Mongodb: splite string in aggregation pipeline - mongodb

Question

this is my document that had stored into collection:
{
"_id" : UUID("61a2053c-1a79-4649-8793-df6c4dc1973"),
"NotificationId" : UUID("ad068e4e-10e2-528c-a74a-df6c4dd9211"),
"DistributionId" : UUID("f5445ea1-e6cb-4acd-9881-c4122df6c4d"),
"CreationDateTime" : ISODate("2016-07-13T04:20:38.697Z"),
"ExpirationDateTime" : ISODate("2099-01-01T00:00:00.000Z"),
"DeliveryType" : 1,
"DeliveryParams" : [],
"Address" : "Topics/Messages/Global",
"Payload" : "{\"Id\":\"ad067896-10e2-528c-er87-df6c4d123654\",\"CreationDateTime\":\"\\/Date(1468324824751)\\/\",\"DeviceId\":\"456987456985\",\"UserId\":\"64545678-1234-4834-4321-123456789012\",\"UserFullName\":\"test-user\",\"SystemId\":\"com.messaging\",\"SystemTitle\":\"message\",\"EventId\":\"messaging.message\",\"EventTitle\":\"ارسال پیام\",\"EventData\":[],\"BusinessCode\":\"1-2-4-4-5-6-9\",\"ProcessId\":\"55333333-4433-3333-7733-113333333399\",\"WorkItemId\":423458,\"WKT\":\"\"}",
"SendAttempts" : null,
"Sent" : ISODate("2016-11-10T10:01:22.140Z"),
"Delivered" : ISODate("1970-01-01T00:00:00.000Z")
}
My question is, How could I split \"BusinessCode\":\"1-2-4-4-5-6-9\" inside
Payload field. I just need BusinessCode:1-2-4-4-5-6-9 for store into the other field.
I used this script:
db.Messages.find().forEach(function(item)
{
id = item._id;
payload = item.Payload;
matched = payload.match(/\"BusinessCode\":\"(([1-2]?[0-9])-([0-9]*)-([0-9]*)-([0-9]*)-([0-9]*)-([0-9]*)-([0-9]*))\"/);
....
db.Messages.updateOne(
....
This payload.match return
BusinessCode":"1-2-4-4-5-6-9",1-2-4-4-5-6-9,1,2,4,4,5,6,9
this script for collection with a many document is not appropriate and has a low speed. I want to use aggregation pipeline.
How could I get exactly same response like payload.match, into aggregation pipeline ?

Answer 1

we don't have regexp substring in mongo as of 3.6.2
we can use substr methods to substring the business id, since the payload contains unicode characters, we need to use CodePoint (CP) to get the expected results
db.col.aggregate(
[
{$addFields : {
start : {$indexOfCP : ["$Payload", "BusinessCode"]},
end : { $indexOfCP : ["$Payload", "ProcessId"]}
}
},
{$project : {BusinessCode : {$substrCP : ["$Payload", {$sum : ["$start",15]}, {$subtract : [{$subtract : ["$end", "$start"]}, 18]}]}}}
]
)
result
{ "_id" : "61a2053c-1a79-4649-8793-df6c4dc1973", "BusinessCode" : "1-2-4-4-5-6-9" }