I am trying to update my mongo database which has following structure.
{
"_id" : ObjectId("5a64d076bfd103df081967ae"),
"values" : [
{
"date" : "2018-01-22",
"Price" : "1289.4075"
},
{
"date" : "2018-01-22",
"Price" : "1289.4075"
},
{
"date" : "2015-05-18",
"Price" : 1289.41
}
],
"Code" : 123456,
"schemeStatus" : "Inactive"
}
I want to compare first 2 array element's date value i.e values[0].date and values[1].date. If both matches then I want to delete values[0] so that there will be only 1 entry with that date.
You can use aggregation framework's pipeline with $out as a last stage to update your collection
db.collection.aggregate([
{
$addFields: {
sameDate: {
$let: {
vars: {
fst: { $arrayElemAt: [ "$values", 0 ] },
snd: { $arrayElemAt: [ "$values", 1 ] }
},
in: { $cond: { if: { $eq: [ "$$fst.date", "$$snd.date" ] }, then: 1, else: 0 } }
}
}
}
},
{
$project: {
_id: 1,
values : { $cond: { if: { $eq: [ "$sameDate", 0 ] }, then: "$values", else: { $slice: [ "$values", 1, { $size: "$values" } ] } } },
Code: 1,
schemeStatus: 1
}
},
{ $out: "collection" }
])
Some more important operators used here:
$cond to handle if-else logic
$let to define some helper variables
$arrayElemAt to get first and second element
$slice to pop first element
Related
Below is the document which has an array name datum and I want to filter the records based on group by year and filter by the types and max date.
{
"_id" : ObjectId("5fce46ca6ac9808276dfeb8c"),
"year" : 2018,
"datum" : [
{
"Type" : "1",
"Amount" : NumberDecimal("100"),
"Date" : ISODate("2018-05-30T00:46:12.784Z")
},
{
"Type" : "1",
"Amount" : NumberDecimal("300"),
"Date" : ISODate("2023-05-30T00:46:12.784Z")
},
{
"Type" : "2",
"Amount" : NumberDecimal("340"),
"Date" : ISODate("2025-05-30T00:46:12.784Z")
},
{
"Type" : "3",
"Amount" : NumberDecimal("300"),
"Date" : ISODate("2021-05-30T00:46:12.784Z")
}
]
}
The aggregate Query I tried.
[{$group: {
_id :"$year",
RecentValue :
{
$sum: {
$reduce: {
input: '$datum',
initialValue: {},
'in': {
$cond:
[
{
$and:
[
{$or:[
{ $eq: [ "$$this.Type", '2' ] },
{$eq: [ "$$this.Type", '3' ] }
]},
{ $gt: [ "$$this.Date", "$$value.Date" ] },
]
}
,
"$$this.Amount",
0
]
}
}
}
}
}}]
the expected output would be which having the max date "2025-05-30T00:46:12.784Z"
{
_id :2018,
RecentValue : 340
}
Please let me know what mistake I did in the aggregate query.
You can get max date before $group stage,
$addFields to get document that having max date from, replaced $or with $in condition and corrected return value
$group by year and sum Amount
db.collection.aggregate([
{
$addFields: {
datum: {
$reduce: {
input: "$datum",
initialValue: {},
"in": {
$cond: [
{
$and: [
{ $in: ["$$this.Type", ["2", "3"]] },
{ $gt: ["$$this.Date", "$$value.Date"] }
]
},
"$$this",
"$$value"
]
}
}
}
}
},
{
$group: {
_id: "$year",
RecentValue: { $sum: "$datum.Amount" }
}
}
])
Playground
I am trying to generate a new collection with a field 'desc' having into account a condition in field in a documment array. To do so, I am using $cond statement
The origin collection example is the next one:
{
"_id" : ObjectId("5e8ef9a23e4f255bb41b9b40"),
"Brand" : {
"models" : [
{
"name" : "AA"
},
{
"name" : "BB"
}
]
}
}
{
"_id" : ObjectId("5e8ef9a83e4f255bb41b9b41"),
"Brand" : {
"models" : [
{
"name" : "AG"
},
{
"name" : "AA"
}
]
}
}
The query is the next:
db.runCommand({
aggregate: 'cars',
'pipeline': [
{
'$project': {
'desc': {
'$cond': {
if: {
$in: ['$Brand.models.name',['BB','TC','TS']]
},
then: 'Good',
else: 'Bad'
}
}
}
},
{
'$project': {
'desc': 1
}
},
{
$out: 'cars_stg'
}
],
'allowDiskUse': true,
})
The problem is that the $cond statement is always returning the "else" value. I also have tried $or statement with $eq or the $and with $ne, but is always returning "else".
