Grouping Mongo DB document with three nested arrays - arrays

Question

I have a Mongo document with three nested arrays. Inside the document linearTvSessions, I have an array of linearTvChannels which has an array of sessions which has an array of tunerDetails.
{
"_id": "GATES:1123:E8186354149C:2022-03-04",
"date": {
"$date": {
"$numberLong": "1646352000000"
}
},
"lastReportedTime": {
"$date": {
"$numberLong": "1646436034000"
}
},
"macAddress": "E8186354149C",
"propCode": "GATES",
"roomNumber": "1123",
"linearTvChannels": [
{
"channelId": 3,
"channelName": "WMC",
"sessions": [
{
"created": {
"$date": {
"$numberLong": "1646435214000"
}
},
"duration": 170,
"isOccupied": 0,
"startTime": {
"$date": {
"$numberLong": "1646435044000"
}
},
"stopTime": {
"$date": {
"$numberLong": "1646435214000"
}
},
"tunerDetails": [
{
"created": {
"$date": {
"$numberLong": "1646435044000"
}
},
"errorLevel": 0,
"signalLevel": 44,
"signalLocked": 1,
"signalQuality": 91
},
{
"created": {
"$date": {
"$numberLong": "1646435104000"
}
},
"errorLevel": 0,
"signalLevel": 4487,
"signalLocked": 0,
"signalQuality": 1111
},
{
"created": {
"$date": {
"$numberLong": "1646435164000"
}
},
"errorLevel": 0,
"signalLevel": 44,
"signalLocked": 0,
"signalQuality": 63
}
]
}
]
}
]
}
Current output:
{
_id: 'GATES:1123:E8186354149C:2022-03-04',
lastReportedTime: 2022 - 03 - 04 T23: 20: 34.000 Z,
propCode: 'GATES',
roomNumber: '1123',
macAddress: 'E8186354149C',
date: 2022 - 03 - 04 T00: 00: 00.000 Z,
linearTvChannels: [{
channelName: 'WMC',
channelId: 3,
sessions: [{
created: 2022 - 03 - 04 T23: 06: 54.000 Z,
duration: 170,
isOccupied: 0,
startTime: 2022 - 03 - 04 T23: 04: 04.000 Z,
stopTime: 2022 - 03 - 04 T23: 06: 54.000 Z,
tunerDetails: {
created: 2022 - 03 - 04 T23: 05: 04.000 Z,
errorLevel: 0,
signalLevel: 4487,
signalLocked: 0,
signalQuality: 1111
}
},
{
created: 2022 - 03 - 04 T23: 06: 54.000 Z,
duration: 170,
isOccupied: 0,
startTime: 2022 - 03 - 04 T23: 04: 04.000 Z,
stopTime: 2022 - 03 - 04 T23: 06: 54.000 Z,
tunerDetails: {
created: 2022 - 03 - 04 T23: 06: 04.000 Z,
errorLevel: 0,
signalLevel: 44,
signalLocked: 0,
signalQuality: 63
}
}]
}]
}
Desired output:
{
_id: 'GATES:1123:E8186354149C:2022-03-04',
lastReportedTime: 2022 - 03 - 04 T23: 20: 34.000 Z,
propCode: 'GATES',
roomNumber: '1123',
macAddress: 'E8186354149C',
date: 2022 - 03 - 04 T00: 00: 00.000 Z,
linearTvChannels: [{
channelName: 'WMC',
channelId: 3,
sessions: [{
created: 2022 - 03 - 04 T23: 06: 54.000 Z,
duration: 170,
isOccupied: 0,
startTime: 2022 - 03 - 04 T23: 04: 04.000 Z,
stopTime: 2022 - 03 - 04 T23: 06: 54.000 Z,
tunerDetails: [{
created: 2022 - 03 - 04 T23: 05: 04.000 Z,
errorLevel: 0,
signalLevel: 4487,
signalLocked: 0,
signalQuality: 1111
},
{
created: 2022 - 03 - 04 T23: 06: 04.000 Z,
errorLevel: 0,
signalLevel: 44,
signalLocked: 0,
signalQuality: 63
}]
}]
}]
}
My Current query:
db.linearTvSessions.aggregate(
[{$unwind:"$linearTvChannels"}, {$unwind:"$linearTvChannels.sessions"}, {$unwind:"$linearTvChannels.sessions.tunerDetails"},
{$match:{"linearTvChannels.sessions.tunerDetails.signalLocked":0}},
{ "$group": {
"_id": {
"_id": "$_id",
"channelName": "$linearTvChannels.channelName",
"channelId": "$linearTvChannels.channelId"
},
"lastReportedTime": { "$first": "$lastReportedTime" },
"propCode": { "$first": "$propCode" },
"roomNumber": { "$first": "$roomNumber" },
"macAddress": { "$first": "$macAddress" },
"date": { "$first": "$date" },
"sessions": { "$push": "$linearTvChannels.sessions" }
}},
{ "$group": {
"_id": "$_id._id",
"lastReportedTime": { "$first": "$lastReportedTime" },
"propCode": { "$first": "$propCode" },
"roomNumber": { "$first": "$roomNumber" },
"macAddress": { "$first": "$macAddress" },
"date": { "$first": "$date" },
"linearTvChannels": { "$push": {
"channelName": "$_id.channelName",
"channelId": "$_id.channelId",
"sessions": "$sessions"
}}
}}
]
);
I unwind the three arrays in the query above and inside the third array tunerDetails, I'm matching on the signalLocked field. I'm having trouble grouping the tunerDetails in an array by sessions. In my output above, each tunerDetails is placed in a redundant session. This is expected behavior but I'm trying to place the tunerDetails in an array as shown in my desired output.
I create a third group operation with the id of sessions details similar to this but I'm loosing track of linearTvChannels details when I do so.
{ "$group": {
"_id": {
"created": "$linearTvChannels.sessions.created",
"duration": "$linearTvChannels.sessions.duration",
"isOccupied": "$linearTvChannels.sessions.isOccupied",
"startTime": "$linearTvChannels.sessions.startTime",
"stopTime": "$linearTvChannels.sessions.stopTime"
},
"tunerDetails": { "$push": "$linearTvChannels.sessions.tunerDetails" }
}}
I feel like I'm not grouping by the ids properly?

Answer 1

If the innermost array is the only thing to be modified, you could accomplish this with $map and $filter:
$map over linearTvChannels, replace with the result of the map
$map over sessions, replace with the result of the map
$filter tunerDetails, keeping only those with signalLocked 0
This could be done in a single $addFields stage like so:
{$addFields: {
linearTvChannels: {$map: {
input: "$linearTvChannels",
as: "chan",
in: {$mergeObjects: [
"$$chan",
{sessions: {
$map: {
input: "$$chan.sessions",
as: "session",
in: {"$mergeObjects": [
"$$session",
{tunerDetails: {
$filter: {
input: "$$session.tunerDetails",
cond: {$eq: ["$$this.signalLocked",0]}
}
}}
]}
}
}}
]}
}
}
}}
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