Match and add new field to each array elements in Mongodb aggregation - mongodb

Question

I have two collections below and I'm creating a view table by using the aggregation and merge.
account table:
{
"_id": {
"$oid": "5f61b573db16185cebfeaaf9"
},
"status": "ACTIVE",
"personalInfo": {
"entityName": "John Doe",
...
},
"createdDateTime": {
"$date": "2020-09-16T06:49:23.103Z"
},
"modifiedDateTime": {
"$date": "2020-09-16T06:49:23.103Z"
}
}
account_transactions:
{
"_id": {
"$oid": "5f61b5b3db16185cebfeab0c"
},
"accountId": "5f61b573db16185cebfeaaf9",
"transactionType": "Payment",
"transactionStatus": "NEW",
"createdDate": {
"$date": "2020-09-16T06:50:27.305Z"
},
"createdBy": "sujal.shakya#joinsage.com",
"lastModifiedDate": {
"$date": "2020-09-16T10:23:06.617Z"
}
}
{
"_id": {
"$oid": "5f61b5b3db16185cebfeab0f"
},
"accountId": "5f61b573db16185cebfeaaf9",
"transactionType": "Credit",
"createdDate": {
"$date": "2020-09-16T06:50:27.305Z"
},
"createdBy": "sujal.shakya#joinsage.com",
"lastModifiedDate": {
"$date": "2020-09-16T10:23:06.617Z"
}
}
Below mongodb query creates a view table with each account having multiple transactions if exist and if no transactions exists then adds dummy transaction to with some dummy fields.
db.account.aggregate(
[
{
$match: {
'status': 'ACTIVE'
}
},
{$addFields: {"accountId": {"$toString": "$_id"}}},
{
$lookup: {
from: "account_transactions",
localField: "accountId",
foreignField: "accountId",
as: "transactions"
}
},
{
"$project": {
"accountType": 1,
"transactions": {
"$cond": [
{ "$eq": [ "$transactions", [] ] },
{$concatArrays: [[{"lastModifiedDate": {$arrayElemAt: ["$account.modifiedDateTime",0]}, "transactionType" : "BLANK"}]] },//adds dummy fields
{"$filter": {
"input": "$transactions",
"as": "transactions",
"cond": {
"$or": [
{
"$eq": [
"$$transactions.transactionType",
"Payment"
]
},
{
"$eq": [
"$$transactions.transactionType",
"Sale"
]
},
{
"$eq": [
"$$transactions.transactionType",
"Debit"
]
}
]
}
}
}
},
"createdBy": 1
}
},
{$merge: {into: "account_view_table", on: "_id", whenMatched: "replace", whenNotMatched: "insert"}}
])
What I need to do now is to add a new field in the view table is created above for each transactions by matching transaction type. For example: if an account has multiple transactions each with different transaction type, then check the transactionType of each transactions and add new fields "transactionTypeOrder" on each like:
I've been trying different things but nothing is working
{$addFields: {"transactions.transactionTypeOrder" :
{
$cond: [{$in:["$transactions.transactionType",["Payment"]]},"1",
{$cond: [ {$in:["$transactions.transactionType",["Sale"]]},"2",
{$cond: [{$in:["$transactions.transactionType",["Debit"]]},"3", "4" ]}
]}
]
}
}},
So if transactionType == "Payment" add transactionTypeOrder: 1, if transactionType == "Sales" add transactionTypeOrder: 2 etc. The output I'm looking for is something like below:
Case for 2nd Case checking another field also :
In the same transactions, I also have to do another check with different field to check if "transactionStatus" field exists and if not exists add "transactionStatusOrderAsc" field as "####" and "transactionStatusOrderDsc" as "~~~" and if exist same value as "transactionStatus" So the output will be as below:
So basically, I have to check transactionType and add new Filed and also at the same time check transactionStatus and two need fields.
//result view table
{
"_id": {
"$oid": "5f61b573db16185cebfeaafd"
},
//...other fields.
"transactions": [{
"transactionType": "Payment",
"transactionTypeOrder": 1,
"transactionStatus": "New",
"transactionStatusOrderAsc": "New",
"transactionStatusOrderDsc": "New"
},
{
"transactionType": "Sales",
"transactionTypeOrder": 2,
"transactionStatusOrderAsc": "####", //since transactionStatus field doesn't exist here
"transactionStatusOrderDsc": "~~~~"
},
{
"transactionType": "Debit",
"transactionTypeOrder": 3,
"transactionStatus": "Old",
"transactionStatusOrderAsc": "Old",
"transactionStatusOrderDsc": "Old"
}
]
}

Answer 1

You can use $map to apply to each element of your array, and $switch to check value and add your field.
db.account.aggregate([
{
$match: {
"status": "ACTIVE"
}
},
{
$addFields: {
"accountId": {
"$toString": "$_id"
}
}
},
{
$lookup: {
from: "account_transactions",
localField: "accountId",
foreignField: "accountId",
as: "transactions"
}
},
{
"$project": {
"accountType": 1,
"createdBy": 1,
transactions: /**adds dummy fields*/
{
"$map": {
"input": "$transactions",
"as": "transactions",
"in": {
$switch: {
branches: [
{
case: {
$eq: [
"$$transactions.transactionType",
"Payment"
]
},
then: {
transactionType: "$$transactions.transactionType",
transactionTypeOrder: 1
}
},
{
case: {
$eq: [
"$$transactions.transactionType",
"Sales"
]
},
then: {
transactionType: "$$transactions.transactionType",
transactionTypeOrder: 2
}
},
{
case: {
$eq: [
"$$transactions.transactionType",
"Debit"
]
},
then: {
transactionType: "$$transactions.transactionType",
transactionTypeOrder: 3
}
},
],
default: {
transactionType: "$$transactions.transactionType",
transactionTypeOrder: -1
}
}
}
}
}
}
},
])
If you need other field of each transaction, you have to add them in each case condition.
You can test it here
EDIT FROM FIRST COMMENT
If you have to include all your transactions fields, you can use $mergeObjects instead of manually creating your object.
db.account.aggregate([
{
$match: {
"status": "ACTIVE"
}
},
{
$addFields: {
"accountId": {
"$toString": "$_id"
}
}
},
{
$lookup: {
from: "account_transactions",
localField: "accountId",
foreignField: "accountId",
as: "transactions"
}
},
{
"$project": {
"accountType": 1,
"createdBy": 1,
transactions: /**adds dummy fields*/
{
"$map": {
"input": "$transactions",
"as": "transactions",
"in": {
$switch: {
branches: [
{
case: {
$eq: [
"$$transactions.transactionType",
"Payment"
]
},
then: {
$mergeObjects: [
"$$transactions",
{
transactionTypeOrder: 1
}
]
}
},
{
case: {
$eq: [
"$$transactions.transactionType",
"Sales"
]
},
then: {
$mergeObjects: [
"$$transactions",
{
transactionTypeOrder: 2
}
]
}
},
{
case: {
$eq: [
"$$transactions.transactionType",
"Debit"
]
},
then: {
$mergeObjects: [
"$$transactions",
{
transactionTypeOrder: 3
}
]
}
},
],
default: {
$mergeObjects: [
"$$transactions",
{
transactionTypeOrder: -1
}
]
}
}
}
}
}
}
},
])
Test it here