Related
This is Code in node js
const result = await OrderDB.aggregate([
{ $match: { _id: mongoose.Types.ObjectId(id) } },
{
$lookup: {
from: 'products',
localField: 'product',
foreignField: '_id',
as: 'productDetail',
},
},
{
$project: {
productDetail: {
name: 1,
price: 1,
productImage: 1,
},
},
},
])
This is the response of code
{
"message": "Get Order Successfully",
"result": [
{
"_id": "5ff47348db5f5917f81871aa",
"productDetail": [
{
"name": "Camera",
"productImage": [
{
"_id": "5fe9b8a26720f728b814e246",
"img": "uploads\\product\\7Rq1v-app-7.jpg"
},
{
"_id": "5fe9b8a26720f728b814e247",
"img": "uploads\\product\\FRuVb-app-8.jpg"
}
],
"price": 550
}
]
}
]
}
I want to display only one productImage from the response using nodejs and mongoose
This is using in aggregate projection
I was use $arrayElemAt but it is don't work
I also use $first but it is don't work
so projection method I use to display only one *productImage*
Data looks like multi level nested.
You have array of results, each result contains array of productDetails
play
You need to unwind the data to get the first productImage
db.collection.aggregate([
{
"$unwind": "$result"
},
{
"$unwind": "$result.productDetail"
},
{
$project: {
pImage: {
"$first": "$result.productDetail.productImage"
}
}
}
])
With the above response
db.collection.aggregate([
{
"$project": {
productDetails: {
$map: {
input: "$productDetail",
in: {
"$mergeObjects": [
"$$this",
{
productImage: {
"$arrayElemAt": [
"$$this.productImage",
0
]
}
}
]
}
}
}
}
}
])
Working Mongo playground
This question is a follow up to a previous question for which I have accepted an answer already. I have an aggregate query that returns the results of a deeply nested array of subdocuments based on a date range. The query returns the correct results within the specified date range, however it also returns an empty array for the results that do not match the query.
Technologies: MongoDB 3.6, Mongoose 5.5, NodeJS 12
Question 1:
Is there any way to remove the results that don't match the query?
Question 2:
Is there any way to 'populate' the Person db reference in the results? For example to get the Person Display Name I usually use 'populate' such as find().populate({ path: 'Person', select: 'DisplayName'})
Records schema
let RecordsSchema = new Schema({
RecordID: {
type: Number,
index: true
},
RecordType: {
type: String
},
Status: {
type: String
},
// ItemReport array of subdocuments
ItemReport: [ItemReportSchema],
}, {
collection: 'records',
selectPopulatedPaths: false
});
let ItemReportSchema = new Schema({
// ObjectId reference
ReportBy: {
type: Schema.Types.ObjectId,
ref: 'people'
},
ReportDate: {
type: Date,
required: true
},
WorkDoneBy: [{
Person: {
type: Schema.Types.ObjectId,
ref: 'people'
},
CompletedHours: {
type: Number,
required: true
},
DateCompleted: {
type: Date
}
}],
});
Query
Works but also returns empty results and also need to populate the Display Name property of the Person db reference
db.records.aggregate([
{
"$project": {
"ItemReport": {
$map: {
input: "$ItemReport",
as: "ir",
in: {
WorkDoneBy: {
$filter: {
input: "$$ir.WorkDoneBy",
as: "value",
cond: {
"$and": [
{ "$ne": [ "$$value.DateCompleted", null ] },
