How to get all subfields of mongodb in a query when one field is root field of other field requested?

Question

For this specific case, everything works fine, except when for the fields field1,field2 requested, and field1 is a part of field2.

Example :

> db.mycoll.findOne()
{
    "_id" : 1,
    "data" : {
        "amounts" : {
            "dollar" : 20,
            "euro" : 18
        },
        "item" : "toy",
        "sale" : false
    }
}

   // works well
> db.mycoll.findOne({"_id":1},{ "data.amounts.dollar":1 })
{ "_id" : 1, "data" : { "amounts" : { "dollar" : 20 } } }



   // here "data" is root of "data.amounts.dollar" and "data.amounts.euro" 
   //   takes preference, how to query for "data", so 
   //   that all subfields of data are 
   //     returned
> db.mycoll.findOne({"_id":1},{ "data":1 , "data.amounts.dollar":1 })
{ "_id" : 1, "data" : { "amounts" : { "dollar" : 20 } } }

Expected output :

 {
        "_id" : 1,
        "data" : {
            "amounts" : {
                "dollar" : 20,
                "euro" : 18
            },
            "item" : "toy",
            "sale" : false
        }
    }

Yes, it is possible to format the subfields on the program side, and send the root field to mongodb query, but my question is if this is feasible on the querying side without Javascript .

Answer 1

This is unusual behavior, a bug to be precise.

From credible/official sources :

• Jira Open Bug
• Jira Bug Duplicate

Seems that the bug is still open.

Please let me know if you need any further analysis.

Answer 2

db.mycoll.findOne({"_id":1},{"data.amounts.dollar":1,"data":1 })