I want to project a collection applying exporting a value only if a field is inside a range.
Sort of:
db.workouts.aggregate({
$match: { user_id: ObjectId(".....") }
},
{
$project: {
'20': { $cond: [ {$gt: [ "$avg_intensity", 20]} , '$total_volume', 0] }
}
})
I need to get the value only if the avg_intensity is inside a certain range. I will then group and sum on the projection result.
What I am trying to do is applying a $gt and $lt filter but with no much success.
db.workouts.aggregate(
{
$match: { user_id: ObjectId("....") }
},
{
$project: {
'20': { $cond: [ [{$gt: [ "$avg_intensity", 20]}, {$lt: [ "$avg_intensity", 25]}] , '$total_volume', 0] }
}
})
How may I apply both $gt and $lt conditions?
To combine logical conditions under a $cond
operator then wrap the conditions with an $and
operator:
db.workouts.aggregate([
{ "$match": { "user_id": ObjectId("....") }},
{ "$project": {
"20": { "$cond": [
{ "$and": [
{ "$gt": [ "$avg_intensity", 20 ] },
{ "$lt": [ "$avg_intensity", 25 ] }
]},
"$total_volume",
0
]}
}}
])
If I got your requirements right you should put the filter in the match part of the pipeline:
db.workouts.aggregate( [
{ $match: { user_id: ObjectId("...."), "avg_intensity": { $gt: 20, $lte: 25 } } },
{ $group: { _id: ..., count: ... } }
] );
In the following way we can aggregate, Here i using two conditions which are city,year
db.getCollection('geolocations').aggregate(
[{$unwind : '$geolocation'},
{
$group:
{
_id: {city:"$geolocation.city",year: { $year: "$geolocation.date" }},
count: { $sum: 1 }
}
}
]
)
Output:
/* 1 */
{
"_id" : {
"city" : "Noida",
"year" : 2020
},
"count" : 1.0
}
/* 2 */
{
"_id" : {
"city" : "Villupuram",
"year" : 2020
},
"count" : 1.0
}
/* 3 */
{
"_id" : {
"city" : "Chennai",
"year" : 2020
},
"count" : 2.0
}