{ "$gt": [ "$$value.DateCompleted", new Date("2017-01-01T12:00:00.000Z") ] },
{ "$lt": [ "$$value.DateCompleted", new Date("2018-12-31T12:00:00.000Z") ] }
]
}
}
}
}
}
}
}
}
])
Actual Results
{
"_id": "5dcb6406e63830b7aa5427ca",
"ItemReport": [
{
"WorkDoneBy": [
{
"_id": "5dcb6406e63830b7aa53d8ea",
"PersonID": 111,
"ReportID": 8855,
"CompletedHours": 3,
"DateCompleted": "2017-01-20T05:00:00.000Z",
"Person": "5dcb6409e63830b7aa54fdba"
}
]
}
]
},
{
"_id": "5dcb6406e63830b7aa5427f1",
"ItemReport": [
{
"WorkDoneBy": [
{
"_id": "5dcb6406e63830b7aa53dcdc",
"PersonID": 4,
"ReportID": 9673,
"CompletedHours": 17,
"DateCompleted": "2017-05-18T04:00:00.000Z",
"Person": "5dcb6409e63830b7aa54fd69"
},
{
"_id": "5dcb6406e63830b7aa53dcdd",
"PersonID": 320,
"ReportID": 9673,
"CompletedHours": 3,
"DateCompleted": "2017-05-18T04:00:00.000Z",
"Person": "5dcb6409e63830b7aa54fe88"
}
]
}
]
},
{
"_id": "5dcb6406e63830b7aa5427f2",
"ItemReport": [
{
"WorkDoneBy": []
}
]
},
{
"_id": "5dcb6406e63830b7aa5427f3",
"ItemReport": [
{
"WorkDoneBy": []
}
]
},
{
"_id": "5dcb6406e63830b7aa5427f4",
"ItemReport": [
{
"WorkDoneBy": []
}
]
},
{
"_id": "5dcb6406e63830b7aa5427f5",
"ItemReport": [
{
"WorkDoneBy": []
}
]
},
Desired results
Note the results with an empty "WorkDoneBy" array are removed (question 1), and the "Person" display name is populated (question 2).
{
"_id": "5dcb6406e63830b7aa5427f1",
"ItemReport": [
{
"WorkDoneBy": [
{
"_id": "5dcb6406e63830b7aa53dcdc",
"CompletedHours": 17,
"DateCompleted": "2017-05-18T04:00:00.000Z",
"Person": {
_id: "5dcb6409e63830b7aa54fe88",
DisplayName: "Joe Jones"
}
},
{
"_id": "5dcb6406e63830b7aa53dcdd",
"CompletedHours": 3,
"DateCompleted": "2017-05-18T04:00:00.000Z",
"Person": {
_id: "5dcb6409e63830b7aa54fe88",
DisplayName: "Alice Smith"
}
}
]
}
]
},
First question is relatively easy to answer and there are multiple ways to do that. I would prefer using $anyElementTrue along with $map as those operators are pretty self-explanatory.
{
"$match": {
$expr: { $anyElementTrue: { $map: { input: "$ItemReport", in: { $gt: [ { $size: "$$this.WorkDoneBy" }, 0 ] } } } }
}
}
MongoPlayground
Second part is a bit more complicated but still possible. Instead of populate you need to run $lookup to bring the data from other collection. The problem is that your Person values are deeply nested so you need to prepare a list of id values before using $reduce and $setUnion. Once you get the data you need to merge your nested objects with people entities using $map and $mergeObjects.
{
$addFields: {
people: {
$reduce: {
input: "$ItemReport",
initialValue: [],
in: { $setUnion: [ "$$value", "$$this.WorkDoneBy.Person" ] }
}
}
}
},
{
$lookup: {
from: "people",
localField: "peopleIds",
foreignField: "_id",
as: "people"
}
},
{
$project: {
_id: 1,
ItemReport: {
$map: {
input: "$ItemReport",
as: "ir",
in: {
WorkDoneBy: {
$map: {
input: "$$ir.WorkDoneBy",
as: "wdb",
in: {
$mergeObjects: [
"$$wdb",
{
Person: { $arrayElemAt: [{ $filter: { input: "$people", cond: { $eq: [ "$$this._id", "$$wdb.Person" ] } } } , 0] }
}
]
}
}
}
}
}
}
}
}
Complete Solution
This question already has answers here:
Find in Double Nested Array MongoDB
(2 answers)
Closed 3 years ago.
