db={products:[{"isActive":true,"_id":"643bbdee68b521035e20c976","name":"lu","price":123,"userId":"643abd0dcce4df3b1a0c8fa7"},{"_id":"643bbdd668b521035e20c972","name":"mu","price":123,"userId":"643abd0dcce4df3b1a0c8fa7","isActive":true,"__v":0},{"isActive":true,"_id":"643bbdbc68b521035e20c971","name":"nu","price":123,"userId":"643abd0dcce4df3b1a0c8fa7"},{"_id":"643c2dc126211992b4ee8fd5","name":"pu","price":123,"userId":"643abd0dcce4df3b1a0c8fa7","isActive":true}],subproducts:[{"_id":"643d7ed82cd5b5fcd7e81e02","name":"kkkk","phoneNum":9543922499,"productID":"643bbdee68b521035e20c976","user":"643abd0dcce4df3b1a0c8fa7","address":{"address1":"243, bastin nagarsss","zipCode":6250185}}]}

db.subproducts.aggregate([{"$lookup":{"from":"products","localField":"productID","foreignField":"_id","as":"product_details"}}])