I have the following code:
const profiles = await Profile.aggregate([
{
$lookup: {
from: "users",
localField: "user",
foreignField: "_id",
as: "user",
},
},
{
$unwind: "$user",
},
{
$match: {
"user.name": {
$regex: q.trim(),
$options: "i",
},
},
},
{
$skip: req.params.page ? (req.params.page - 1) * 10 : 0,
},
{
$limit: 11,
},
{
$group: {
_id: "$_id",
skills:{skills}
user: { name: "$name" },
user: { avatar: "$avatar" },
},
},
]);
I want to return only specific fields like skills _id and user.name and user.avatar, but this doesn't work. I'm pretty sure that the problem is in $group. I want to receive only these fields
[
{
_id: 5ef78d005d23020ca847aa76,
skills: [ 'asd' ],
user: {
_id: 5ef78c7c5d23020ca847aa75,
name: 'Simeon Lazarov',
avatar: 'uploads\\1593286096227 - background.jpg',
}
}
]
You can make use of $project to get specific fields.
After grouping add the below:
{
$project: {_id:1, skills:1, user:1}
}
Projection value of 0 means that the field needs to be excluded, Value 1 represents inclusion of the field.
Document reference: https://docs.mongodb.com/manual/reference/operator/aggregation/project/
Related
I've inherited a Azure Cosmos database with a MongoDB API. There is extensive use of "discriminators" so a single collection has many different models.
I am trying to query a document three levels deep based on document ids (ObjectId())
Parent Group
{
_id: ObjectId(),
__type: "ParentGroup",
name: "group 1",
subgroups: [
...ObjectIds,
],
}
Sub Group
{
_id: ObjectId(),
__type: "SubGroup",
name: "a text name",
members: [
...ObjectIds,
],
}
Member
{
_id: ObjectId(),
__type: "Member",
name: "string",
email: "",
induction: Date,
}
Examples I've seen deal with nested documents NOT references
Is it possible to query the Member documents and return?
[
{
parentGroup,
subgroups: [
{sub group, members: [...members]},
{sub group, members: [...members]},
{sub group, members: [...members]},
]
},
]
After reading the comments and further reading i've got this. Its almost there but I think the limitation of MongoDB will prevent the solution being in a single query. The goal is to return ParentGroups->Subgroups->Members Where Members have an "induction" value of "whatever". I am either returning ALL ParentGroups or nothing at all
db.development.aggregate([
{
$match: {
__type: "ParentGroup", $expr: {
$gt: [
{ $size: "$subgroups" }, 0
]
}
}
},
{
$lookup: {
from: "development",
localField: "subgroups",
foreignField: "_id",
as: "subgroups"
}
},
{
$unwind: {
path: "$subgroups",
// preserveNullAndEmptyArrays: true
}
},
{
$lookup: {
from: "development",
localField: "subgroups.members",
foreignField: "_id",
as: "subgroups.members"
}
}
])
Solution that worked for me:
db.development.aggregate([
{
$match: {
__type: "ParentGroup",
},
},
{
$lookup: {
from: "development",
localField: "subgroups",
foreignField: "_id",
as: "subgroups",
},
},
{
$unwind: {
path: "$subgroups",
preserveNullAndEmptyArrays: true,
},
},
{
$lookup: {
from: "development",
localField: "subgroups.members",
foreignField: "_id",
as: "subgroups.activities_x",
},
},
{
$unwind: {
path: "$subgroups.members",
preserveNullAndEmptyArrays: true,
},
},
{
$match: { "subgroups.members.meta": { $exists: true } },
},
{
$project: {
_id: 1,
__type: 1,
name: 1,
subgroups: {
_id: 1,
__type: 1,
name: 1,
members: {
_id: 1,
__type: 1,
name: 1,
meta: 1,
},
},
},
},
]);
I use Atlas Search to return a list of documents (using Mongoose):
const searchResults = await Resource.aggregate()
.search({
text: {
query: searchQuery,
path: ["title", "tags", "link", "creatorName"],
},
}
)
.match({ approved: true })
.addFields({
score: { $meta: "searchScore" }
})
.exec();
These resources can be up and downvoted by users (like questions on Stackoverflow). I want to boost the search score depending on these votes.
I can use the boost operator for that.
Problem: The votes are not a property of the Resource document. Instead, they are stored in a separate collection:
const resourceVoteSchema = mongoose.Schema({
_id: { type: String },
userId: { type: mongoose.Types.ObjectId, required: true },
resourceId: { type: mongoose.Types.ObjectId, required: true },
upDown: { type: String, required: true },
After I get my search results above, I fetch the votes separately and add them to each search result:
for (const resource of searchResults) {
const resourceVotes = await ResourceVote.find({ resourceId: resource._id }).exec();
resource.votes = resourceVotes
}
I then subtract the downvotes from the upvotes on the client and show the final number in the UI.
How can I incorporate this vote points value into the score of the search results? Do I have to reorder them on the client?
