Queries in MongoDB

[ntthai3011]

I have a query like that:

{
    "collection": "transactions",
    "aggregate": [
        {
            "$match": {
                "trx_loyalMem_createdDate": {
                    "$gte": "ISODate(\"{{ FromDate }}\")",
                    "$lte": "ISODate(\"{{ ToDate }}\")"
                },
                "trx_loyalMem_number": {
                    "$exists": true
                }
            }
        },
        {
            "$lookup": {
                "from": "report_data",
                "localField": "trx_loyalMem_number",
                "foreignField": "pid",
                "as": "report_data"
            }
        },
        {
            "$unwind": "$report_data"
        }
    ]
}

And when I run it, if there are 2 rows, then the column number will be duplicated 2 times, if there are 3 rows, then the column number will also be duplicated 3 times. This means that no matter how many rows there are, the number of columns will be duplicated.
How do I fix it?