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i am working on a problem where in my database there supposed to be multiple entries from day to day.
each entry includes a timestamp. the problem is im supposed to find how many days in each month a data has been entered.
ex: if a user sends a message every 2 days in may. my answer would be: "the user used the message function for 15 days in may".
now if the user sends 5 messages every 2 days in may. the answer would be still 15. im only counting the days the user has been using the app.

using this query:

model.find({ 
    date: {
        $gte: new Date(startOfMonth), 
        $lt: new Date(endOfMonth)
    }
})

i was able to find all data entries on a specific month.
the data may look like something like this:

 Date: dd/mm/yy        Message:
 1/5/2022              "Hello"
 1/5/2022              "World"
 1/5/2022              "!"
 5/5/2022              "Hello World!"
 8/5/2022              "Hello World!"

the desired answer would be 3 unique days in may.

How do i achieve this using mongodb? the simplest answer that come to mind is to use additional queries to group by unique days, but i have no idea how to do that using mongo provided i need to access the date.

2

Answers


  1. You can use distinct
    db.collection.distinct({date:{$gte:new Date(startOfMonth),$lt:new Date(endOfMonth)}}).length
    if you are directly storing the date of it.

    Note : This may not work if you’re storing complete timestamp instead of date.

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  2. This might solves your problem. it will return distinct messages.

    
    Model.aggregate(
        [
            { "$match": {
                "date": { 
                    "$gte": new Date(startOfMonth), "$lt": new Date(endOfMonth)
                }
            }},
            { "$group": {
                "_id": { 
                    "year":  { "$year": "$date" },
                    "month": { "$month": "$date" },
                    "day":   { "$dayOfMonth": "$date" }
                }
                "count": { "$sum": 1 }
            }}
        ],
        function(err,result) {
            // do something with result
    
        }
    );
    
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