I'm new on mongodb. so I try design the schema for my collection is like below
all the ObjectId is not real
stockIn documents
{
serial:"stk0001",
date:'2021-06-11',
productInTransation:[
{
_id:"60ae220b066b8d9861118cb1",
productId:"60ae220b066b8d9861118cb2"
qty:2
},
{
_id:"60ae220b066b8d9861118cb1",
productId:"60ae220b066b8d9861118cb1",
qty:2
}
]
}
and I have a products collection
[
{
_id:"60ae220b066b8d9861118cb5",
name:"sepatu"
},
{
_id:"60ae220b066b8d9861118cb4",
name:"sendal"
}
]
so what I expect from those documents is just like below
{
serial:"stk0001",
date:'2021-06-11',
productInTransation:[
{
_id:"60ae220b066b8d9861118cb1",
productId:"60ae220b066b8d9861118cb2"
qty:2,
product:
{
_id:"60ae220b066b8d9861118cb5",
name:"sepatu"
},
},
{
_id:"60ae220b066b8d9861118cb1",
productId:"60ae220b066b8d9861118cb1",
qty:2,
product:
{
_id:"60ae220b066b8d9861118cb4",
name:"sendal"
}
}
]
}
this collection is just simplified from the real case.
and the problem I don't know how to do a query on mongodb, so the output will same as the expected. thank's for any help
You can use $lookup
$unwind to deconstruct the array
$lookup to join collections
$ifNull to make sure this doesn't give any NPE when we take from first element from the joined array using $arrayElemAt
$group to reconstruct the array
Here is the code
db.stockIn.aggregate([
{ $unwind: "$productInTransation" },
{
"$lookup": {
"from": "products",
"localField": "productInTransation.productId",
"foreignField": "_id",
"as": "productInTransation.product"
}
},
{
"$addFields": {
"productInTransation.product": {
"$ifNull": [ { "$arrayElemAt": [ "$productInTransation.product", 0 ] }, [] ]
}
}
},
{
"$group": {
"_id": "$_id",
"date": { "$first": "$date" },
"serial": { "$first": "$serial" },
"productInTransation": { $push: "$productInTransation" }
}
}
])
Working Mongo playground
Related
I want to retrieve a value from an object with a dynamic key
[
{
"_id": 1,
"item": "sweatshirt",
"price": {
"INR": 45.99
},
"currency": 'INR'
}
]
db.collection.aggregate([
{
"$project": {
"pricenew": "$price.currency"
}
}
])
If I do price.INR it will work fine but here I have currency dynamic, so I want something like price.currency but here currency is coming like "INR" and it gives no data.
I really appreciate any help you can provide.
You need to convert the price object to an array using $objectToArray, filter it and then convert it back, like so:
db.collection.aggregate([
{
$replaceRoot: {
newRoot: {
"$mergeObjects": [
{
"$arrayToObject": {
$map: {
input: {
$filter: {
input: {
"$objectToArray": "$price"
},
cond: {
$eq: [
"$$this.k",
"$currency"
]
}
}
},
in: {
k: "pricenew",
v: "$$this.v"
}
}
}
},
{
_id: "$_id"
}
]
}
}
}
])
Mongo Playground
I have a questions collection with _id and name and other fields(..), and a tests collection with _id, name and array of questions.
I'm trying to get all the questions with their fields and adding a field "usedIn" which counts the number of tests that the specific questions is present in.
questions = await Question.aggregate([
/*{
"$match": {
params
}
},*/
{
"$lookup": {
"from": "tests",
"let": {"questionId": "$_id"},
pipeline: [
{
"$match": {
"$expr": {
"$in": ["$$questionId", "$questions"],
},
},
},
],
as: "tests"
}
},
{
"$addFields": {
"usedIn": {
"$size": "tests"
}
}
},
{
"$project": fieldsObject
},
])
This code is giving me this error:
Error: Failed to optimize pipeline :: caused by :: The argument to $size must be an array, but was of type: string
What Am I doing wrong ?
You can do it like this:
db.questions.aggregate([
{
"$lookup": {
"from": "tests",
"localField": "_id",
"foreignField": "questions",
"as": "usedIn"
}
},
{
"$project": {
"usedIn": {
"$size": "$usedIn"
},
"name": 1
}
}
])
Working example
I'm new in mongodb and try small project and document are design just like below
products
[
{
_id:ObjectId('60d87d6fafd7a1377c03b2e6'),
productName:"noodles instant",
description:"lorem ipsum ... ... ...."
},
{
_id:ObjectId('60d87d6fafd7a1377c03b2e7'),
productName:"Sandal",
description:"lorem ipsum ... ... ...."
}
]
and my transaction document has structure is just like below
transactions
[
{
_id:ObjectId('60d8781031308dbf565eaaa8'),
trasactionSerial:"TRS20210000001",
transactionDate:2021-06-27T13:30:23.369+00:00,
productInTransactions:[
{
_id:ObjectId('60d8781031308dbf565eaab9'),
productId:ObjectId('60d87d6fafd7a1377c03b2e6'),
qty:1500
},
{
_id:ObjectId('60d8781031308dbf565eaa47'),
productId:ObjectId('60d87d6fafd7a1377c03b2e7'),
qty:200
}
]
},
{
_id:ObjectId('60d8781031308dbf565eaab7'),
trasactionSerial:"TRS20210000002",
transactionDate:2021-06-27T13:32:23.369+00:00,
productInTransactions:[
{
_id:ObjectId('60d8781031308dbf565eaab9'),
productId:ObjectId('60d87d6fafd7a1377c03b2e6'),
qty:100
},
{
_id:ObjectId('60d8781031308dbf565eaa47'),
productId:ObjectId('60d87d6fafd7a1377c03b2e7'),
qty:300
}
]
}
]
from the transaction I hope will get some result like below from the same date in transactionDate field
result
[
{
_id:ObjectId('60d87d6fafd7a1377c03b2e6'),
productName:"noodles instant",
qtyInTransaction:1600
},
{
_id:ObjectId('60d87d6fafd7a1377c03b2e7'),
productName:"Sandal",
qtyInTransaction:500
},
]
sorry maybe my English is poor to elaborate it
thanks for any feedback and your help
Use the $lookup stage which has $group in its pipeline option.
