MongoDB aggregate query - mongodb

Question

In MongoDB I have a collection:
Statistics
{
UserID: int //User id
Url: string //Url
Clicks: [DateTime] //A time array
}
When a user clicks an url add a date of the click date in Clicks array. My question is how can I write an aggregate query such as get a number of clicks that was from [date1] till [date2] and group by UserID? How can I output the, to a file?
Thanks!

Answer 1

Assuming you have data like this (see at the bottom how to generate this):
{ "_id": ObjectId("508ab0e27bb16229520c9561"), "userid": 0, "url": "", "clickDate": ISODate("20120101T12:01:00Z") }
{ "_id": ObjectId("508ab0e27bb16229520c9562"), "userid": 1, "url": "", "clickDate": ISODate("20120202T12:01:00Z") }
{ "_id": ObjectId("508ab0e27bb16229520c9563"), "userid": 2, "url": "", "clickDate": ISODate("20120303T12:01:00Z") }
{ "_id": ObjectId("508ab0e27bb16229520c9564"), "userid": 3, "url": "", "clickDate": ISODate("20120404T11:01:00Z") }
{ "_id": ObjectId("508ab0e27bb16229520c9565"), "userid": 4, "url": "", "clickDate": ISODate("20120505T11:01:00Z") }
Here is the aggregation function:
db.test.aggregate( {
$match: {
clickDate: { $gte: new Date(2012,8,30,12,0,0) }
}
},
{
$group: {
_id: "$userid",
clicks: { $sum: 1 }
}
}
);
Make sure you have the $match before the $group. See early filtering.
Results:
{
"result": [
{ "_id": 8,
"clicks": 1
},
{ "_id": 7,
"clicks": 2
},
{ "_id": 6,
"clicks": 2
},
{ "_id": 3,
"clicks": 2
},
{ "_id": 2,
"clicks": 2
},
{ "_id": 1,
"clicks": 2
},
{ "_id": 4,
"clicks": 2
},
{ "_id": 0,
"clicks": 2
},
{ "_id": 5,
"clicks": 2
},
{ "_id": 9,
"clicks": 1
}
],
"ok": 1
}
The Data was generated with this loop:
// d=days, m=months (for ISODate months start from 0, while days from 1)
for (var i = 0, d = 1, m = 0, id = 0; i < 100; i++, d++, m++, id++) {
if (d > 30){
d=1;
}
if (m > 10){
m=0;
}
if (id > 9){
id=0;
}
db.test.insert({userid: id, url:"", clickDate: new Date(2012,m,d,12,1,0)});
}