Aggregate multiple arrays by field value [duplicate] - mongodb

Question

This question already has an answer here:
mongodb aggregate multiple arrays
(1 answer)
Closed 4 years ago.
With a document as shown below, I am trying to aggregate the data so my final output is the sum of each users received and sent values.
Document
{
"_id" : 1,
"received" : [
{ "name" : "david", "value" : 15 },
{ "name" : "sarah", "value" : 10 },
{ "name" : "sarah", "value" : 15 }
],
"sent" : [
{ "name" : "david", "value" : 10 },
{ "name" : "sarah", "value" : 20 },
{ "name" : "david", "value" : 15 }
]
}
Desired Result (or similar)
{
"name": "david",
"received": 15,
"sent": 25
},
{
"name": "sarah",
"received": 25,
"sent": 20
}
I have tried to unwind received and sent, but I am ending up with a lot of duplicates and honestly I have no idea if this sort of output can even be created without bringing the dataset into my client first.
Further searching of StackOverflow has lead me to mongodb aggregate multiple arrays that provides a suitable answer. I have flagged this as a duplicate.
My final solution, created by following the above post, is as follows;
[
{
'$addFields': {
'received.type': 'received',
'sent.type': 'sent'
}
}, {
'$project': {
'movements': {
'$concatArrays': [
'$received', '$sent'
]
}
}
}, {
'$unwind': {
'path': '$movements'
}
}, {
'$project': {
'name': '$movements.name',
'type': '$movements.type',
'value': '$movements.value'
}
}, {
'$group': {
'_id': '$name',
'sent': {
'$sum': {
'$cond': {
'if': {
'$eq': [
'$type', 'sent'
]
},
'then': '$value',
'else': 0
}
}
},
'received': {
'$sum': {
'$cond': {
'if': {
'$eq': [
'$type', 'received'
]
},
'then': '$value',
'else': 0
}
}
}
}
}
]

Answer 1

add $match stage on the top to filter the documents
$facet to compute two different result by sent and received on same document
$group to merge the by sent and received fields of previous stage
$unwind & $unwind to unwind the merged array of array
$replaceRoot to replace root with byBoth
$group to merge the results back
$project to filter and project required fields only
aggregation pipeline
db.ttt.aggregate([
{$facet : {
"byReceived" :[
{$unwind : "$received"},
{$group: {_id : "$received.name", received : {$sum : "$received.value"}}}
],
"bySent" :[
{$unwind : "$sent"},
{$group: {_id : "$sent.name", sent : {$sum : "$sent.value"}}}
]
}},
{$group: {_id:null, byBoth : {$push :{$concatArrays : ["$bySent", "$byReceived"]}}}},
{$unwind : "$byBoth"},
{$unwind : "$byBoth"},
{$replaceRoot: { newRoot: "$byBoth" }},
{$group : {_id : "$_id", sent : {$sum : "$sent"}, received : {$sum : "$received"}}},
{$project : {_id:0, name:"$_id", sent:"$sent", received:"$received"}}
])
result
{ "name" : "david", "sent" : 25, "received" : 15 }
{ "name" : "sarah", "sent" : 20, "received" : 25 }