In MongoDB, is it possible to query a property (individual value) of a document hierarchy only by querying the whole document, or is it possible in parts, with any nesting level?

Question

NoSQL

In MongoDB, is it possible to query a property (individual value) of a document hierarchy only by querying the whole document, or is it possible in parts, with any level of nesting?

Answer 1

Да, можно.
При записях в базе вида:

{
  "_id": ObjectId("530824b95f44eac1068b45c8"), 
  "accs": {
    "boss": {
      "name": "Stefan",
      "roles": ["admin", "ceo"]
    }
  },
  "ingener": {
    "name": "Jhon",
    "roles": ["user", "staff"]
  }
}

Можно сделать запрос db.collection.find({},{ "accs.boss.roles": {$slice: -1} }) и получить:

{ 
  "accs": {
    "boss": {
      "roles": ["ceo"]
    }
  }
}