My model called Residence
{
"_id": { "$oid": "5d88dfe45feb4c06a5cfb762" },
"spaces": [{
"_id": { "$oid": "5d88dfe45feb4c06a5cfb76f" },
"name": "Building 2",
"subSpace": [
{
"_id": { "$oid": "5d88dfe45feb4c06a5cfb771" },
"name": "Basement"
},
{
"_id": { "$oid": "5d88dfe45feb4c06a5cfb770" },
"name": "Floors" // Get only the name by Id
}
]
}
}
To find a spaceName by Id (OK)
exports.getSpaceNameById = (spaceId) => {
return Residence.find({ 'spaces._id': spaceId }, { _id: 0, spaces: { $elemMatch: { _id: spaceId } } })
}
Now I want to have the subSpace name requested by Id.
But my dream would be to have both (query by subSpace Id, for this example : 5d88dfe45feb4c06a5cfb770) : spaceName / subSpaceName only with 1 request.
Thanks for your help.
UPDATE 1
I try this method but the response is an empty array
exports.getSubSpaceNameById = (spaceId) => {
return Residence.aggregate([
{ $match: {'spaces.subSpace._id': spaceId}},
{ $project: {
'spaces.subSpace': { $filter: {
input: '$spaces.subSpace',
as: 'mySubSpace',
cond: { $eq: ['$$mySubSpace._id', spaceId]}
}},
_id: 0
}}
])
}
The following should work for you. This query would return the whole document.
By name:
db.collection.find({"spaces.subSpace.name": "Basement"})
By _id: db.collection.find({"spaces.subSpace._id": "YOUR_ID"})
Try this query
db.testers.aggregate([
{
$addFields:{
"spaces":{
$map:{
"input":"$spaces",
"as":"doc",
"in":{
$mergeObjects:[
"$$doc",
{
"subSpace":{
$filter:{
"input":"$$doc.subSpace",
"as":"sn",
"cond": {
"$and": [
{ "$eq": [ "$$sn._id", "5d88dfe45feb4c06a5cfb770" ] },
]
}
}
}
}
]
}
}
}
}
}
]).pretty()
Try something like this:
find({spaces._id:id})
I am trying to display unique records grouped by the particular slug passed in.
My output in postman looks like this though:
"subcats": [
{
"_id": {
"subcategory": {
"_id": "5d2b42c47b454712f4db7c37",
"name": "shirts"
}
}
}
]
when my desired output is:
"subcats": [
{
"_id": "5d2b42c47b454712f4db7c37",
"name": "shirts"
}
]
An example of a product in the database:
"_id": "5d39eff7a48e6e30ace831dc",
"name": "A colourful shirt",
"description": "A nice colourful t-shirt",
"category": {
"_id": "5d35faa67b19e32ab3dc91ec",
"name": "clothing",
"catSlug": "clothing"
},
"subcategory": {
"_id": "5d2b42c47b454712f4db7c37",
"name": "shirts",
"catSlug": "shirts"
},
"price": 19
}
I don't want that top level _id there with everything nested inside of it.
I tried using $project but then I just end up with an empty array.
const products = await Product.find({ "category.catSlug": catslug }).select({
name: 1,
description: 1,
price: 1,
category: 1
});
const subcats = await Product.aggregate([
{ $match: { "category.catSlug": catslug } },
{ $group: { _id: { subcategory: "$subcategory" } } }
{ $project: { _id: 0, name: 1 } }
]);
Promise.all([products, subcats]);
res.status(200).json({
products,
subcats
});
What I have understood from your question is you need product by category and all sub categories as a list.
Below is the aggregation:
db.getCollection('test').aggregate([
{ $match: { "category.catSlug": "clothing" } },
{ $group: { _id: '$subcategory.name', subCategory: { $first : "$subcategory" }}},
{ $group: { _id: null, subcats: { $push: {_id: "$subCategory._id", name: "$subCategory.name" }}}},
{ $project: {_id: 0, subcats: 1}}
]);
Note: You can directly push "$subcategory" but it will have catSlug inside object
Output:
{
"_id" : null,
"subcats" : [{
"_id" : "5d2b42c47b454712f4db7c37",
"name" : "shirts"
},
{
"_id" : "5d2b42c47b454712f4db7c37",
"name" : "pents"
}]
}
Hope this help!
