In MongoDB mapreduce, how can I flatten the values object?

Question

I'm trying to use MongoDB to analyse Apache log files. I've created a receipts collection from the Apache access logs. Here's an abridged summary of what my models look like:

db.receipts.findOne()
{
    "_id" : ObjectId("4e57908c7a044a30dc03a888"),
    "path" : "/videos/1/show_invisibles.m4v",
    "issued_at" : ISODate("2011-04-08T00:00:00Z"),
    "status" : "200"
}

I've written a MapReduce function that groups all data by the issued_at date field. It summarizes the total number of requests, and provides a breakdown of the number of requests for each unique path. Here's an example of what the output looks like:

db.daily_hits_by_path.findOne()
{
    "_id" : ISODate("2011-04-08T00:00:00Z"),
    "value" : {
        "count" : 6,
        "paths" : {
            "/videos/1/show_invisibles.m4v" : {
                "count" : 2
            },
            "/videos/1/show_invisibles.ogv" : {
                "count" : 3
            },
            "/videos/6/buffers_listed_and_hidden.ogv" : {
                "count" : 1
            }
        }
    }
}

How can I make the output look like this instead:

{
    "_id" : ISODate("2011-04-08T00:00:00Z"),
    "count" : 6,
    "paths" : {
        "/videos/1/show_invisibles.m4v" : {
            "count" : 2
        },
        "/videos/1/show_invisibles.ogv" : {
            "count" : 3
        },
        "/videos/6/buffers_listed_and_hidden.ogv" : {
            "count" : 1
        }
    }
}

Answer 1

It's not currently possible, but I would suggest voting for this case: https://jira.mongodb.org/browse/SERVER-2517.