need to convert the data in another format - mongodb

Question

We have Data:
[
{
"_id": ObjectId("5f87e152219aaf1f9404ef3f"),
"parameterId": "5f914ca2679bae721d38410b",
"average": 574998.153846154,
"count": 26.0,
"date": ISODate("2020-09-08T18:30:00.000Z"),
"_class": "org.nec.iotplatform.entities.RawData"
},
{
"_id": ObjectId("5f87e1e2219aaf1f9404eff5"),
"parameterId": "5f914ca2679bae721d38410b",
"average": 494217.606225681,
"count": 1285.0,
"date": ISODate("2020-09-09T18:30:00.000Z"),
"_class": "org.nec.iotplatform.entities.RawData"
}
]
I have query which I am executing on above data and then getting the result as below the query
db.collection.aggregate([
{
"$project": {
"year": {
"$year": "$date"
},
"month": {
"$month": "$date"
},
"dayOfMonth": {
"$dayOfMonth": "$date"
},
"average": "$average",
"count": "$count",
"Symbol": 1
}
},
{
"$group": {
"_id": {
year: "$year",
month: "$month",
dayOfMonth: "$dayOfMonth"
},
"data": {
"$push": "$$ROOT"
}
}
},
{
"$project": {
"average": {
"$divide": [
{
"$reduce": {
"input": "$data",
"initialValue": 0,
"in": {
"$add": [
"$$value",
{
"$multiply": [
"$$this.count",
"$$this.average"
]
}
]
}
}
},
{
$reduce: {
input: "$data",
initialValue: 0,
in: {
"$add": [
"$$value",
"$$this.count"
]
}
}
}
]
}
}
}
])
I am getting output :
[{
"_id" : {
"year" : 2020,
"month" : 9,
"dayOfMonth" : 8
},
"average" : 574998.153846154
},
{
"_id" : {
"year" : 2020,
"month" : 9,
"dayOfMonth" : 9
},
"average" : 494217.606225681
}]
But I need to format the result data like this. by adding the date like this:
{
2020-09-08T18:30:00.000Z : 574998.153846154,
2020-09-09T18:30:00.000Z : 494217.606225681
}
Thanks in advance.

Answer 1

You can use $dateFromString to create the date you want.
Also, you need $concat and $toString to parse the numbers to string and concat into a single string.
After that, using $group you can get the all values you need in the same array. And how you want set the date as KEY, is neccesary create fields k and v and parse again to string.
With the values together, using $arrayToObject you can cerate the schema you want date: average and use $replaceRoot to get only the values at top level.
To do this you need to add this query at the end of your aggregation.
{
"$set": {
"date": { "$dateFromString": { "dateString": {
"$concat": [
{ "$toString": "$_id.dayOfMonth" }, "-",
{ "$toString": "$_id.month" }, "-",
{ "$toString": "$_id.year" }
] },
"format": "%d-%m-%Y", "timezone": "Europe/Madrid"
} } }
},
{
"$group": {
"_id": null,
"date": { "$push": { "k": { "$toString": "$date" }, "v": "$average" } }
}
},
{
"$replaceRoot": { "newRoot": { "$arrayToObject": "$date" } }
}
This query add a new field called date like this:
"date": ISODate("2020-09-08T04:00:00Z")
I've used Europe/Madrid as timezone but you can choose you want to get your desired date.
Example here.
The output is:
{
"2020-09-07T22:00:00.000Z": 574998.153846154,
"2020-09-08T22:00:00.000Z": 494217.606225681
}
Using America/New_York as timezone:
{
"2020-09-08T04:00:00.000Z": 574998.153846154,
"2020-09-09T04:00:00.000Z": 494217.606225681
}