Is it possible to rename _id field after mongo's group aggregation?

Question

I have a query like this (simplified):

db.report.aggregate([{
        $match: {
            main_id: ObjectId(\"58f0f67f50c6af16709fd2c7\")
        }
    },          


        

Answer 1

From mongo v3.4 you could use $addFields in conjunction with $project to avoid to write all the fields in $project that could be very tedious.

This happen in $project because if you include specifically a field, the other fields will be automatically excluded.

Example:

{ 
  $addFields: { my_new_id_name: "$_id" }
},
{
  $project: { _id: 0 }
}