mongodb - mongoose node.js, query with $lt and $gt not working -

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i want pupils last mark between 15 , 20. so, perform following query in mongodb using mongoose: models working fine (all other queries ok).

pupils.find({"marks[-1].value": {'$lt' : 20 }, "marks[-1].value" : { '$gt' : 15 }}, function(err, things){

this not working, there missed ?

* update *

i found like:

pupils.find({ "marks[-1].value": {$gt : 15, $lt : 20}});

but not work either. there way last mark of marks array in case ?

lets consider pupils collection:

pupils  {   _id,   marks(integer),   latestmark(int) }

i suggest add latest mark pupil document(as can see @ document above), , update each time when adding new mark nested collection. able query on this:

db.pupils.find({ "latestmark": {$gt : 15, $lt : 20}});

also can query latest mark using $where, care because:

javascript executes more native operators, flexible


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