How can i access N th level of Sub Document in MongoDB - mongodb

Question

{
"_id" : ObjectId("5b4d815ad85250f4e502d142"),
"company_Name" : "Rishabh Instruments",
"spaces" : [
{
"_id" : "11",
"name" : "Trishala",
"spaces" : [
{
"_id" : "111",
"name" : "ESL"
},
{
"_id" : "112",
"name" : "IS"
}
]
},
{
"_id" : "12",
"name" : "Riddhi",
"spaces" : [
{}
]
},
{
"name" : "XYZ",
"spaces" : [
{}
]
}
]
}
This is my Document structure in Mongo DB and it may have the sub documents upto N th level so for now I want to access the document named with ESL and IS. so how can i do that i am able to go upto 2nd level with below query so
db.space.aggregate([
{$match: {company_Name: 'Rishabh Instruments'}},
{$unwind: '$spaces'},
{$match: {'spaces.name': 'Trishala'}}
// {$unwind: '$spaces'},
// {$match: {'spaces.name': 'ESL'}}
])
but if i uncomment those two lines then it doesn't return any thing
so can anyone guide me or give any hint.

Answer 1

I tried the below solution and its working as expected i can go to N th level by chaining the key as in my case key is spaces
db.space.aggregate([
{$match: {company_Name: 'Rishabh Instruments'}},
{$unwind: '$spaces'},
{$match: {'spaces.name': 'Trishala'}},
{$unwind: '$spaces.spaces'},
{$match: {'spaces.spaces.name': 'ESL'}}
])

Answer 2

Try this aggregate query with projection to match the sample output you had provided :
db.space.aggregate([
{$match: {company_Name: 'Rishabh Instruments'}},
{$unwind: '$spaces'},
{$match: {'spaces.name': 'Trishala'}},
{$unwind: '$spaces.spaces'},
{$match: {$or : [{'spaces.spaces.name': 'ESL'},{'spaces.spaces.name': 'IS'}]}},
{$project : {_id : 0, _id :'$spaces.spaces._id', name:'$spaces.spaces.name'}}
])
Output :
{ "_id" : "111", "name" : "ESL" }
{ "_id" : "112", "name" : "IS" }