I have an mongoDB objetc like :
[
{
"items": [
{
"title": "hello",
"options": [
{
"value": "A",
"image": "img1",
"des": "des1"
},
{
"value": "B",
"image": "img2",
"des": "des2"
},
]
}
]
}
]
When I retrieve data from the collection, I want to retrieve only value key from the options of the items array.
Output should look like :
{
"items":[
{
"options" :[
{ "value" :"A" },
{ "value" :"B" },
]
}
]
}
How can i do this?
You can do it like this:
db.collection.find({}, { "items.options.value": 1})
Here is the working example: https://mongoplayground.net/p/FqDaQ7Q-y-Y
Or you can do it like this:
db.collection.aggregate([
{
"$project": {
"items.options.value": 1
}
}
])
Here is the working example: https://mongoplayground.net/p/jPFYtXYBvpI
Related
I'm working in MongoDB and getting stuck at one aggregation case. Let me show you my collection.
First collection (data):
[
{
"_id": "8e7b3fa0-4230-448c-8f70-1d7300632834",
"data": [
{
"animal" : "7d44251a-b308-4deb-875a-33ef0a69fe2b",
"place": "Chennai"
},
{
"animal" : "fcfdd527-5885-48b0-a91f-03f72f78528f",
"place": "Kolkata"
}
]
}
]
Second collection (Animal):
[
{
"_id": "7d44251a-b308-4deb-875a-33ef0a69fe2b",
"name": "Dog"
},
{
"_id": "7d44251a-b308-4deb-875a-33ef0a69fe2b",
"name": "Cat"
}
]
I'm using this query:
db.data.aggregate([
{
"$lookup": {
"from": "animal",
"localField": "data.animal",
"foreignField": "_id",
"as": "doc"
}
},
{
"$unwind": "$doc"
},
{
"$project": {
"_id": 1,
"data.animal": "$doc.name",
"data.place": 1
}
}
])
and it result me this
[
{
"_id": "8e7b3fa0-4230-448c-8f70-1d7300632834",
"data": [
{
"animal": "Dog",
"place": "Chennai"
},
{
"animal": "Dog",
"place": "Kolkata"
}
]
},
{
"_id": "8e7b3fa0-4230-448c-8f70-1d7300632834",
"data": [
{
"animal": "Cat",
"place": "Chennai"
},
{
"animal": "Cat",
"place": "Kolkata"
}
]
}
]
Where I'm expecting like this
[
{
"_id": "8e7b3fa0-4230-448c-8f70-1d7300632834",
"data": [
{
"animal": "Dog",
"place": "Chennai"
},
{
"animal": "Cat",
"place": "Kolkata"
}
]
}
]
Mongo Playground
Also sharing this question in Mongo playgroud. Thanks in advance!!
Solution 1
$unset - Deconstruct the data array into multiple documents.
$lookup - Perform join with animal collection.
$project - Decorate the output document. For data.animal field, get the first value via $first.
$group - Group by _id. Push the data document into the data array.
db.data.aggregate([
{
"$unwind": "$data"
},
{
"$lookup": {
"from": "animal",
"localField": "data.animal",
"foreignField": "_id",
"as": "doc"
}
},
{
"$project": {
"_id": 1,
"data.animal": {
$first: "$doc.name"
},
"data.place": 1
}
},
{
$group: {
_id: "$_id",
data: {
$push: "$data"
}
}
}
])
Demo Solution 1 # Mongo Playground
Solution 2
$lookup
$set - Set data field.
2.1. $map - Iterate the data array and returns a new array.
2.1.1. $mergeObjects - Merge current iterated document with place field and the document from 2.1.1.1.
2.1.1.1. $first - Get the first document from the filtered doc arrays by matching the ids via $filter.
$unset - Remove _id and animals._id fields.
db.data.aggregate([
{
"$lookup": {
"from": "animal",
"localField": "data.animal",
"foreignField": "_id",
"as": "doc"
}
},
{
$set: {
data: {
$map: {
input: "$data",
as: "data",
in: {
$mergeObjects: [
{
place: "$$data.place"
},
{
$first: {
$filter: {
input: "$doc",
cond: {
$eq: [
"$$this._id",
"$$data.animal"
]
}
}
}
}
]
}
}
}
}
},
{
$unset: [
"doc",
"data._id"
]
}
])
Demo Solution 2 # Mongo Playground
What I have is a collection of documents in MongoDB that have the structure something like this
[
{
"userid": "user1",
"addresses": [
{
"type": "abc",
"street": "xyz"
},
{
"type": "def",
"street": "www"
},
{
"type": "hhh",
"street": "mmm"
},
]
},
{
"userid": "user2",
"addresses": [
{
"type": "abc",
"street": "ccc"
},
{
"type": "def",
"street": "zzz"
},
{
"type": "hhh",
"street": "yyy"
},
]
}
]
If I can give the "type" and "userid", how can I get the result as
[
{
"userid": "user2",
"type": "abc",
"street": "ccc",
}
]
It would also be great even if I can get the "street" only as the result. The only constraint is I need to get it in the root element itself and not inside an array
Something like this:
db.collection.aggregate([
{
$match: {
userid: "user1" , "address.type":"abc"
}
},
{
$project: {
userid: 1,
address: {
$filter: {
input: "$addresses",
as: "a",
cond: {
$eq: [
"$$a.type",
"abc"
]
}
}
}
}
},
{
$unwind: "$address"
},
{
$project: {
userid: 1,
street: "$address.street",
_id: 0
}
}
])
explained:
Filter only documents with the userid & addresess.type you need
Project/Filter only the addresses elements with the needed type
unwind the address array
project only the needed elements as requested
For best results create index on the { userid:1 } field or compound index on { userid:1 , address.type:1 } fields
playground
You should be able to use unwind, match and project as shown below:
db.collection.aggregate([
{
"$unwind": "$addresses"
},
{
"$match": {
"addresses.type": "abc",
"userid": "user1"
}
},
{
"$project": {
"_id": 0,
"street": "$addresses.street"
}
}
])
You can also duplicate the match step as the first step to reduce the number of documents to unwind.
