$returnKey

  • $returnKey

Deprecated since v3.2

Starting in v3.2, the $returnKey operator is deprecated in themongo shell. In the mongo shell,use cursor.returnKey() instead.

Only return the index field or fields for the results of the query. If$returnKey is set to true and the query does not usean index to perform the read operation, the returned documents willnot contain any fields. Use one of the following forms:

  1. db.collection.find( { <query> } )._addSpecial( "$returnKey", true )
  2. db.collection.find( { $query: { <query> }, $returnKey: true } )