> db.users.findOne(); { \"_id\" : ObjectId(\"4db8ebb4c693ec0363000001\"), \"fb\" : { \"name\" : { \"last\" : \"Sss\", \"fi
Try this :
User.findOne( { $where : "this.fb.gender == 'male' " } )
or
User.findOne( { fb.gender : "male" } )