Mongodb query sub document $gt [duplicate] - mongodb

Question

This question already has answers here:
Retrieve only the queried element in an object array in MongoDB collection
(18 answers)
Closed 3 years ago.
I had searched other posts, but what seems to work fine just couldn't work here. I need your advice.
Here is what my document looks like in the database, just one document with a series of tag in it.
I need to just query, the restaurant type which has counter greater than 0, (so the end result will exclude any type with counter 0)
My schema
const tagsSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
details: {
restaurantTypeId: mongoose.Schema.Types.ObjectId,
restaurantTypes: [{
_id: mongoose.Schema.Types.ObjectId,
name: String,
counter: Number,
}],
foodTypeId: mongoose.Schema.Types.ObjectId,
foodTypes: [{
_id: mongoose.Schema.Types.ObjectId,
name: String,
counter: Number,
}]
}
});
I have tried
tags.find({
'details.restaurantTypes.counter': {
$gt: 0
}
}, (err, data) => {
if (err) {
res.send(err);
}
res.json(data);
});
and I got
[
{
"details": {
"restaurantTypeId": "5c01fb57497a896d50f49877",
"restaurantTypes": [
{
"_id": "5c01fb57497a896d50f49879",
"name": "Asian",
"counter": 1
},
{
"_id": "5c01fb57497a896d50f4987a",
"name": "Bakery",
"counter": 0
},
{
"_id": "5c01fb57497a896d50f4987b",
"name": "Barbecue",
"counter": 0
},
{
"_id": "5c01fb57497a896d50f4987c",
"name": "Bars & Pubs",
"counter": 0
},
{
"_id": "5c01fb57497a896d50f4987d",
"name": "Bistro",
"counter": 0
},
and
tags.find({
'details.restaurantTypes.counter': {
$gte: 1
}
}, (err, data) => {
if (err) {
res.send(err);
}
res.json(data);
});
which give me the same result

Answer 1

You can use aggregation pipeline to filter the restaurantTypes
$match - filter the restaurant
$addFields - to overwrite restaurantTypes and $filter the restaurant types by counter
aggregated pipeline
db.res.aggregate([
{$match: {"_id" : ObjectId("5c2187be640edfe094a3b946")}},
{$addFields:{"restaurantTypes" : {$filter : {input : "$restaurantTypes", as : "t", cond : {$ne : ["$$t.counter",0]}}}}}
])

Answer 2

Okay, I found the answer, inspired by Saravana.
here is the answer using aggregate and filter.
tags.aggregate([{
$match: {
"_id": mongoose.Types.ObjectId(id)
}
},
{
$project: {
"details.restaurantTypes": {
$filter: {
input: "$details.restaurantTypes",
as: "resType",
cond: {
$ne: ["$$resType.counter", 0]
}
}
}
}
}
]
this will give me the result
[
{
"_id": "5c01fb57497a896d50f49876",
"details": {
"restaurantTypes": [
{
"_id": "5c01fb57497a896d50f49879",
"name": "Asian",
"counter": 1
},
{
"_id": "5c01fb57497a896d50f498a6",
"name": "Thai",
"counter": 1
},
{
"_id": "5c01fb57497a896d50f498a8",
"name": "Western",
"counter": 1
}
]
}
}
]