How to join deeply nested array? - mongodb

Question

Here is my actual database schema.
company_id is reference object of companies collection and booking_days.consultants.consultant_id is reference object of users collection.
I want to join embedded document with company_id and booking_days.consultants.consultant_id.
{
"_id" : ObjectId("5a7040d664544e1bb877deae"),
"company_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"booking_days" : [
{
"booking_date" : ISODate("2018-01-31T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877deca"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877decc")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877decb")
}
]
},
{
"booking_date" : ISODate("2018-02-01T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec6"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877dec9")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877dec8")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877dec7")
}
]
},
{
"booking_date" : ISODate("2018-02-02T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec4"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877dec5")
}
]
},
],
"__v" : 0
}
I am using below query.
db.getCollection('booking_days').aggregate(
[
{ $match: { company_id:ObjectId("5a6eb43f437e6a0d9e00c92f") } },
{
$lookup: {
localField: "company_id",
from: "companies",
foreignField: "_id",
as: "companies"
},
},
{
$lookup: {
localField: "booking_days.consultants.consultant_id",
from: "users",
foreignField: "_id",
as: "userssss"
},
},
{
$unwind:"$companies"
},
]
)
Actual Output
{
"_id" : ObjectId("5a7040d664544e1bb877deae"),
"company_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"booking_days" : [
{
"booking_date" : ISODate("2018-01-31T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877deca"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877decc")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877decb")
}
]
},
{
"booking_date" : ISODate("2018-02-01T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec6"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877dec9")
},
]
},
],
"__v" : 0,
"companies" : {
"_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"first_name" : "Adrienne Runolfsson",
},
"users" : [
{
"_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"first_name" : "Christ Hamill",
},
{
"_id" : ObjectId("5a6f2854ce7d6938de1dd52e"),
"first_name" : "Miss Dina Kovacek",
},
]
}
Excepted output. consultant data will come in booking_days.consultants array.
{
"_id" : ObjectId("5a7040d664544e1bb877deae"),
"company_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"booking_days" : [
{
"booking_date" : ISODate("2018-01-31T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877deca"),
"consultants" : [
{
"consultant_id" : {
"_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"first_name" : "Christ Hamill",
},
"_id" : ObjectId("5a7040d664544e1bb877decc")
},
{
"consultant_id" : {
"_id" : ObjectId("5a6f2854ce7d6938de1dd52e"),
"first_name" : "Miss Dina Kovacek",
},
"_id" : ObjectId("5a7040d664544e1bb877decb")
}
]
},
{
"booking_date" : ISODate("2018-02-01T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec6"),
"consultants" : [
{
"consultant_id" : {
"_id" : ObjectId("5a6f2854ce7d6938de1dd52e"),
"first_name" : "Miss Dina Kovacek",
},
"_id" : ObjectId("5a7040d664544e1bb877dec9")
},
]
},
],
"__v" : 0,
"companies" : {
"_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"first_name" : "Adrienne Runolfsson",
},
}

Answer 1

As such you have to $unwind the localField when it is an embedded document array expect in some cases where localField is an array of scalar ids.
$unwind twice as consultant array is two levels deep followed by $lookup to get the name and $group to get back the expected output.
db.getCollection('booking_days').aggregate([
{"$match":{"company_id":ObjectId("5a6eb43f437e6a0d9e00c92f")}},
{"$lookup":{"localField":"company_id","from":"companies","foreignField":"_id","as":"companies"}},
{"$unwind":"$companies"},
{"$unwind":"$booking_days"},
{"$unwind":"$consultants"},
{"$lookup":{
"localField":"booking_days.consultants.consultant_id",
"from":"users",
"foreignField":"_id",
"as":"booking_days.consultants.consultant_id"
}},
{"$group":{
"_id":{"_id":"$_id","booking_days_id":"$booking_days._id"},
"company_id":{"$first":"$company_id"},
"booking_date":{"$first":"$booking_days.booking_date"},
"companies":{"$first":"$companies"},
"consultants":{"$push":"$booking_days.consultants"}
}},
{"$group":{
"_id":"$_id._id",
"company_id":{"$first":"$company_id"},
"companies":{"$first":"$companies"},
"booking_days":{
"$push":{
"_id":"$_id.booking_days_id",
"booking_date":"$booking_date",
"consultants":"$consultants"
}
}
}}
])

Answer 2

{"Id": "5b87a4c79a9c3feac943fc6c",
"comments" : [
{
"likes" : [],
"_id" : ObjectId("5b87a4c79a9c3feac943fc6c"),
"comment" : "string",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"commentId" : "7d2a05d1-2026-4a13-a5c1-318ed80d1b38",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
}
]
},
{
"likes" : [],
"_id" : ObjectId("5b87c301c8a07efa2599c29e"),
"comment" : "testing",
"accountId" : "cfd29f53-d73e-480c-9cfa-ea42b4119266",
"commentId" : "0676047b-1712-4f70-89d5-29c1abe03eaf",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
}
]
}
]
}
accountId is in differnt connection
// Expected Out Put
{"Id": "5b87a4c79a9c3feac943fc6c",
"comments" : [
{
"likes" : [],
"_id" : ObjectId("5b87a4c79a9c3feac943fc6c"),
"comment" : "string",
"name" : "apple",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"name" : "apple",
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"name" : "apple",
}
]
},
{
"likes" : [],
"_id" : ObjectId("5b87c301c8a07efa2599c29e"),
"comment" : "testing",
"name" : "ball",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"name" : "apple",
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"name" : "apple", }
]
}
]
}