Querying with mongoose/mongoDB on nested document - node.js

Question

I have a car model given as below
{
"_id": "54b8a71843286774060b8bed",
"name": "Car1",
"active": true,
"model": [
{
"name": "Model1",
"active": true,
"_id": "54b8a71843286774060b8bee",
"available": [
{
"Day": "Mon",
"quantity": "6"
},
{
"Day": "Tue",
"quantity": "6"
},
{
"Day": "Wed",
"quantity": "6"
},
{
"Day": "Thurs",
"quantity": "6"
},
{
"Day": "Fri",
"quantity": "0"
}
]
},
{
"name": "Model2",
"active": true,
"_id": "54b8a71843286774060b8bef",
"available": [
{
"Day": "Mon",
"quantity": "6"
},
{
"Day": "Tue",
"quantity": "6"
},
{
"Day": "Wed",
"quantity": "6"
},
{
"Day": "Thurs",
"quantity": "6"
},
{
"Day": "Fri",
"quantity": "6"
}
]
},
{
"name": "Model3",
"active": true,
"_id": "54b8a71843286774060b8beg",
"available": [
{
"Day": "Mon",
"quantity": "6"
},
{
"Day": "Tue",
"quantity": "6"
},
{
"Day": "Wed",
"quantity": "6"
},
{
"Day": "Thurs",
"quantity": "6"
},
{
"Day": "Fri",
"quantity": "0"
}
]
}
]
}
I am trying to search availability of car on given days.
Like if I select Friday then it should return me cars whose quantity more than 0 on Friday but currently it is returning all the cars having quantity 0 as well.
I have written query as below
Car.find({
'active': true,
'model.available': {
$elemMatch: {
quantity: {$gte : 1}
}
}
})
But it returning documents those are having quantity 0 also.

Answer 1

For this, you'll need the aggregation pipeline.
The following code snippet does this:
Find all documents with at least one matching model.
Split up the documents: a document with an array of 3 models in it gets turned into three documents with one model each:
{name: "Car1": 1, models: [{name: "Model1"}, {name: "Model2"}, {name: "Model3"}]}
Becomes:
{name: "Car1", models: {name: "Model1"}} & {name: "Car1", models: {name: "Model2"}} & {name: "Car1", models: {name: "Model3"}}.
The split up documents are filtered (again) on quantity and day.
Optionally, glue the documents back together again. You might not need that in your application.
db.cars.aggregate([
// First, we do your query, which will return
// every document that has _at least one_
// model that is available.
{$match: {
'active': true,
'model.available': {$elemMatch: {
'quantity': {$gte: 1},
'Day': 'Fri'
}}
}},
// We split up the found documents,
// every document will now have exactly
// one 'model' in it.
{$unwind: "$model"},
// We now filter the split documents.
{$match: {
'model.available': {$elemMatch: {
'quantity': {$gte: 1},
'Day': 'Fri'
}}
}},
// If you want, you can now glue the
// models back together again.
{$group: {
_id: "$_id", // Group all documents with the same _id
name: {$first: "$name"},
active: {$first: "$active"},
model: {$push: "$model"} // Make an array of models
}}
])
Important note: For $gte to work, you'll need to store your quantity as a Number, not a String. Since your example has the numbers stored as strings, you might want to double check them in your database.