In my application i have a collection called Blog and i run this query every 24h
await Blog.updateMany({}, [
{
$set: {
viewed: {
$add: [{ $size: "$visitorIps" }, "$viewed"]
},
visitorIps: []
}
}
]);
My problem is that i have a second collection called Users.
Inside of Users i have an array called posts and here are all posts from that user saved.
{
_id: 234klj2ö34,
user: "Max",
posts: [
{
_id: 5dgewef323523,
name: "My first blogpost",
content: "...",
viewed: 0,
visitorIps: ["192.168.23.12"]
}
]
}
Now i need the same query on my second collection for each array. How do i do it? I tried something like this but it doesnt worked:
await User.updateMany({}, [
{
$set: {
"posts.$[].viewed: {
$add: [{ $size: "posts.$[].visitorIps" }, "posts.$[].viewed"]
},
"posts.$[].visitorIps": []
}
}
]);
But thats completely wrong. Could somebody help me here out?
You can try using $map,
your logic and code remain same for viewed and visitorIps
$mergeObjects will merge current cursor fields and viewed and visitorIps that we have calculated
await User.updateMany({},
[{
$set: {
posts: {
$map: {
input: "$posts",
as: "post",
in: {
$mergeObjects: [
"$$post",
{
"viewed": {
$add: [{ $size: "$$post.visitorIps" }, "$$post.viewed"]
},
"visitorIps": []
}
]
}
}
}
}
}]
)
Related
I have a collection of documents ChatRooms in MongoDB that has this (simplified) structure:
{
_id: ObjectId('4654'),
messages: [
{
user: ObjectId('1234'),
sentAt: ISODate('2022-03-01T00:00:00.000Z')
},
{
user: ObjectId('1234'),
sentAt: ISODate('2022-03-02T00:00:00.000Z')
},
{
user: ObjectId('8888'),
sentAt: ISODate('2022-03-03T00:00:00.000Z')
},
]
}
What I'm trying to achieve is to filter the messages array inside the aggregate pipeline in order to get an array where the userId is presend just once. The result I'm looking for is (or something similar but the array shouldn't have two elements with the same user id):
{
_id: ObjectId('4654'),
messages: [
{
user: ObjectId('1234'),
sentAt: ISODate('2022-03-01T00:00:00.000Z')
},
{
user: ObjectId('8888'),
sentAt: ISODate('2022-03-03T00:00:00.000Z')
},
]
}
Is such a thing possible even?
Any help would be much appreciated.
You can do this in several different ways, here is an example of how to achieve this using the $reduce operator:
db.collection.aggregate([
{
$addFields: {
messages: {
$reduce: {
input: "$messages",
initialValue: [],
in: {
$cond: [
{
$in: [
"$$this.user",
"$$value.user"
]
},
"$$value",
{
"$concatArrays": [
"$$value",
[
"$$this"
]
]
}
]
}
}
}
}
}
])
Mongo Playground
I have a collection of documents, which I need to first narrow down by set criteria, then sort alphabetically by string value inside those documents — let's say that's a "search result". I then need to find document that matches a given _id and then pick a document next to it (before or after) from the above "search result".
Background:
I use mongoose to query my database via Node.js.
I have a set of "special sections" in my blog that are comprised of all the articles that must have three particular conditions associated within the keys in the document. I can get the list of articles belonging to said section like so:
const specialSectionListQuery = Article.find({
tag: { $ne: "excluded" },
[`collections.cameras`]: { $exists: true },
status: "published",
})
To finish creating the "special section," I must sort the documents alphabetically via their title attribute:
.sort({ [`collections.cameras.as.title`]: "asc" })
Now I want to add a link to "next article within the same special section" at the bottom of such articles. I know _id and any other value needed from the current article. The above query gives me an ordered list of documents within the section so I can easily find it within that list specialSectionListQuery.findOne({ _id: "xxx" }).exec().
However, I need to find the next article within the above list. How do I do that?
My attempts thus far:
I tried to create article list via aggregation, which led me nowhere (I simply made my app do exactly the same thing — make a list for a "special sectin"):
Article.aggregate([
{
$match: {
tag: { $ne: "excluded" },
[`collections.cameras`]: { $exists: true },
status: "published",
},
},
{
$sort: {
[`collections.cameras.as.title`]: 1,
},
}
]).exec()
But I can't for the life of me figure out how to iterate to the next document in the list properly.
I have thought of saving the list in Node.js memory (variable) and then finding what I need via JavaScript but that can't be scalable.
I have considered creating a new collection and saving the above list there but that would require me to either 1) do it every time a document is altered/added/deleted via Node.js — which is a lot of code and it may break if I interact with database another way 2) rebuild the colleciton every time I run the query, but that feels like it'll lack in performance.
