Data transformation using triggers with aggregation

[Vinay_Gangaraj]

Hi,

I have a document in the below structure in collection A and I am using Database triggers with aggregation to transform the data and push the transformed data to collection B.

Document in Collection A:

{
    "_id" : "BRS1736451",
    "BookingNum" : "BRS1736451",
    "AccountId" : "0010Q00000xMDB6QAO",
    "BookingLines" : [ 
        {
            "BookingLines" : {
                "BookingLine_id" : 11289009,
                "ParentLineId" : null,
                "MarketKey" : "Brazil"
            }
        }, 
        {
            "BookingLines" : {
                "BookingLine_id" : 11289014,
                "ParentLineId" : null,
                "MarketKey" : "Brazil"
            }
        }
	]
}

In the collection B, I need below changes

1. Create own mongo db bson id
2. all fields should be in camel case
3. Booking Lines in collection A is Array of nested BookingLines Objects. But, in collection B I just need just array of objects as mentioned above.

Transformed Data needed in Collection B will look like below:

{
    "_id" : ObjectId("5f9ff6744bcc4ae435f10760"),
    "bookingNumber" : "BRS1736451",
    "accountId" : "0010Q00000xMDB6QAO",
    "bookingLines" : [ 
        {
			"bookingLineId" : 11289009,
			"lineId" : null,
			"marketKey" : "Brazil"
        }, 
        {
			"bookingLineId" : 11289014,
			"lineId" : null,
			"marketKey" : "Brazil"

        }
	]
}

I am trying to use the below code which is working fine for first 2 requirements but for the 3rd requirement i.e. booking Lines are not getting transformed according to my expectation.

Code snippet:

exports = function(fullDocument){

console.log('BookingNumber: ' + fullDocument.BookingNum);

const pipeline = [
  {
     $project: {
      _id: 0,
      bookingNumber: fullDocument.BookingNum,
      accountId: fullDocument.AccountId,
      bookingLines: fullDocument.BookingLines,
      }
  },
  {
     $addFields: {
        bookingLines: {
        $map: {
          input: "$bookingLines",
          as: "bookingLine",
          in: {
			      bookingLineId: "$$bookingLine.BookingLine_id",
				parentBookingLineId: "$$bookingLine.ParentBookingLine_id",
				  marketKey: "$$bookingLine.MarketKey"
}}}
}},
  {
    $merge: {
      into: 'B', 
      on: 'bookingNumber',
      whenMatched: 'replace', 
      whenNotMatched: 'insert'
    }
  }
];

const collectionA = context.services.get("Cluster0").db("XXXX").collection("A");

return collectionA.aggregate(pipeline).toArray().then(() => {
    console.log(`Successfully moved ${fullDocument.bookingNumber} data to B collection.`);
  })
  .catch(err => console.error(`Failed to move ${fullDocument.bookingNumber} data to B collection: ${err}`));
};

Please help me on this.

Thanks,
Vinay

[Prasad_Saya]

Hello @Vinay_Gangaraj.

I am trying to use the below code which is working fine for first 2 requirements but for the 3rd requirement i.e. booking Lines are not getting transformed according to my expectation.

Try this $addFields stage. Replace with this one in the aggregation to transform the 3rd requirement about the Booking Lines:

{
    $addFields: {
        bookingLines: {
            $map: {
                 input: "$bookingLines",
                 in: {
                     bookingLineId: "$$this.BookingLines.BookingLine_id",
                     lineId: "$$this.BookingLines.ParentLineId",
                     marketKey: "$$this.BookingLines.MarketKey"
                 }
            }
        }
    }
}