Hi you need to assign the required data in other fields while projection then define the _id to 0 as given below
{$project:{subcat_data:'$_id.subcategory'},_id:0}
-room collection
_id: ObjectId("xxx")
bedspaces: Array
0:ObjectId("xx")
1:ObjectId("xx")
***
***
-bedspace collection
_id: ObjectId("xxxx");
number: 1
decks: Array
{
_id: ObjectId("xxx");
number: 1
status: "Vacant"
tenant: ObjectId("5c964ae7f5097e3020d1926c")
dueRent: 11
away: null
},
{
_id: ObjectId("xxx");
number: 2
status: "Vacant"
tenant: null
dueRent: 11
away: null
}
Under the decks array, is my tenant field, that have objectId, and i am going to lookup this object id, in the tenants, collection.
-tenant collection
_id: ObjectId("5c964ae7f5097e3020d1926c");
name: 'John Doe'
-expected output
/*room collection*/
_id: ObjectId("xxx")
bedspaces: [
{
_id: ObjectId("xxx")
number: 1
decks: [
{
_id: ObjectId("xxx")
number: 1
status: "Vacant"
tenant: {
name: 'John Doe'
}
dueRent: 11
away: null
},
{
_id: ObjectId("xxx");
number: 1
status: "Vacant"
tenant: null
dueRent: 11
away: null
}
]
}
]
There is also an instances, that deck array is equal to null.
In below aggregation it will only display the decks, that have tenant with object id, what i want is to display both the decks.
{
from: 'beds',
let: {bedspace: '$bedspaces'},
pipeline:[
{
$match: {
$expr: {
$in: ["$_id", "$$bedspace"]
}
}
},
{
$unwind: "$decks"
},
{
$lookup: {
from: 'tenants',
let: {tenant: "$decks.tenant"},
pipeline: [
{
$match: {
$expr: {
$eq: ["$_id", "$$tenant"]
}
}
}
],
as: "decks.tenant",
}
},
{
$unwind: "$decks.tenant"
},
{ $group: {
_id: "$_id",
decks: { $push: "$decks" },
number: {$first: "$number"}
}}
],
as: "bedspaces"
}
"how can i add condition on my second look up, to execute only if tenant is not null", so that i could retrieve both decks, or any work-around so i could achieved my desired result
Don't really have time for all the explanation right now (sorry),
Explanation
The basic issue here is that usage of $unwind is your problem and you don't need it. Use $map on the produced array content merging with the "decks" array instead. Then you can have nulls.
What you want to do here is have the values from the $lookup from your "tenants" collection transposed into the existing array within your "beds/bedspaces" collection for it's own existing "tenant" values which are the ObjectId references for the foreign collection.
The $lookup stage cannot do this by simply naming the field path within the "as" output where that path is already inside another array, and in fact the output of $lookup is always an array of results obtained from the foreign collection. You want singular values for each actual match, and of course you expect a null to be in place where nothing matches, and of course keeping the original document array of "decks" intact, but just including the foreign details where those were found.
Your code attempt seems partially aware of this point as you are using $unwind on the $lookup result on the ""tenants" collection into a "temporary array" ( but you put in in the existing path and that overwrites content ) and then attempting to "re-group" as an array through $group and $push. But the problem of course is the $lookup result does not apply to every array member within "decks", so you end up with less results than you want.
The real solution is not a "conditional $lookup", but instead to transpose the "temporary array" content from the result into the existing "decks" entries. You do this using $map to process the array members, and $arrayElemAt along with $indexOfArray in order to return the matching elements from the "temporary array" by the matching _id values to "tenant".
{ "$lookup": {
"from": Tenant.collection.name,
"let": { "tenant": "$decks.tenant" },
"pipeline": [
{ "$match": {
"$expr": { "$in": [ "$_id", "$$tenant" ] }
}}
],
"as": "tenant"
}},
{ "$addFields": {
"decks": {
"$map": {
"input": "$decks",
"in": {
"$mergeObjects": [
"$$this",
{
"tenant": {
"$cond": {
"if": {
"$eq": [
{ "$indexOfArray": ["$tenant._id", "$$this.tenant"] },
-1
]
},
"then": null,
"else": {
"$arrayElemAt": [
"$tenant",
{ "$indexOfArray": ["$tenant._id", "$$this.tenant"]}
]
}
}
}
}
Noting there we are using $mergeObjects inside the $map in order to keep the existing content of the "decks" array and only replace ( or "merge" ) an overwritten representation of "tenant" for each array member. You are using the expressive $lookup already and this like $mergeObjects is a MongoDB 3.6 feature.
