Find or forEach Inside Aggregate MongoDB - mongodb

Question

Let's say I have two collection in my database call rumahsakit.
First collection called dim_dokter:
[{
"_id": ObjectId("58b22c79e8c1c52bf3fad997"),
"nama_dokter": "Dr. Basuki Hamzah",
"spesialisasi": "Spesialis Farmakologi Klinik",
"alamat": " Jalan Lingkar Ring Road Utara, Yogyakarta "
}, {
"_id": ObjectId("58b22c79e8c1c52bf3fad998"),
"nama_dokter": "Dr. Danie Nukman",
"spesialisasi": "Spesialis Anak",
"alamat": " Jalan Sudirman, Yogyakarta "
}, {
"_id": ObjectId("58b22c79e8c1c52bf3fad999"),
"nama_dokter": "Dr. Bambang Kurnia",
"spesialisasi": "Spesialis Mikrobiologi Klinik",
"alamat": " Jalan Ahmad Yani, Yogyakarta "
}]
Second collection called fact_perawatan:
[{
"_id": ObjectId("58b22d13e8c1c52bf3fad99a"),
"nama_pasien": "Clark",
"detail_perawatan": [{
"id_dokter": ObjectId("58b22c79e8c1c52bf3fad997"),
"jumlah_obat": 1
}, {
"id_dokter": ObjectId("58b22c79e8c1c52bf3fad998"),
"jumlah_obat": 1
}]
}]
Collection fact_perawatan have the id_dokter that is actually point to the dim_dokter._id . I want to do aggregation to show this data in fact_perawatan collection but instead showing just the id_dokter, I want to use nama_dokter from dim_dokter.
This is my code so far:
db.fact_perawatan.aggregate([
{
$match:
{
'_id': db.fact_perawatan.find({"_id" : ObjectId("58b22d13e8c1c52bf3fad99a")})[0]._id
}
},
{
$project:
{
nama_pasien: db.fact_perawatan.find({"_id": ObjectId("58b22d13e8c1c52bf3fad99a")})[0].nama_pasien,
perawatan: [
{
dokter: db.dim_dokter.find({"_id" : db.fact_perawatan.find({"_id": ObjectId("58b22d13e8c1c52bf3fad99a")})[0].detail_perawatan[0].id_dokter})[0].nama_dokter,
},
]
}
}
])
result:
{ "_id" : ObjectId("58b22d13e8c1c52bf3fad99a"), "nama_pasien" : "Clark", "perawatan" : [ { "dokter" : "Dr. Basuki Hamzah" } ] }
Those code can get the nama_dokter from dim_dokter, but only one data. In my case, the data can be up to 5. do the detail_perawatan[0] to [5] is not solution.
So, this code:
db.dim_dokter.find({"_id" : db.fact_perawatan.find({"_id": ObjectId("58b22d13e8c1c52bf3fad99a")})[0].detail_perawatan[0].id_dokter})[0].nama_dokter,
How make the code above to loop as many as the data in there ? so I can get all the data.
Thanks

Answer 1

You can use a $lookup to left join with dim_dokter following by a $group to regroup your data in perawatan field :
db.fact_perawatan.aggregate([{
$match: {
'_id': ObjectId("58b22d13e8c1c52bf3fad99a")
}
}, {
$unwind: "$detail_perawatan"
}, {
$lookup: {
from: "dim_dokter",
localField: "detail_perawatan.id_dokter",
foreignField: "_id",
as: "dim_dokter"
}
}, {
$unwind: "$dim_dokter"
}, {
$group: {
_id: "$_id",
nama_pasien: {
$first: "$nama_pasien"
},
perawatan: {
$push: {
"dokter": "$dim_dokter.nama_dokter"
}
}
}
}])
The $unwind is used to deconstruct the array field detail_perawatan to be able to $lookup afterwards