Add new id (from migration)

Working with Data
,
1

Hello! I have migrated from an SQL server over to Mongodb. Could somebody help me how to do this? I simply want to update the deals collection by adding a new store field on all of the the deals to reference the store id. But I only got the old id from the previous system. (So it’s many stores and many many deals)

stores collection:
{
    _id: ObjectId("63b99eb127647f05bffaaa13"),
    oldId: 425,
    name": "Ikea"
}

deals collection:
{
    _id: ObjectId("63b9de7ab898047ba0e5c876"),
    title: "Red chairs",
    oldStoreId: 425
}

expected result on deals collection:
{
    _id: ObjectId("63b9de7ab898047ba0e5c876"),
    title: "Red chairs",
    oldStoreId: 425,
    store: ObjectId("63b99eb127647f05bffaaa13")
}
2

Have a look at @turivishal’s answer in this thread