db.products.aggregate([
{
"$lookup": {
"from": "transactions",
"let": {
"pId": "$_id"
},
"pipeline": [
{
"$unwind": "$productInTransactions"
},
{
"$match": {
"$expr": {
"$eq": [
"$productInTransactions.productId",
"$$pId"
]
},
},
},
{
"$group": {
"_id": "$$pId",
"qtyInTransaction": {
"$sum": "$productInTransactions.qty"
}
},
},
],
"as": "matchedTransactions"
}
},
{
"$project": {
"_id": 1,
"description": 1,
"qtyInTransaction": {
"$arrayElemAt": [
"$matchedTransactions.qtyInTransaction",
0
]
}
},
},
])
Mongo Playground Sample Execution
I was wondering if it was possible to destructure arrays while I am still in the MongoDB aggregation pipeline which would make my code alot neater.
For example, I have the following aggregation pipeline.
await User.aggregate([
{ $match: { _id: userID } },
{
$project: { chatLogs: 1, username: 1, profilePicURL: 1 },
},
{ $unwind: "$chatLogs" },
{
$lookup: {
from: "users",
let: { recipientID: "$chatLogs.recipientID" },
pipeline: [
{
$match: { $expr: { $eq: ["$_id", "$$recipientID"] } },
},
{ $project: { profilePicURL: 1 } },
],
as: "chatLogs.recipientID",
},
},
]);
This gives the following results when queried:
{
"_id": "5f2ffb54eea9c2180a732afa",
"username": "joe",
"profilePicURL": "/images/profile/default_profile.png",
"chatLogs": {
"recipientID": [
{
"_id": "5f2faf5ad18a76073729f475",
"profilePicURL": "/images/profile/default_profile.png"
}
],
"chat": "5f30b6c3d117441c2abda1ba"
}
}
In my case, because "recipientID" represents a default MongoDB id, it will always be unique. Hence I would prefer the following, where the resulting recipientID field is no longer a meaningless array
Desired results:
{
"_id": "5f2ffb54eea9c2180a732afa",
"username": "joe",
"profilePicURL": "/images/profile/default_profile.png",
"chatLogs": {
"recipientID": {
"_id": "5f2faf5ad18a76073729f475",
"profilePicURL": "/images/profile/default_profile.png"
}
"chat": "5f30b6c3d117441c2abda1ba"
}
}
You can deconstruct recipientID array using $unwind in last pipeline,
await User.aggregate([
... // your all pipelines
// add this line
{ $unwind: "$chatLogs.recipientID" }
]);
What I'm trying to achieve with a find query is to only include "someArray"s if it's inner array is not empty. For example the JSON below:
{
"document": "some document",
"someArray": [
{
"innerArray": [
"not empty"
]
},
{
"innerArray": [
[] //empty
]
}
]
}
Would return this:
{
"document": "some document",
"someArray": [
{
"innerArray": [
"not empty"
]
}
]
}
I'm using the following find:
Visit.find({'someArray.innerArray.0': {$exists: true}}, function(err, data){});
However, this returns all data.
Have also tried:
Visit.find({}, {'someArray.innerArray': {$gt: 0}}, function(err, data) {});
But this returns nothing
Any ideas on how to approach this?
Cheers
The general case here to check for a non-empty array is to check to see if the "first" element actually exists. For single matches you can project with the positional $ operator:
Vist.find(
{ "someArray.innerArray.0": { "$exists": true } },
{ "document": 1,"someArray.$": 1},
function(err,data) {
}
);
If you need more than a single match or have arrays nested more deeply than this, then the aggregation framework is what you need to handle the harder projection and/or "filter" the array results for more than one match:
Visit.aggregate(
[
// Match documents that "contain" the match
{ "$match": {
"someArray.innerArray.0": { "$exists": true }
}},
// Unwind the array documents
{ "$unwind": "$someArray" },
// Match the array documents
{ "$match": {
"someArray.innerArray.0": { "$exists": true }
}},
// Group back to form
{ "$group": {
"_id": "$_id",
"document": { "$first": "$document" },
"someArray": { "$push": "$someArray" }
}}
],function(err,data) {
}
)
Worth noting here that you are calling this "empty" but in fact is is not, as it actually contains another empty array. You probably don't want to do that with real data, but if you have then you would need to filter like this:
Visit.aggregate(
[
{ "$match": {
"someArray": { "$elemMatch": { "innerArray.0": { "$ne": [] } } }
}},
{ "$unwind": "$someArray" },
{ "$match": {
"someArray.innerArray.0": { "$ne": [] }
}},
{ "$group": {
"_id": "$_id",
"document": { "$first": "$document" },
"someArray": { "$push": "$someArray" }
}}
],function(err,data) {
}
);