i have the following aggregate function in my code to count how many times a value is found in the db:
let data: any = await this.dataModel.aggregate(
[
{
$match: {
field: new ObjectID(fieldID),
},
},
{
$group: {
_id: "$value",
total_for_value: { $sum: 1 },
},
},
]
);
This works correctly, however my data setup is a bit different. I have two types of value fields. Some like this:
{
"_id" : ObjectId("123"),
"value" : "MALE"
}
and some like this:
{
"_id" : ObjectId("456"),
"value" : {
"value" : "MALE",
}
}
Is there a way to group the ones where the _id and the _id.value are the same? At the moment it counts them separately.
db.collection.aggregate([
{
"$addFields": {
"key2": {
"$cond": {
"if": {
$and: [
{
"$eq": [
{
"$type": "$key"
},
"object"
]
}
]
},
"then": "$key.value",
"else": "$key"
}
}
}
},
{
"$group": {
"_id": "$key2",
"data": {
$push: "$$ROOT"
}
}
}
])
This would do the job if _id.value is an object.
Playground
Related
Suppose I have data in bookOrder as:
{
"_id" : ObjectId("615fc295257d6d7cf57a39fe"),
"orderId" : "2001",
"itemId" : [
"615fc232257d6d7cf57a39d4",
"615fc251257d6d7cf57a39e0"
],
"Discount" : 10
}
Item data as:
{
"_id" : ObjectId("615fc232257d6d7cf57a39d4"),
"itemId" : "1001",
"Price" : 10.21
}
{
"_id" : ObjectId("615fc251257d6d7cf57a39e0"),
"itemId" : "1002",
"Price" : 100
}
I want to calculate the total price of order after discount,
i.e. total price as : 100+10.21-10 = 100.21
For this I tried as:
const data = await db.order.aggregate(
[
{
"$match": {
"orderId": orderId
}
},
{
"$lookup": {
"from": "item",
let: {
eid: "$itemId"
},
pipeline: [
{
"$match": {
$expr: {
$in: [
"$_id",
"$$eid"
]
}
}
},
],
"as": "items"
}
},
{
"$unwind": {
path: "$items"
}
},
]
)
So, I get the value as:
{
"orderId" : "2001",
"Discount":10,
"itemId":[{
"itemId" : "1001",
"Price" : 10.21
},
"itemId" : "1002",
"Price" : 100
]}
}
SO instead of having to loop over the itemId price and get total sun, and then subtracting from the discount price of order can we do all these calculations of db itself.
Is there any way that I can query the total price from DB only instead of having to fetch data and applying any loop and then calculating the total price?
Please let me know if anyone needs any further explanation from my side.
use sum
aggregate
db.orders.aggregate([
{
"$match": {
"orderId": "2001"
}
},
{
"$lookup": {
"from": "items",
"localField": "itemId",
"foreignField": "_id",
"as": "items"
}
},
{
"$project": {
"orderId": 1,
"total": {
$subtract: [
{
"$sum": "$items.Price"
},
"$Discount"
]
}
}
}
])
mongoplayground
You can do this in a couple of ways, here is the most straight forward one using $map and some math operators.
db.order.aggregate([
{
"$match": {
"orderId": "2001"
}
},
{
"$lookup": {
"from": "item",
let: {
eid: "$itemId"
},
pipeline: [
{
"$match": {
$expr: {
$in: [
"$_id",
"$$eid"
]
}
}
},
],
"as": "items"
}
},
{
$project: {
orderId: 1,
finalSum: {
$subtract: [
{
$sum: {
$map: {
input: "$items",
in: "$$this.Price"
}
}
},
"$Discount"
]
}
}
}
])
Mongo Playground
I'm trying to get data from 2 collections, and return one array with merge data of both collection.
The best solution for me was :
const bothValues = await ValueA.aggregate([
{ $unionWith: { coll: 'valueB' } },
{ $sort: { rank: -1, _id: -1 } },
{
$match: {
isAvailable: true,
},
},
{ $skip: skip },
{ $limit: 30 },
]);
which work perfectly. But.. $unionWith was not implemented my MongoDB version (4.0.X) so I can't use it.
const bothValues = await ValueA.aggregate(
[
{ $limit: 1 },
{
$lookup: {
from: 'valueB',
pipeline: [{ $limit: 15 }],
as: 'valueB',
},
},
{
$lookup: {
from: 'ValueA',
pipeline: [{ $limit: 15 }, { $sort: { rank: -1, _id: -1 } }],
as: 'ValueA',
},
},
{
$project:
{
Union: { $concatArrays: ['$valueB', '$ValueA'] },
},
},
{ $unwind: '$Union' },
{ $replaceRoot: { newRoot: '$Union' } },
],
);
but now, I got 2 problems :
I can't use a $skip, which is important, where use it ?
How to use $match ?
