How to aggregate count on items that don't match in mongodb

[Bharath Keshav]

Hello,

I have a aggregation query that aggregates total open alerts over a span of last 7 days. My query works - as it retrieves counts in the last two days. However, it does not return a 0 count against those days where there is no data available. How do I go about including them as well?

My current query in run from within nodejs:

alerts.aggregate([{
            $match: {
                "misc.createdTime": {
                    $gt: new Date(weekStart) // 7 days ago
                },
                alertState: alertState,
                alertCategory: {'$regex': alertCategory}
            }
        },
        {
            $group: {
                _id: {
                    $dateToString: {
                        format: "%Y%m%d",
                        date: "$misc.createdTime"
                    }
                },
                count: { $sum: { $cond: [ { $eq: [ "$match", "none" ] }, 0, 1 ] } } // => based on another SO answer, but doesn't seem to work.
                // count: {
                //     $sum: 1
                // }
            }
        },
        {
            $sort: {
                _id: 1
            }
        }
    ]).toArray();

[Oleg Toropov]

Bharath

May be $add will work for you better?

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[Wan Bachtiar]

it does not return a 0 count against those days where there is no data available

Hi Bharath,

Could you elaborate your case further with document examples ?
Especially to define no data available, i.e. do you mean the documents that don’t match the first $match stage ?

Please post both documents, the ones matched and the ones that don’t

Regards,
Wan.

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