Please help and thank you!
P.S.:
Example collection which should cover most of the cases I'm looking to solve for:
[
{
_id: 1,
name: "Canon",
collections: { cameras: { as: { title: "Half-Frame" } } },
tag: "included",
status: "published"
},
{
_id: 2,
name: "Pentax",
collections: { cameras: { as: { title: "Full-Frame" } } },
tag: "included",
status: "published"
},
{
_id: 3,
name: "Kodak",
collections: { film: { as: { title: "35mm Film" } } },
tag: "included",
status: "published"
},
{
_id: 4,
name: "Ricoh",
collections: { cameras: { as: { title: "Full-Frame" } } },
tag: "included",
status: "published"
},
{
_id: 5,
name: "Minolta",
collections: { cameras: { as: { title: "Half-Frame Review" } } },
tag: "excluded",
status: "published"
},
{
_id: 4,
name: "FED",
collections: { cameras: { as: { title: "Full-Frame" } } },
tag: "included",
status: "draft"
}
]
One thing you can try is to extend your $sort by adding _id so that it always returns documents in deterministic order:
{
$sort: {
"collections.cameras.as.title": 1,
_id: 1
}
},
{
$limit: 1
}
Once your first query returns the document with _id: 2 and collections.cameras.as.title: Full-Frame, you can use below query to get subsequent document:
{
$match: {
$and: [
{
tag: { $ne: "excluded" },
"collections.cameras": { $exists: true },
status: "published",
},
{
$or: [
{
$and: [
{ "collections.cameras.as.title": { $eq: "Full-Frame" } },
{ "_id": { $gt: 2 } }
]
},
{ "collections.cameras.as.title": { $gt: "Full-Frame" } }
]
}
]
}
},
{
$sort: {
"collections.cameras.as.title": 1,
_id: 1
}
},
{
$limit: 1
}
In this case due to deterministic $sort you can exclude previously found document by adding additional filtering criteria and the order should be preserved.
Mongo Playground
I have an array of objects call "extra" with different properties: some objects have "plus" and some haven't.
I want to create inside this "extra" array, 2 different arrays one called "cheap" with all the object that don't have the "plus" property and one called "exp" with only the objects with the "plus" property.
I think I can use the $reduce method in mongodb aggregate with $concatArrays and check with $cond if the property plus exists or not.
Something like that:
Data example:
{
extra: [
{
description: "laces",
type: "exterior",
plus: '200'
},
{
description: "sole",
type: "interior"
},
{
description: "logo",
type: "exterior"
},
{
description: "stud",
type: "exterior",
plus: '450'
}
],
}
{
$project: {
extra: {
$reduce: {
input: ['$extra'],
initialValue: {cheap: [], exp: []},
$cond: {
if: {$eq: ['$$this.plus', null]},
then: {
in: {
cheap: {
$concatArrays: ['$$value.cheap', '$$this'],
},
},
},
else: {
in: {
exp: {
$concatArrays: ['$$value.exp', '$$this'],
},
},
},
},
},
},
},
}
It doesn't work...I tried many ways or writing the $cond part without luck.
I can't figure it out.
Thank you all.
K.
Apart from some minor syntax issues you've had another problem is your understand of the $ne operator.
In this case you expect a missing value to be equal to null, this is not how Mongo works. so for a document:
{ name: "my name" }
The aggregation query:
{ $cond: { $eq: ["$missingField", null] } }
Will not give true as you expect as missing is not equal to null. I took the liberty to fix the syntax issues you've had, this working pipeline is the way to go:
db.collection.aggregate([
{
$project: {
extra: {
$reduce: {
input: "$extra",
initialValue: {
cheap: [],
exp: []
},
in: {
cheap: {
"$concatArrays": [
"$$value.cheap",
{
$cond: [
"$$this.plus",
[],
[
"$$this"
],
]
}
]
},
exp: {
"$concatArrays": [
"$$value.exp",
{
$cond: [
"$$this.plus",
[
"$$this"
],
[]
]
}
]
}
}
},
},
},
}
])
Mongo Playground
One thing to note is that $cond evaluates the plus field, meaning if the field does exist with a null value or a 0 value then it will consider this document matched for the cheap array. This is something to consider and change in case these are possible.
