I have a collection as follows:

{     "_id" : ObjectId("5a6d9a1ee183f06dfd91dbf0"),     "date" : "20180126",     "oid" : "000",     "aid" : "0000000000",     "currentavalible" : "7",     "deletedbyuser" : "0",     "reply" : [         {             "oidaid" : "000000",             "nickname" : "****",             "date" : "2018-01-26 07:32:45",             "recomm" : "13",             "unrecomm" : "0",             "contents" : "aaaaaaaaaaaa"         },          {             "oidaid" : "000088",             "nickname" : "para****",             "date" : "2018-01-26 08:29:54",             "recomm" : "12",             "unrecomm" : "0",             "contents" : "bbbbbb"         }     ] } 

To find in reply that "recomm" is "13" i tried:

db.comments.find( { 'reply.recomm' : '13' }) db.comments.find( { 'reply' :{ 'recomm' : '13'}  }) db.comments.find( {'_id' :  ObjectId("5a6d9a1ee183f06dfd91dbf0"), 'reply.recomm' : '12' }) db.comments.find( {'_id' :  ObjectId("5a6d9a1ee183f06dfd91dbf0"), 'reply' : { 'recomm' : '12'} }) 

And all fetched me nothing.

What seems to be the error in my syntax?