Here is the playground link.
There is a similar question/answer here.
I have a doc like this
{
"_id" : "oidfi",
"users": [
{
"_id": "q",
"tags": ["a", "b", "c"],
"age": 20
},
{
"_id": "q",
"tags": ["x", "y", "z"],
"age": 30
}
],
"type": "repo"
}
I want to filter the users array with several fields ( I'm able to do that with the below query )
{
"$match": {
"$and": [
{
"_id": "a506f8af6f510f616bea14715276d474d2b363f0aef10443cc0f11559b139147"
}
]
}
},
{
"$project": {
"users": {
"$filter": {
"input": "$users",
"as": "users",
"cond": {
"$and": [
{
"$gte": [
"$$user.age",
15
]
}
]
}
}
}
}
}
]
is there a way for me to add condition where I give a list of tags items and get the users who are matching at least one item from their tags array
$$user.tags.containsAny(["a", "x"])
Thanks
You can do the followings in an aggregation pipeline:
$setIntersection to find out the intersection of the users.tags array and your input array i.e. ["a", "x"] in your example
$size to find the size of array in step 1
$match by the size of step 2 larger than 0
"anyTagsMatched": {
$gt: [
{
$size: {
"$setIntersection": [
"$users.tags",
[
"a",
"x"
]
]
}
},
0
]
}
Here is the Mongo playground for your reference.
You may have like following
db.collection.aggregate([
{
"$project": {
"users": {
"$filter": {
"input": "$users",
"cond": {
"$and": [
{ "$gte": [ "$$this.age", 15 ] },
{
$gt: [
{
$size: {
"$setIntersection": [
"$$this.tags",
[ "a", "x" ]
]
}
},
0
]
}
]
}
}
}
}
}
])
Working Mongo playground
I've been trying to make a set of strings < or arrays > but my main issue is that I can't use $unwind because of the other data.
To make it more clear I'll show an example:
This is how part of my documents look like:
{
"key": [
"a",
"b",
"c"
]
},
{
"key": [
"b",
"d"
]
},
{
"key": [
"e"
]
}
And I want to get an array like this:
{
"keys": [
"a",
"b",
"c",
"d",
"e"
]
}
or this:
{
"keys": [
["a"],
["b"],
["c"],
["d"],
["e"]
]
}
I just need unique values in there.
It would be so easy if I could use $unwind and then $addToSet. But as I said before I can't because of the other data that I need.
I was trying to use $cond inside the $addToSet but I don't know how to iterate through an array.
This pipeline doesn't work ->
db.collection.aggregate([
{
"$group": {
"_id": null,
"keys": {
"$addToSet": {
"$concatArrays": [
"$key",
"$this"
]
}
},
}
}
])
Maybe something like this:
{
"$group": {
"_id": null,
"keys": {
"$addToSet": {
"$cond": {
if: {
"$gt": [
{"$size": "$key"},
1
]
},
then: "<SPLIT THE ARRAY IN THE AMOUNT OF ELEMENTS>",
else: "$key"
}
}
}
}
}
I tried this but it doesn't work either.
db.collection.aggregate([
{
"$project": {
"keys": {
"$map": {
"input": {
"$range": [
0,
{
"$size": "$key"
},
1
]
},
as: "index",
in: {
$slice: [
"$key",
"$$index",
1
]
}
}
}
}
},
{
"$group": {
"_id": null,
"keys": {
"$addToSet": {
"$concatArrays": [
"$keys"
]
}
},
}
}
])
Here is my code snippet: https://mongoplayground.net/p/sMENXyrbQgI
Could someone please guide me! I'll appreciate it so much.
So the idea is to use $setUnion along with $reduce to pick unique values from the array:
Solution in MongoPlayground
Try this query:
db.collection.aggregate([
{
$group: {
_id: null,
"keys": { $push: "$key" }
}
},
{
$addFields: {
"keys": {
$reduce: {
input: "$keys",
initialValue: [],
in: {
$setUnion: ["$$value", "$$this"]
}
}
}
}
}
])
Output:
{
"_id" : null,
"keys" : [
"a",
"b",
"c",
"d",
"e"
]
}
Test data in collection:
[
{
"key": [
"a",
"b",
"c"
]
},
{
"key": [
"b",
"d",
"a",
]
},
{
"key": [
"e",
"b"
]
}
]
i need to take child array in this json . i tried too many ways, how can i take kindC -> name . Plz help !!
Full map:
[
{
"direction": {
"book": "A",
"note": "B"
},
"prize": {
"kindA": [],
"kindB": [],
"kindC": [{
"name": "Target#1",
"_id": "32131"
}]
},
]
}
Just access the prize object
console.log(data[0].prize.kindC);
if you need to access the 1st object
console.log(data[0].prize.kindC[0].name);
DEMO
var data = [
{
"direction": {
"book": "A",
"note": "B"
},
"prize": {
"kindA": [],
"kindB": [],
"kindC": [
{
"name": "Target#1",
"_id": "32131"
}
]
}
}
];
console.log(data[0].prize.kindC[0].name);
DEMO
var jsonObj = [
{
"direction": {
"book": "A",
"note": "B"
},
"prize": {
"kindA": [],
"kindB": [],
"kindC": [
{
"name": "Target#1",
"_id": "32131"
}
]
}
}
];
console.log(jsonObj[0].prize.kindC[0].name);