Edit:
Here is my updated code. The only part that's missing is letting the resource votes boost the search score, while at the same time keeping all resource-votes documents in the votes field so that I can access them later. I'm using Mongoose syntax but an answer with normal MongoDB syntax will work for me:
const searchResults = await Resource.aggregate()
.search({
compound: {
should: [
{
wildcard: {
query: queryStringSegmented,
path: ["title", "link", "creatorName"],
allowAnalyzedField: true,
}
},
{
wildcard: {
query: queryStringSegmented,
path: ["topics"],
allowAnalyzedField: true,
score: { boost: { value: 2 } },
}
}
,
{
wildcard: {
query: queryStringSegmented,
path: ["description"],
allowAnalyzedField: true,
score: { boost: { value: .2 } },
}
}
]
}
}
)
.lookup({
from: "resourcevotes",
localField: "_id",
foreignField: "resourceId",
as: "votes",
})
.addFields({
searchScore: { $meta: "searchScore" },
})
.facet({
approved: [
{ $match: matchFilter },
{ $skip: (page - 1) * pageSize },
{ $limit: pageSize },
],
resultCount: [
{ $match: matchFilter },
{ $group: { _id: null, count: { $sum: 1 } } }
],
uniqueLanguages: [{ $group: { _id: null, all: { $addToSet: "$language" } } }],
})
.exec();
It could be done with one query only, looking similar to:
Resource.aggregate([
{
$search: {
text: {
query: "searchQuery",
path: ["title", "tags", "link", "creatorName"]
}
}
},
{$match: {approved: true}},
{$addFields: {score: {$meta: "searchScore"}}},
{
$lookup: {
from: "ResourceVote",
localField: "_id",
foreignField: "resourceId",
as: "votes"
}
}
])
Using the $lookup step to get the votes from the ResourceVote collection
If you want to use the votes to boost the score, you can replace the above $lookup step with something like:
{
$lookup: {
from: "resourceVote",
let: {resourceId: "$_id"},
pipeline: [
{
$match: {$expr: {$eq: ["$resourceId", "$$resourceId"]}}
},
{
$group: {
_id: 0,
sum: {$sum: {$cond: [{$eq: ["$upDown", "up"]}, 1, -1]}}
}
}
],
as: "votes"
}
},
{$addFields: { votes: {$arrayElemAt: ["$votes", 0]}}},
{
$project: {
"wScore": {
$ifNull: [
{$multiply: ["$score", "$votes.sum"]},
"$score"
]
},
createdAt: 1,
score: 1
}
}
As you can see on this playground example
EDIT: If you want to keep the votes on the results, you can do something like:
db.searchResults.aggregate([
{
$lookup: {
from: "ResourceVote",
localField: "_id",
foreignField: "resourceId",
as: "votes"
}
},
{
"$addFields": {
"votesCount": {
$reduce: {
input: "$votes",
initialValue: 0,
in: {$add: ["$$value", {$cond: [{$eq: ["$$this.upDown", "up"]}, 1, -1]}]}
}
}
}
},
{
$addFields: {
"wScore": {
$add: [{$multiply: ["$votesCount", 0.1]}, "$score"]
}
}
}
])
As can be seen here
Hello i am trying to join two collections...
#COLLECTION 1
const valuesSchema= new Schema({
value: { type: String },
})
const categoriesSchema = new Schema({
name: { type: String },
values: [valuesSchema]
})
mongoose.model('categories', categoriesSchema )
#COLLECTION 2
const productsSchema = new Schema({
name: { type: String },
description: { type: String },
categories: [{
type: mongoose.Schema.Types.ObjectId,
ref: 'categories',
}]
})
mongoose.model('productos', productsSchema )
Now, what i pretend to do is join these collections and have an output like this.
#Example Product Document
{
name: 'My laptop',
description: 'Very ugly laptop',
categories: ['5f55949054f3f31db0491b5c','5f55949054f3f31db0491b5b'] // these are _id of valuesSchema
}
#Expected Output
{
name: 'My laptop',
description: 'Very ugly laptop',
categories: [{value: 'Laptop'}, {value: 'PC'}]
}
This is what i tried.
{
$lookup: {
from: "categories",
let: { "categories": "$categories" },
as: "categories",
pipeline: [
{
$match: {
$expr: {
$in: [ '$values._id','$$categories']
},
}
},
]
}
}
but this query is not matching... Any help please?
You can try,
$lookup with categories
$unwind deconstruct values array
$match categories id with value id
$project to show required field
db.products.aggregate([
{
$lookup: {
from: "categories",
let: { cat: "$categories" },
as: "categories",
pipeline: [
{ $unwind: "$values" },
{ $match: { $expr: { $in: ["$values._id", "$$cat"] } } },
{
$project: {
_id: 0,
value: "$values.value"
}
}
]
}
}
])
Playground
Since you try to use the non-co-related queries, I appreciate it, you can easily achieve with $unwind to flat the array and then $match. To regroup the array we use $group. The $reduce helps to move on each arrays and store some particular values.