Just for interest the same thing can be done by just specifying every field within the array. i.e:
"decks": {
"$map": {
"input": "$decks",
"in": {
"_id": "$$this._id",
"number": "$$this.number",
"tenant": {
// same expression
},
"__v": "$$this.__v" // just because it's mongoose
}
}
}
Much the same can be said for the $$REMOVE used in the $addFields which is also another MongoDB 3.6 feature. You can alternately just use $project and simply omit the unwanted fields:
{ "$project": {
"number": "$number",
"decks": {
"$map": { /* same expression */ }
},
"__v": "$__v"
// note we don't use the "tenant" temporary array
}}
But that's basically how it works. By taking the $lookup result and then transposing those results back into the original array within the document.
Example Listing
Also abstracting on your data from previous questions here, which is a bit better than what you posted in the question here. Runnable listing for demonstration:
const { Schema, Types: { ObjectId } } = mongoose = require('mongoose');
const uri = 'mongodb://localhost:27017/hotel';
const opts = { useNewUrlParser: true };
mongoose.set('useFindAndModify', false);
mongoose.set('useCreateIndexes', true);
mongoose.set('debug', true);
const tenantSchema = new Schema({
name: String,
age: Number
});
const deckSchema = new Schema({
number: Number,
tenant: { type: Schema.Types.ObjectId, ref: 'Tenant' }
});
const bedSchema = new Schema({
number: Number,
decks: [deckSchema]
});
const roomSchema = new Schema({
bedspaces: [{ type: Schema.Types.ObjectId, ref: 'Bed' }]
});
const Tenant = mongoose.model('Tenant', tenantSchema);
const Bed = mongoose.model('Bed', bedSchema);
const Room = mongoose.model('Room', roomSchema);
const log = data => console.log(JSON.stringify(data, undefined, 2));
(async function() {
try {
const conn = await mongoose.connect(uri, opts);
// Clean data
await Promise.all(
Object.entries(conn.models).map(([k, m]) => m.deleteMany())
);
// Insert data
let [john, jane, bilbo ] = await Tenant.insertMany([
{
_id: ObjectId("5c964ae7f5097e3020d1926c"),
name: "john doe",
age: 11
},
{
_id: ObjectId("5c964b2531bc162fdce64f15"),
name: "jane doe",
age: 12
},
{
_id: ObjectId("5caa5454494558d863513b24"),
name: "bilbo",
age: 111
}
]);
let bedspaces = await Bed.insertMany([
{
_id: ObjectId("5c98d89c6bd5fc26a4c2851b"),
number: 1,
decks: [
{
number: 1,
tenant: john
},
{
number: 1,
tenant: jane
}
]
},
{
_id: ObjectId("5c98d89f6bd5fc26a4c28522"),
number: 2,
decks: [
{
number: 2,
tenant: bilbo
},
{
number: 3
}
]
}
]);
await Room.create({ bedspaces });
// Aggregate
let results = await Room.aggregate([
{ "$lookup": {
"from": Bed.collection.name,
"let": { "bedspaces": "$bedspaces" },
"pipeline": [
{ "$match": {
"$expr": { "$in": [ "$_id", "$$bedspaces" ] }
}},
{ "$lookup": {
"from": Tenant.collection.name,
"let": { "tenant": "$decks.tenant" },