What am I doing wrong, or how should I fix this?
Thanks
Since $Brand.models.name returns an array, we cannot use $in operator.
Instead, we can use $setIntersection which returns an array that contains the elements that appear in every input array
db.cars.aggregate([
{
"$project": {
"desc": {
"$cond": [
{
$gt: [
{
$size: {
$setIntersection: [
"$Brand.models.name",
[
"BB",
"TC",
"TS"
]
]
}
},
0
]
},
"Good",
"Bad"
]
}
}
},
{
"$project": {
"desc": 1
}
},
{
$out: 'cars_stg'
}
])
MongoPlayground | Alternative $reduce
New to Mongo, have found lots of examples of removing dupes from arrays of strings using the aggregation framework, but am wondering if possible to remove dupes from array of objects based on a field in the object. Eg
{
"_id" : ObjectId("5e82661d164941779c2380ca"),
"name" : "something",
"values" : [
{
"id" : 1,
"val" : "x"
},
{
"id" : 1,
"val" : "x"
},
{
"id" : 2,
"val" : "y"
},
{
"id" : 1,
"val" : "xxxxxx"
}
]
}
Here I'd like to remove dupes based on the id field. So would end up with
{
"_id" : ObjectId("5e82661d164941779c2380ca"),
"name" : "something",
"values" : [
{
"id" : 1,
"val" : "x"
},
{
"id" : 2,
"val" : "y"
}
]
}
Picking the first/any object with given id works. Just want to end up with one per id. Is this doable in aggregation framework? Or even outside aggregation framework, just looking for a clean way to do this. Need to do this type of thing across many documents in collection, which seems like a good use case for aggregation framework, but as I mentioned, newbie here...thanks.
Well, you may get desired result 2 ways.
Classic
Flatten - Remove duplicates (pick first occurrence) - Group by
db.collection.aggregate([
{
$unwind: "$values"
},
{
$group: {
_id: "$values.id",
values: {
$first: "$values"
},
id: {
$first: "$_id"
},
name: {
$first: "$name"
}
}
},
{
$group: {
_id: "$id",
name: {
$first: "$name"
},
values: {
$push: "$values"
}
}
}
])
MongoPlayground
Modern
We need to use $reduce operator.
Pseudocode:
values : {
var tmp = [];
for (var value in values) {
if !(value.id in tmp)
tmp.push(value);
}
return tmp;
}
db.collection.aggregate([
{
$addFields: {
values: {
$reduce: {
input: "$values",
initialValue: [],
in: {
$concatArrays: [
"$$value",
{
$cond: [
{
$in: [
"$$this.id",
"$$value.id"
]
},
[],
[
"$$this"
]
]
}
]
}
}
}
}
}
])
MongoPlayground
You can use $reduce, Try below query :
db.collection.aggregate([
{
$addFields: {
values: {
$reduce: {
input: "$values",
initialValue: [],
in: {
$cond: [
{ $in: ["$$this.id", "$$value.id"] }, /** Check if 'id' exists in holding array if yes push same array or concat holding array with & array of new object */
"$$value",
{ $concatArrays: ["$$value", ["$$this"]] }
]
}
}
}
}
}
]);
Test : MongoDB-Playground
{
_id: ObjectId("5dbdacc28cffef0b94580dbd"),
"comments" : [
{
"_id" : ObjectId("5dbdacc78cffef0b94580dbf"),
"replies" : [
{
"_id" : ObjectId("5dbdacd78cffef0b94580dc0")
},
]
},
]
}
How to count the number of element in comments and sum with number of relies
My approach is do 2 query like this:
1. total elements of replies
db.posts.aggregate([
{$match: {_id:ObjectId("5dbdacc28cffef0b94580dbd")}},
{ $unwind: "$comments",},
{$project:{total:{$size:"$comments.replies"} , _id: 0} }
])
2. count total elements of comments
db.posts.aggregate([
{$match: {_id:ObjectId("5dbdacc28cffef0b94580dbd")}},
{$project:{total:{$size:"$comments.replies"} , _id: 0} }
])
Then sum up both, do we have any better solution to write the query like return the sum of of total element comments + replies
You can use $reduce and $concatArrays to "merge" an inner "array of arrays" into a single list and measure the $size of that. Then simply $add the two results together:
db.posts.aggregate([
{ "$match": { _id:ObjectId("5dbdacc28cffef0b94580dbd") } },
{ "$addFields": {
"totalBoth": {
"$add": [
{ "$size": "$comments" },
{ "$size": {
"$reduce": {
"input": "$comments.replies",
"initialValue": [],
"in": {
"$concatArrays": [ "$$value", "$$this" ]
}
}
}}
]
}
}}
])
Noting that an "array of arrays" is the effect of an expression like $comments.replies, so hence the operation to make these into a single array where you can measure all elements.
