javascript - how to query nested JSON using mongodb -

i have json this:

"marks":{     "sem1" :{         "mark1":10,         "total":100     },     "sem2":{         "mark2":20,         "total":200     },     "sem3":{         "mark2":30,         "total":300     } } 

i need result

mark  total   sem  10    100     sem1  20    200     sem2   30    300     sem3 

how can achieve above format using monogodb query.query jaspersoft related means useful.

this not structure if not in control need mapreduce javascript processing:

db.collection.mapreduce(     function () {       var doc = this,           marks = doc.marks;        object.keys( marks ).foreach(function(key) {         //emit( key, doc["marks"][key] );         var matched = object.keys( marks[key] ).filter(function(inner) {           return inner.match(/^mark/);         });          if ( matched.length > 0 ) {           //emit( matched[0], 1 );           var mymatched = matched[0];           emit(             marks[key][mymatched], {               total: marks[key].total,               sem: key             }           );         }       });     },     function() {}, // null reducer not required     { "out": { "inline": 1 } } ); 

not desired result, way mapreduce it. required because structure cannot queried or analysed traditional means.

to better need instead:

{     "marks": [         { "semester": "sem1", "mark": 10, "total": 100 },         { "semester": "sem2", "mark": 20, "total": 200 },         { "semester": "sem3", "mark": 30, "total": 300 }     ] } 

then query aggregation framework, better uses native code , not javascript notation traverse:

db.collection.aggregate([     { "$unwind": "$marks" },     { "$project": {         "mark": "$marks.mark",         "total": "$marks.total",         "sem": "$marks.semester"     }} ]) 

you can more, debatable on sample given want achieve.