I have a schema like below:
[
{
"_id": 1,
"showResult": true,
"subject": "History",
},
{
"_id": 2,
"showResult": false,
"subject": "Math",
}
]
and an object in JS like below:
result = {
"History": 22,
"Math": 18
}
I am using aggregate to process query, in between i need to find score based on subject field in the document if showResult field is true i.e to access result variable inside query as map result[$subject]
My query:
db.collection.aggregate([
{
"$project": {
_id: 1,
"score":{$cond: { if: { $eq: [ "$showResult", true ] }, then: subjectObj[$subject], else: null }}
}
}
])
can this be done in MongoDB, i want result like below:
{
_id: 1,
score: 22
}
I think query is little costly than JS code, but i am adding the query if it will help you as per your question,
$match showResult is true
$project to show required fields, $reduce to iterate loop of result after converting from object to array using $objectToArray, check condition if subject match then return matching score
let result = {
"History": 22,
"Math": 18
};
db.collection.aggregate([
{ $match: { showResult: true } },
{
$project: {
_id: 1,
score: {
$reduce: {
input: { $objectToArray: result },
initialValue: 0,
in: {
$cond: [{ $eq: ["$$this.k", "$subject"] }, "$$this.v", "$$value"]
}
}
}
}
}
])
Playground
I am new to MongoDB and I am stuck in the below scenario.
I have a collection that contains duplicate docs.
I just want to get the sum of the property in each doc excluding the duplicate docs.
My Docs looks like this:
{"_id":"5dd629461fc50b782479ea90",
"referenceId":"5dd581f10859d2737965d23a",
"sellingId":"319723fb80b1a297cf0803abad9bc60787537f14a6a37d6e47",
"account_name":"mrfsahas1234",
"vendor_name":"testaccount2",
"action_type":"purchase",
"product_name":"Bottle",
"product_quantity":10,
"transactionId":"319723fb80b1a297cf0803abad9bc60787537f14a6a37d6e47",
"uid":"2019-11-20T17:39:17.405Z",
"createdAt":"2019-11-21T08:56:56.589+00:00",
"updatedAt":"2019-11-21T08:56:56.589+00:00","__v":0
},
{
"_id":"5dd629461fc50b782479ea90",
"referenceId":"5dd581f10859d2737965d23a",
"sellingId":"320a9a2f814a45e01eb98344c9af708fa2864d81587e5914",
"account_name":"mrfsahas1234",
"vendor_name":"testaccount2",
"action_type":"purchase",
"product_name":"Bottle",
"product_quantity":50,
"transactionId":"320a9a2f814a45e01eb98344c9af708fa2864d81587e5914",
"uid":"2019-11-20T17:39:17.405Z",
},
{
"_id":"5dd629461fc50b782479ea90",
"referenceId":"5dd581f10859d2737965d23a",
"sellingId":"320a9a2f814a45e01eb98344c9af708fa2864d81587e5914",
"account_name":"mrfsahas1234",
"vendor_name":"testaccount2",
"action_type":"purchase",
"product_name":"Bottle",
"product_quantity":50,
"transactionId":"320a9a2f814a45e01eb98344c9af708fa2864d81587e5914",
"uid":"2019-11-20T17:39:17.405Z",
},
Currently, I am doing this:
MaterialsTrack.aggregate([
{
$match: {
$and: [
{product_name: product_name},
{account_name: account_name},
{action_type: 'purchase'},
{uid:uid}
]
}
},
{
$group: {_id: "$sellingId", PurchseQuantity: {$sum: "$product_quantity"}}
},
])
It returns the sum of product_quantity all the matching docs (including the duplicate docs).
Current Output:
{_id: "320a9a2f814a45e01eb98344c9af708fa2864d81587e5914", PurchseQuantity:110}
Expected Output:
{_id: "320a9a2f814a45e01eb98344c9af708fa2864d81587e5914", PurchseQuantity:60}
I want to get the sum of only unique docs. How can I achieve it?
Thanks in advance!
You need to sum inside of the $group _id field, and then use the replaceRoot to achieve the the result you wanted.
MaterialsTrack.aggregate([
{
$match: {
$and: [
{
product_name: "Bottle"
},
{
account_name: "mrfsahas1234"
},
{
action_type: "purchase"
},
{
uid: "2019-11-20T17:39:17.405Z"
}
]
}
},
{
$group: {
_id: {
sellingId: "$sellingId",
PurchaseQuantity: {
$sum: "$product_quantity"
}
}
}
},
{
$replaceRoot: {
newRoot: {
_id: "$_id.sellingId",
PurchaseQuantity: "$_id.PurchaseQuantity"
}
}
}
]);
Sample Output:
[
{
"PurchaseQuantity": 50,
"_id": "320a9a2f814a45e01eb98344c9af708fa2864d81587e5914"
}
]
Playground:
https://mongoplayground.net/p/MOneCRiSlO0
What about adding $addToSet to your aggregations pipeline
MaterialsTrack.aggregate([
{
$match: {
$and: [
{product_name: product_name},
{account_name: account_name},
{action_type: 'purchase'},
{uid:uid}
]
}
},
{
$group: {_id: "$sellingId", PurchseQuantity: {$sum: "$product_quantity"},"list" : {$addToSet : "$list"}}
},
])