Thanks
Query
your query made with some changes to work like the first query
match in both pipelines, sort in both, (limit limitN+skipN)
(this way we make sure that we always have enough documents even if all are taken from valueA or valueB)
Take sorted 70 from each, so in all ways we will have the 70 needed in the final sort/skip/limit after the union.
concat,unwind,replace-root like in your query
sort again (to sort the union now), skip, limit
no matter we always have enough documents to skip
this example query is made for skip=40 and limit=30 so in the first 2 pipelines we limit=70
db.ValueA.aggregate([
{
"$limit": 1
},
{
"$lookup": {
"from": "valueB",
"pipeline": [
{
"$match": {
"isAvailable": true
}
},
{
"$sort": {
"rank": -1,
"_id": -1
}
},
{
"$limit": 70
}
],
"as": "valueB"
}
},
{
"$lookup": {
"from": "valueA",
"pipeline": [
{
"$match": {
"isAvailable": true
}
},
{
"$sort": {
"rank": -1,
"_id": -1
}
},
{
"$limit": 70
}
],
"as": "valueA"
}
},
{
"$project": {
"union": {
"$concatArrays": [
"$valueA",
"$valueB"
]
}
}
},
{
"$unwind": {
"path": "$union"
}
},
{
"$replaceRoot": {
"newRoot": "$union"
}
},
{
"$sort": {
"rank": -1,
"_id": -1
}
},
{
"$skip": 40
},
{
"$limit": 30
}
])
I have this data structure:
{
"_id": "5ebd08794bcc8d2fd893f4a7",
"username": "johan#gmail.com",
"password": "123",
"decks": [{
"cards": [{
"_id": "5ebd08794bcc8d2fd893f4a9",
"planeetnaam": "Venus",
"kleur": "Grijs"
},
{
"_id": "5ebd08794bcc8d2fd893f4aa",
"planeetnaam": "Neptunus",
"kleur": "Paars"
}
],
"_id": "5ebd08794bcc8d2fd893f4a8",
"name": "Planeten"
},
{
"cards": [{
"_id": "5ebd08794bcc8d2fd893f4ac",
"diernaam": "Hond",
"poten": "4"
},
{
"_id": "5ebd08794bcc8d2fd893f4ad",
"diernaam": "Kangoeroe",
"poten": "2"
}
],
"_id": "5ebd08794bcc8d2fd893f4ab",
"name": "Dieren"
}
],
"__v": 0
}
Now i want to add a new property to all the cards in deck with deckname: "Planeten". How do i do this with a mongoose query?
The cards array of deck "Planeten" should look like this after the query
"cards": [{
"_id": "5ebd08794bcc8d2fd893f4a9",
"planeetnaam": "Venus",
"kleur": "Grijs",
"newProp": null
},
{
"_id": "5ebd08794bcc8d2fd893f4aa",
"planeetnaam": "Neptunus",
"kleur": "Paars",
"newProp": null
}
],
EDIT:
This works in Robo3T:
db.getCollection('users').findOneAndUpdate(
{ '_id': ObjectId("5eba9ee0abfaf237f81fb104") },
{ $set: { 'decks.$[deck].cards.$[].newProp': null } },
{ arrayFilters: [{ 'deck._id': ObjectId("5eba9ee0abfaf237f81fb108") } ] }
)
But the server query doesnt edit any data:
User.findOneAndUpdate(
{ '_id': req.session.userid },
{ $set: { 'decks.$[deck].cards.$[].newProp': null } },
{ arrayFilters: [{ 'deck._id': req.params.deckid } ] }, function(err, user){
res.send('test');
})
Thanks in advance
you can use array update operators
the query may look something like that
db.collection.updateOne(
{ _id: <ObjectId> }, // the filter part
{ $set: { 'decks.$[deck].cards.$[].newProp': null } },
{ arrayFilters: [{ 'deck.name': 'Planeten' }] }
)
$[deck] refers to each element in the decks array
$[] is used to update all the elements in the cards array
your function may look something like that
User.updateOne(
{ '_id': req.session.userid },
{ $set: { 'decks.$[deck].cards.$[].newProp': null } },
{ arrayFilters: [{ 'deck.name': 'Planeten' }] })
.then(function (user) {
if (!user) {
res.status(404).send('Er ging helaas iets fout')
} else {
res.status(201).send("Card is toegevoegd");
}
})
hope it helps
My documents looks like this.
{
"_id" : ObjectId("572c4bffd073dd581edae045"),
"name" : "What's New in PHP 7",
"description" : "PHP 7 is the first new major version number of PHP since 2004. This course shows what's new, and what's changed.",
"difficulty_level" : "Beginner",
"type" : "Normal",
"tagged_skills" : [
{
"_id" : "5714e894e09a0f7d804b2254",
"name" : "PHP"
}
],
"created_at" : 1462520831.649,
"updated_at" : 1468233074.243 }
Is it possible to get recent 5 documents and total count in a single query.