"pipeline": [
{ "$match": {
"$expr": { "$in": [ "$_id", "$$tenant" ] }
}}
],
"as": "tenant"
}},
{ "$addFields": {
"decks": {
"$map": {
"input": "$decks",
"in": {
"$mergeObjects": [
"$$this",
{
"tenant": {
"$cond": {
"if": {
"$eq": [
{ "$indexOfArray": ["$tenant._id", "$$this.tenant"] },
-1
]
},
"then": null,
"else": {
"$arrayElemAt": [
"$tenant",
{ "$indexOfArray": ["$tenant._id", "$$this.tenant"]}
]
}
}
}
}
]
}
}
},
"tenant": "$$REMOVE"
}}
],
"as": "bedspaces"
}}
]);
log(results);
} catch (e) {
console.error(e)
} finally {
mongoose.disconnect();
}
})()
Returns:
Mongoose: tenants.deleteMany({}, {})
Mongoose: beds.deleteMany({}, {})
Mongoose: rooms.deleteMany({}, {})
Mongoose: tenants.insertMany([ { _id: 5c964ae7f5097e3020d1926c, name: 'john doe', age: 11, __v: 0 }, { _id: 5c964b2531bc162fdce64f15, name: 'jane doe', age: 12, __v: 0 }, { _id: 5caa5454494558d863513b24, name: 'bilbo', age: 111, __v: 0 } ], {})
Mongoose: beds.insertMany([ { _id: 5c98d89c6bd5fc26a4c2851b, number: 1, decks: [ { _id: 5caa5af6ed3dce1c3ed72cef, number: 1, tenant: 5c964ae7f5097e3020d1926c }, { _id: 5caa5af6ed3dce1c3ed72cee, number: 1, tenant: 5c964b2531bc162fdce64f15 } ], __v: 0 }, { _id: 5c98d89f6bd5fc26a4c28522, number: 2, decks: [ { _id: 5caa5af6ed3dce1c3ed72cf2, number: 2, tenant: 5caa5454494558d863513b24 }, { _id: 5caa5af6ed3dce1c3ed72cf1, number: 3 } ], __v: 0 } ], {})
Mongoose: rooms.insertOne({ bedspaces: [ ObjectId("5c98d89c6bd5fc26a4c2851b"), ObjectId("5c98d89f6bd5fc26a4c28522") ], _id: ObjectId("5caa5af6ed3dce1c3ed72cf3"), __v: 0 })
Mongoose: rooms.aggregate([ { '$lookup': { from: 'beds', let: { bedspaces: '$bedspaces' }, pipeline: [ { '$match': { '$expr': { '$in': [ '$_id', '$$bedspaces' ] } } }, { '$lookup': { from: 'tenants', let: { tenant: '$decks.tenant' }, pipeline: [ { '$match': { '$expr': { '$in': [ '$_id', '$$tenant' ] } } } ], as: 'tenant' } }, { '$addFields': { decks: { '$map': { input: '$decks', in: { '$mergeObjects': [ '$$this', { tenant: [Object] } ] } } }, tenant: '$$REMOVE' } } ], as: 'bedspaces' } } ], {})
[
{
"_id": "5caa5af6ed3dce1c3ed72cf3",
"bedspaces": [
{
"_id": "5c98d89c6bd5fc26a4c2851b",
"number": 1,
"decks": [
{
"_id": "5caa5af6ed3dce1c3ed72cef",
"number": 1,
"tenant": {
"_id": "5c964ae7f5097e3020d1926c",
"name": "john doe",
"age": 11,
"__v": 0
}
},
{
"_id": "5caa5af6ed3dce1c3ed72cee",
"number": 1,
"tenant": {
"_id": "5c964b2531bc162fdce64f15",
"name": "jane doe",
"age": 12,
"__v": 0
}
}
],
"__v": 0
},
{
"_id": "5c98d89f6bd5fc26a4c28522",
"number": 2,
"decks": [
{
"_id": "5caa5af6ed3dce1c3ed72cf2",
"number": 2,
"tenant": {
"_id": "5caa5454494558d863513b24",
"name": "bilbo",
"age": 111,
"__v": 0
}
},
{
"_id": "5caa5af6ed3dce1c3ed72cf1",
"number": 3,
"tenant": null
}
],
"__v": 0
}
],
"__v": 0
}
]
Shows the null on the second entry of the second entry in the bedspaces array as expected.