Try using the $unwind to flatten the list you get from the $project before using $count.
This is another way of getting the result.
Input documents:
{ "_id" : 1, "array1" : [ { "array2" : [ { id: "This is a test!"}, { id: "test1" } ] }, { "array2" : [ { id: "This is 2222!"}, { id: "test 222" }, { id: "222222" } ] } ] }
{ "_id" : 2, "array1" : [ { "array2" : [ { id: "aaaa" }, { id: "bbbb" } ] } ] }
The query:
db.arrsizes2.aggregate( [
{ $facet: {
array1Sizes: [
{ $project: { array1Size: { $size: "$array1" } } }
],
array2Sizes: [
{ $unwind: "$array1" },
{ $project: { array2Size: { $size: "$array1.array2" } } },
],
} },
{ $project: { result: { $concatArrays: [ "$array1Sizes", "$array2Sizes" ] } } },
{ $unwind: "$result" },
{ $group: { _id: "$result._id", total1: { $sum: "$result.array1Size" }, total2: { $sum: "$result.array2Size" } } },
{ $addFields: { total: { $add: [ "$total1", "$total2" ] } } },
] )
The output:
{ "_id" : 2, "total1" : 1, "total2" : 2, "total" : 3 }
{ "_id" : 1, "total1" : 2, "total2" : 5, "total" : 7 }
I have used aggregation to find below output.
Next step is to divide the values of elements present in each array.
{
"_id" : {
“type”:”xxx”,
"year" : 2019
},
"allvalues" : [
{
"label" : “used”,
"value" : 50
},
{
"label" : “total”,
"value" : 58
}
]
}
{
"_id" : {
“type”:”yyy”,
"year" : 2019
},
"allvalues" : [
{
"label" : “used”,
"value" : 63.214285714285715
},
{
"label" : “total”,
"value" : 59.535714285714285
}
]
}
How to write the query to divide used/total in each doc.
For first doc it is 50/58 and second doc it is 63.21/59.53.
The structure of json remains constant.
Output should look like below:
{
“type”:”xxx”,
"year" : 2019,
“result” : 0.8
}
{
“type”:”yyy”,
"year" : 2019,
“result” : 1.06
}
Add this in the aggregate pipeline after you get above input first you need to use $filter and $arrayElemAt to get used and total's value after that as divide doesn't give fixed decimal place, I've used $trunc to make value to 2 decimal fixed place
{
$project: {
_id: 1,
used: {
$arrayElemAt: [
{
$filter: {
input: "$allvalues",
as: "item",
cond: {
$eq: [
"$$item.label",
"used"
]
}
}
},
0
]
},
total: {
$arrayElemAt: [
{
$filter: {
input: "$allvalues",
as: "item",
cond: {
$eq: [
"$$item.label",
"total"
]
}
}
},
0
]
},
}
},
{
$project: {
_id: 1,
result: {
$divide: [
{
$trunc: {
$multiply: [
{
$divide: [
"$used.value",
"$total.value"
]
},
100
]
}
},
100
]
}
}
}