How to get subdocument without root document?-CodePudding

I have this json file

{
  "_id": "1",
  "name": "sanggiyo",
  "gender": "Male",
  "children": [
    {
      "name": "tono",
      "gender": "Male",
      "children": [],
      "_id": "2"
    },
    {
      "name": "rin",
      "gender": "Female",
      "children": [],
      "_id": "3"
    }
  ],
  "createdAt": "2022-04-17T11:14:00.648Z",
  "updatedAt": "2022-04-17T11:14:16.277Z",
  "__v": 0
}

I want to get children._id using

  Person.find( {$or: [ { "_id" : id }, { "children._id" : ObjectId(id) } ]} )

if I use id of 1, I should get all document. but if I use id of 2, I should only get that children object without id 1, is there a way to do it?

CodePudding user response：

You can try doing with aggregation framework, but much more readable and maintainable way to do that is in the code after the mongo query returned similar to that:

const persons = await Person.find({$or: [ { "_id" : id }, { "children._id" : ObjectId(id) } ]});

const result = persons.flatMap(p => [p, ...p.children]).find(p => p._id === id);