So I am trying to do something where I can group MongoDB fields for a check.
Given I have following data structure:
{
//Some other data fields
created: date,
lastLogin: date,
someSubObject: {
anotherDate: date,
evenAnotherDate: date
}
On these I want to do a check like this:
collection.aggregate([
{
$match: {
"created": {
$lt: lastWeekDate
},
"someSubObject.anotherDate": {
$lt: lastWeekDate
},
"lastLogin": {
$lt ...
is there a possibility to group the fields and do something like
$match: {
[field1, field2, field3]: {
$lt: lastWeekDate
}
}
You need $expr to use $map to generate an array of boolean values and then $allElementsTrue to apply AND condition
db.collection.find({
$expr: {
$allElementsTrue: {
$map: {
input: [ "$field1", "$field2", "$field3" ],
in: { $lt: [ "$$this", lastWeekDate ] }
}
}
}
})
EDIT: if you need that logic as a part of aggregation you can use $match which is an equivalent of find
db.collection.aggregate([
{
$match: {
$expr: {
$allElementsTrue: {
$map: {
input: [ "$field1", "$field2", "$field3" ],
in: { $lt: [ "$$this", lastWeekDate ] }
}
}
}
}
}
])
Related
I need some help:
I want to optimize this query to be faster , it need to filter by events.eventType:"log" all docs with server:"strong" , but without separate unwind & filter stages , maybe somehow inside the $reduce stage to add $filter.
example single document:
{
server: "strong",
events: [
{
eventType: "log",
createdAt: "2022-01-23T10:26:11.214Z",
visitorInfo: {
visitorId: "JohnID"
}
}
current aggregation query:
db.collection.aggregate([
{
$match: {
server: "strong"
}
},
{
$project: {
total: {
$reduce: {
input: "$events",
initialValue: {
visitor: [],
uniquevisitor: []
},
in: {
visitor: {
$concatArrays: [
"$$value.visitor",
[
"$$this.visitorInfo.visitorId"
]
]
},
uniquevisitor: {
$cond: [
{
$in: [
"$$this.visitorInfo.visitorId",
"$$value.uniquevisitor"
]
},
"$$value.uniquevisitor",
{
$concatArrays: [
"$$value.uniquevisitor",
[
"$$this.visitorInfo.visitorId"
]
]
}
]
}
}
}
}
}
}
])
expected output , two lists with unique visitorId & list of all visitorId:
[
{
"total": {
"uniquevisitor": [
"JohnID"
],
"visitor": [
"JohnID",
"JohnID"
]
}
}
]
playground
In the example query no filter is added for events.eventType:"log" , how can this be implemented without $unwind?
I am not sure this approach is more optimized than yours but might be this will help,
$filter to iterate loop of events and filter by eventType
$let to declare a variable events and store the above filters result
return array of visitor by using dot notation $$events.visitorInfo.visitorId
return array of unique visitor uniquevisitor by using dot notation $$events.visitorInfo.visitorId and $setUnion operator
db.collection.aggregate([
{ $match: { server: "strong" } },
{
$project: {
total: {
$let: {
vars: {
events: {
$filter: {
input: "$events",
cond: { $eq: ["$$this.eventType", "log"] }
}
}
},
in: {
visitor: "$$events.visitorInfo.visitorId",
uniquevisitor: {
$setUnion: "$$events.visitorInfo.visitorId"
}
}
}
}
}
}
])
Playground
Or similar approach without $let and two $project stages,
db.collection.aggregate([
{ $match: { server: "strong" } },
{
$project: {
events: {
$filter: {
input: "$events",
cond: { $eq: ["$$this.eventType", "log"] }
}
}
}
},
{
$project: {
total: {
visitor: "$events.visitorInfo.visitorId",
uniquevisitor: {
$setUnion: "$events.visitorInfo.visitorId"
}
}
}
}
])
Playground
Updated:
I have a document on the database that looks like this:
My question is the following:
How can I retrieve the first 10 elements from the friendsArray from database and sort it descending or ascending based on the lastTimestamp value.
I don't want to download all values to my API and then sort them in Python because that is wasting my resources.
I have tried it using this code (Python):
listOfUsers = db.user_relations.find_one({'userId': '123'}, {'friendsArray' : {'$orderBy': {'lastTimestamp': 1}}}).limit(10)
but it just gives me this error pymongo.errors.OperationFailure: Unknown expression $orderBy
Any answer at this point would be really helpful! Thank You!
