "Name2",
"Age" : 30,             
}
},
{
"User" : {
"_id" : ObjectId("1835b916885383034437d230"),
"Name": "Name3",
"Age" : 31,             
}
},
}

哪种方式是获得年龄大于或等于30岁的联系人信息的最佳输出？

输出应该是：

{_id: "John", "ContactName":"Name2", "Age":30  }
{_id: "John", "ContactName":"Name3", "Age":31  }

聚合是最好的方法吗？还是可以使用简单的"；查找"；陈述

Answer 1

• $match
• $unwind
• $unwind
• $match
• $project

db.collection.aggregate([
{
"$match": {
"Contacts.Person.User.Age": {
"$gte": 30
}
}
},
{
"$unwind": "$Contacts"
},
{
"$unwind": "$Contacts.Person"
},
{
"$match": {
"Contacts.Person.User.Age": {
"$gte": 30
}
}
},
{
"$project": {
"_id": "$Name",
"ContactName": "$Contacts.Person.User.Name",
"Age": "$Contacts.Person.User.Age"
}
}
])

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