Need help filtering documents with criteria inside array - mongoDB - mongodb

Question

Need help with query to filter the records in mongoDB. I am using compass to run the que
We have thousands of records/documents where each record/document contains the following array. For few documents, the events in lifeCycleinfo are out of order i.e. payment.completed event comes before 1payment.completed1 event.
I need to filter those records where completed event comes before created event
{
"lifeCycleInfo": [
{
"eventId": "9b8b6adfae",
"eventSubType": "SendTransfer_Receipt",
"eventType": "SendTransfer",
"odsTimestamp": {
"$date": "2023-02-06T14:33:42.308Z"
},
"payload": "{}",
"timestamp": {
"$date": "2023-02-06T14:33:42.271Z"
}
},
{
"eventId": "06e8d144-531b02",
"eventSubType": "payment.created",
"eventType": "Notification",
"odsTimestamp": {
"$date": "2023-02-06T14:33:45.488Z"
},
"payload": "{}",
"timestamp": {
"$date": "2023-02-06T14:33:45.479Z"
}
},
{
"eventId": "9da54454d6",
"eventSubType": "payment.completed",
"eventType": "Notification",
"odsTimestamp": {
"$date": "2023-02-06T14:33:46.698Z"
},
"payload": "{}",
"timestamp": {
"$date": "2023-02-06T14:33:46.689Z"
}
}
]
}
I tried to find it based on array index but not working.
{"lifeCycleInfo[1].eventtype":"payment.completed"}

Answer 1

You can use $reduce with $switch to iterate through the lifeCycleInfo array and keep track of the status with an object {inOrder: <bool>, seenCreated: <bool>}. We can conditionally set the 2 bools and use the final result to get the matched documents.
db.collection.aggregate([
{
$set: {
inOrderResult: {
"$reduce": {
"input": "$lifeCycleInfo",
"initialValue": {
inOrder: false,
seenCreated: false
},
"in": {
"$switch": {
"branches": [
{
"case": {
$eq: [
"$$this.eventSubType",
"payment.created"
]
},
"then": {
inOrder: "$$value.inOrder",
seenCreated: true
}
},
{
"case": {
$and: [
{
$eq: [
"$$this.eventSubType",
"payment.completed"
]
},
{
$eq: [
"$$value.seenCreated",
true
]
}
]
},
"then": {
inOrder: true,
seenCreated: true
}
}
],
default: "$$value"
}
}
}
}
}
},
{
$match: {
"inOrderResult.inOrder": true
}
}
])
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