{queid:'1',date:'07023/2013',topic: 'topic1'}
{queid:'2',date:'07022/2013',topic: 'topic2'}
{queid:'3',date:'07022/2013',topic: 'topic1'}
{queid:'4',date:'07023/2013',topic: 'topic1'}
que.aggregate([
{$group:{_id:{"topic":"$topic","date":"$date"}, sum:{$sum:1}}},
{$group:{_id:"$_id.topic", "dates":{$push:{"date":"$_id.date", "count":"$sum"}} }}
])
{
"result" : [
{
"_id" : "topic2",
"dates" : [
{ "date" : "07022/2013", "count" : 1}
]
},
{
"_id" : "topic1",
"dates" : [
{ "date" : "07022/2013", "count" : 1},
{ "date" : "07023/2013", "count" : 2}
]
}
],
"ok" : 1
}