use aggregate
first unwind
then sort according timestap
group by _id to create sorted array
use addfields and filter for getting first 10 item of array
db.collection.aggregate([
{ $match:{userId:"123"}},
{
"$unwind": "$friendsArray"
},
{
$sort: {
"friendsArray.lastTimeStamp": 1
}
},
{
$group: {
_id: "$_id",
friendsArray: {
$push: "$friendsArray"
}
},
},
{
$addFields: {
friendsArray: {
$filter: {
input: "$friendsArray",
as: "z",
cond: {
$lt: [
{
$indexOfArray: [
"$friendsArray",
"$$z"
]
},
10
]
}// 10 is n first item
}
}
},
}
])
https://mongoplayground.net/p/2Usk5sRY2L2
and for pagination use this
db.collection.aggregate([
{ $match:{userId:"123"}},
{
"$unwind": "$friendsArray"
},
{
$sort: {
"friendsArray.lastTimeStamp": 1
}
},
{
$group: {
_id: "$_id",
friendsArray: {
$push: "$friendsArray"
}
},
},
{
$addFields: {
friendsArray: {
$filter: {
input: "$friendsArray",
as: "z",
cond: {
$and: [
{
$gt: [
{
$indexOfArray: [
"$friendsArray",
"$$z"
]
},
10
]
},
{
$lt: [
{
$indexOfArray: [
"$friendsArray",
"$$z"
]
},
20
]
},
]
}// 10 is n first item
}
}
},
}
])
The translation of your find to aggregation(we need unwind that why aggregation is used) would be like the bellow query.
Test code here
Query (for descending replace 1 with -1)
db.collection.aggregate([
{
"$match": {
"userId": "123"
}
},
{
"$unwind": {
"path": "$friendsArray"
}
},
{
"$sort": {
"friendsArray.lastTimeStamp": 1
}
},
{
"$limit": 10
},
{
"$replaceRoot": {
"newRoot": "$friendsArray"
}
}
])
If you want to skip some before limit add one stage also
{
"$skip" : 10
}
To take the 10-20 messages for example.
Im trying to create a dynamic group by (with sum agg) in MongoDB. But don't know how to right syntax that.
Lets imaging 2 documents:
{
"_id": {"$oid":"5f69f6a360c8479d0908a649"},
"key":"key1",
"data":{
"key1":"value1",
"key2":"value2",
"key3":"value3",
"key4":"value4"
},
"count":10
}
{
"_id": {"$oid":"5f69f6a360c8479d0908a649"},
"key":"key2",
"data":{
"key1":"value5",
"key2":"value6",
"key3":"value7",
"key4":"value8"
},
"count":15
}
With the key attribute, I want to control, which is the groupby attribute.
A pseudo query could look like:
[{
$group: {
_id: {
'$key': data[$key]
},
sum: {
'$sum': '$count'
}
}
}]
Output should look like:
value1 : 10
value6 : 15
Somebody knows how to do that?
I don't understand the purpose of $sum and $group, there are no arrays in your documents.
This aggregation pipeline give desired result:
db.collection.aggregate([
{ $set: { data: { $objectToArray: "$data" } } },
{ $set: { data: { $filter: { input: "$data", cond: { $eq: ["$$this.k", "$key"] } } } } },
{ $set: { data: { k: { $arrayElemAt: ["$data.v", 0] }, v: "$count" } } },
{ $set: { data: { $arrayToObject: "$data" } } },
{ $replaceRoot: { newRoot: { $mergeObjects: ["$$ROOT", "$data"] } } },
{ $unset: ["key", "count", "data"] }
])
You can try,
$reduce input data as array using $objectToArray, check condition if key matches with data key then return key as value and value as count field
convert that returned key and value object array to exact object using $arrayToObject
replace field using $replaceWith
db.collection.aggregate([
{
$replaceWith: {
$arrayToObject: [
[
{
$reduce: {
input: { $objectToArray: "$data" },
initialValue: {},
in: {
$cond: [
{ $eq: ["$$this.k", "$key"] },
{
k: "$$this.v",
v: "$count"
},
"$$value"
]
}
}
}
]
]
}
}
])
Playground
I have a document like this:
{
value: "field2",
field1: [ ... ],
field2: [ ... ],
...
}
Where value will be the value of one of the fields in the document. and many different fields are possible for one document.
I want to match a document. fetch the relevant field only and them do some calculations on it.
For example I want to do:
{
$unwind: "$value"
}
And get the results of field2 unwinded.
How can I do this?
It's a little bit "hacky" but you can achieve this using operators like $objectToArray and $filter like so:
db.collection.aggregate([
{
$addFields: {
"values": {
$arrayElemAt: [
{
$filter: {
input: {
$objectToArray: "$$ROOT"
},
as: "field",
cond: {
$eq: [
"$$field.k",
"$value"
]
}
}
},
0
]
}
}
},
{
$unwind: "$values.v"
},
{
$replaceRoot: {
newRoot: "$values.v"
}
},
])
MongoPlayground
I have a document structures like this :
{
"_id": xxxxx,
"Name": "John Doe",
"Grades":[
{
"Physics":89,
},
{
"Math":45
},
{
"Chemistry":57
}
]
}
I would like to project grades as an array of only the subjects that have over 60.
I tried this but this didn't work:
$arrayElemAt: [{ $objectToArray: { $gte: ['$hhEthGrp',60] } }, 0]
You definitely need $objectToArray to access a values for unknown keys but you also need $filter for outer array and $anyElementTrue along with $map to determine where there's any value for unknown key which has value over 60:
db.collection.aggregate([
{
$addFields: {
Grades: {
$filter: {
input: "$Grades",
cond: {
$let: {
vars: { kv: { $objectToArray: "$$this" } }
in: {
$anyElementTrue: {
$map: {
input: "$$kv.v",
in: {
$gt: [ "$$this", 60 ]
}
}
}
}
}
}
}
}
}
}
])
Mongo Playground