I am using two queries for this requirement as given below.
db.course.find().sort({created_at:-1}).limit(5)
db.course.count()
This is a perfect job for the aggregation framework.
db.course.aggregate(
[
{ "$sort": { "created_at": -1 }},
{ "$group": {
"_id": null,
"docs": { "$push": "$$ROOT" },
"count": { "$sum": 1 }
}},
{ "$project": { "_id": 0, "count": 1, "docs": { "$slice": [ "$docs", 5 ] } }}
]
)
If your MongoDB server doesn't support $slice then you need to use the ugly and inefficient approach.
db.course.aggregate(
[
{ "$sort": { "created_at": -1 }},
{ "$group": {
"_id": null,
"docs": { "$push": "$$ROOT" },
"count": { "$sum": 1 }
}},
{ "$unwind": "$docs" },
{ "$limit": 5 }
]
)
You can implement this easily with $facet
myCollection.aggregate([
{
$facet: {
count: [{ $count: "value" }],
data: [{ $sort: { _id: -1 } }, { $skip: skip }, { $limit: limit }]
}
},
{ $unwind: "$count" },
{ $set: { count: "$count.value" } }
])
the return result will be like:
[
{
"count": 234,
"data": [
// ...
]
}
]
#styvane I tested in person, this query is even less efficient than twice queries.
// get count
db.course.aggregate([{$match:{}}, {$count: "count"}]);
// get docs
db.course.aggregate(
[
{$match:{}},
{ "$sort": { "created_at": -1 }},
{"$skip": offset},
{"$limit": limit}
]
)
No, there is no other way. Two queries - one for count - one with limit.
Assuming I have a schema that looks something like this:
{
field: [{
subDoc: ObjectId,
...
}],
...
}
and I have some list of ObjectIds (user input), how would I get a count of those specific ObjectIds? For exmaple, if I have data like this:
[
{field: [ {subDoc: 123}, {subDoc: 234} ]},
{field: [ {subDoc: 234}, {subDoc: 345} ]},
{field: [ {subDoc: 123}, {subDoc: 345}, {subDoc: 456} ]}
]
and the list of ids given by the user is 123, 234, 345, I need to get a count the given ids, so a result approximating this:
{
123: 2,
234: 2,
345: 2
}
What would be the best way to go about this?
The aggregation framework itself if not going to dynamically name keys the way you have presented as a proposed output, and that probably is a good thing really. But you can probably just do a query like this:
db.collection.aggregate([
// Match documents that contain the elements
{ "$match": {
"field.subDoc": { "$in": [123,234,345] }
}},
// De-normalize the array field content
{ "$unwind": "$field" },
// Match just the elements you want
{ "$match": {
"field.subDoc": { "$in": [123,234,345] }
}},
// Count by the element as a key
{ "$group": {
"_id": "$field.subDoc",
"count": { "$sum": 1 }
}}
])
That gives you output like this:
{ "_id" : 345, "count" : 2 }
{ "_id" : 234, "count" : 2 }
{ "_id" : 123, "count" : 2 }
But if you really want to go nuts on this, you are specifying the "keys" that you want as part of your query, so you could form a pipeline like this:
db.collection.aggregate([
{ "$match": {
"field.subDoc": { "$in": [123,234,345] }
}},
{ "$unwind": "$field" },
{ "$match": {
"field.subDoc": { "$in": [123,234,345] }
}},
{ "$group": {
"_id": "$field.subDoc",
"count": { "$sum": 1 }
}},
{ "$group": {
"_id": null,
"123": {
"$max": {
"$cond": [
{ "$eq": [ "$_id", 123 ] },
"$count",
0
]
}
},
"234": {
"$max": {
"$cond": [
{ "$eq": [ "$_id", 234 ] },
"$count",
0
]
}
},
"345": {
"$max": {
"$cond": [
{ "$eq": [ "$_id", 345 ] },
"$count",
0
]
}
}
}}
])
Which is a relatively simple thing to construct that last stage in code by just processing the list of arguments:
var list = [123,234,345];
var group2 = { "$group": { "_id": null } };
list.forEach(function(id) {
group2["$group"][id] = {
"$max": {
"$cond": [
{ "$eq": [ "$_id", id ] },
"$count",
0
]
}
};
});
And that comes out more or less how you want it.
{
"_id" : null,
"123" : 2,
"234" : 2,
"345" : 2
}
Not exactly what you're asking for but it can give you an idea:
db.test.aggregate([
{
$unwind: '$field'
},
{
$group: {
_id: {
subDoc: '$field.subDoc'
},
count: {
$sum: 1
}
}
},
{
$project: {
subDoc: '$subDoc.subDoc',
count: '$count'
}
}
]);
Output:
{
"result": [
{
"_id": {
"subDoc": 456
},
"count": 1
},
{
"_id": {
"subDoc": 345
},
"count": 2
},
{
"_id": {
"subDoc": 234
},
"count": 2
},
{
"_id": {
"subDoc": 123
},
"count": 2
}
],
"ok": 1
}