db={"products":[{"_id":ObjectId("6044351794bee8b6e0fce48f"),"sku":"P003474","name":"Kitchen Wash"},{"_id":ObjectId("6085584c42ad3c58c5dbc6b7"),"sku":"TS0012","name":"T-shirt"},{"_id":ObjectId("608d20a90e629fcc0d3a93e1"),"sku":"Apple1101","name":"Green Apple"}],"wishlists":[{"_id":ObjectId("608d8af12b7556c445f5cd87"),"product":ObjectId("6044351794bee8b6e0fce48f"),"user":ObjectId("601fb31a60e0a024143e6ea3"),"isLiked":false},{"_id":ObjectId("608d8bad2b7556c445f5cd88"),"product":ObjectId("6085584c42ad3c58c5dbc6b7"),"user":ObjectId("601fb31a60e0a024143e6ea3"),"isLiked":true}]}

db.products.aggregate([{$lookup:{from:"wishlists",localField:"_id",foreignField:"product",as:"product"}},{$unwind:{path:"$product",preserveNullAndEmptyArrays:true}}])