[
{
$lookup: {
from: "categories",
let: {
"categories": "$categories"
},
as: "categories",
pipeline: [
{
$unwind: "$values"
},
{
$match: {
$expr: {
$in: [
"$values._id",
"$$categories"
]
},
}
},
{
$group: {
_id: "$_id",
values: {
$addToSet: "$values"
}
}
}
]
}
},
{
$project: {
categories: {
$reduce: {
input: "$categories",
initialValue: [],
in: {
$concatArrays: [
"$$this.values",
"$$value"
]
}
}
}
}
}
]
Working Mongo template
I am creating a platform where people can share their memes. On one page I want to show them who are the most popular members on the platform. so, there is a collection of 'meme' and 'user'
for example,
There is two content with same ids:
{
_id: 1,
username: "name",
bio: "bio",
image: "url",
};
memes
{
_id: 0,
user_id: 1,
image: "meme1.jpg",
likes: [
{
user_id: 4
}
]
},
{
_id: 1,
user_id: 1,
image: "meme2.jpg",
likes: [
{
user_id: 5
},
{
user_id: 6
}
]
}
and I want to output something like this way
{
user_id:1,
username:"name"
likes:3,
}
I wrote this query using aggregate functions but I am not understanding how to identify ids are the same or not?
meme
.aggregate([
{
$lookup: {
from: "users",
localField: "user_id",
foreignField: "_id",
as: "userDetails",
},
},
{
$project: {
user_id: "$user_id",
username: "$userDetails.username",
likes: {
$size: "$likes",
},
},
},
{
$sort: { likes: 1 },
},
])
.exec()
.then((result) => {
console.log(result);
});
It will be easier to start query with users.
You can use $sum, $map, $size aggregations to get the total likes, and add it using $addFields.
db.users.aggregate([
{
$lookup: {
from: "memes",
localField: "_id",
foreignField: "user_id",
as: "userDetails"
}
},
{
$addFields: {
"likes": {
"$sum": {
"$map": {
"input": "$userDetails",
"in": {
"$size": "$$this.likes"
}
}
}
}
}
},
{
$project: {
_id: 0,
user_id: "$_id",
username: 1,
likes: 1
}
}
])
Playground
Result:
[
{
"likes": 3,
"user_id": 1,
"username": "name"
}
]
You could project the length of the likes-array and group each projection by the user_id and cound the results. Something like this should work:
db.getCollection('memes').aggregate([{
$lookup: {
from: "users",
localField: "user_id",
foreignField: "_id",
as: "userDetails"
}
}, {
"$project": {
"user_id": 1,
"likesSize": {
"$size": "$likes"
}
}
}, {
$group: {
_id: "$user_id",
"count": {
"$sum": "$likesSize"
}
}
}
])
The above query should return:
{
"_id" : 1,
"count" : 3
}
For some reason, I can't retrieve the author name from another collection on my aggregate query.
db.getCollection('books').aggregate([
{
$match: {
authorId: { $nin: [ObjectId('5b9a008575c50f1e6b02b27b'), ObjectId('5ba0fb3275c50f1e6b02b2f5'), ObjectId('5bc058b6ae9a2a4d6df330b1')]},
isBorrowed: { $in: [null, false] },
status: 'ACTIVE',
},
},
{
$lookup: {
from: "authors",
localField: "authorId", // key of author id in "books" collection
foreignField: "_id", // key of author id in "authors" collection
as: "bookAuthor",
}
},
{
$group: {
_id: {
author: '$authorId',
},
totalSalePrice: {
$sum: '$sale.amount',
},
},
},
{
$project: {
author: '$_id.author',
totalSalePrice: '$totalSalePrice',
authorName: '$bookAuthor.name', // I can't make this appear
_id: 0,
},
},
{ $sort: { totalSalePrice: -1 } },
])
Any advice on where I had it wrong? Thanks for the help.
Two things that are missing here: you need $unwind to convert bookAuthor from an array into single object and then you need to add that object to your $group stage (so that it will be available in next stages), try:
db.getCollection('books').aggregate([
{
$match: {
authorId: { $nin: [ObjectId('5b9a008575c50f1e6b02b27b'), ObjectId('5ba0fb3275c50f1e6b02b2f5'), ObjectId('5bc058b6ae9a2a4d6df330b1')]},
isBorrowed: { $in: [null, false] },
status: 'ACTIVE',
},
},
{
$lookup: {
from: "authors",
localField: "authorId",
foreignField: "_id",
as: "bookAuthor", // this will be an array
}
},
{
$unwind: "$bookAuthor"
},
{
$group: {
_id: {
author: '$authorId',
},
bookAuthor: { $first: "$bookAuthor" },
totalSalePrice: {
$sum: '$sale.amount',
},
},
},
{
$project: {
author: '$_id.author',
totalSalePrice: '$totalSalePrice',
authorName: '$bookAuthor.name',
_id: 0,
},
},
{ $sort: { totalSalePrice: -1 } },
])
Actually you have lost the bookAuthor field in the $group stage. You have to use $first accumulator to get it in the next $project stage.
{ "$group": {
"_id": { "author": "$authorId" },
"totalSalePrice": { "$sum": "$sale.amount" },
"authorName": { "$first": "$bookAuthor" }
}},
{ "$project": {
"author": "$_id.author",
"totalSalePrice": "$totalSalePrice",
"authorName": { "$arrayElemAt": ["$bookAuthor.name", 0] }
"_id": 0,
}}