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databasemongodbisodate

How to access minutes of isodate field mongodb

I have a mongodb database where each row of the document has a date field (format ISO date).

I am trying to access hours and minutes in the date field and, for each minute of each hour, show the number of rows (notice that can be multiple rows for a minute). The output would be something like this:

11:20   5
11:41   1
13:20   8
15:30   11

Where the first column is the time (hour:minutes), and the second column the number of rows corresponding that time.

This is the command I am executing in mongodb:

db.user.aggregate([{$group: {_id: {hora: {$hour: '$created_at'}, minuto: {$minute: '$created_at'}}, total: {$sum: 1}}}])

where 'hora' is the field showing the hour and 'minuto' the field showing minutes.

This is the message I get:

enter image description here

This is how the isodate format looks: enter image description here

Solution

  • It looks like you are not storing the date as ISODate, but rather as a string with ISODate format.

    When you run the find query, it should be showing
    "created_at" : ISODate("2016-11-01T11:46:03.000Z")

    and not:

    "created_at" : "2016-11-01T11:46:03.000Z"

    The code you have written is correct.

    You will need to convert your strings to ISODates.

    You can fire this query in your mongoshell:

    db.user.find().forEach(function(doc){
    doc.created_at = new Date(created_at)
    db.user.save(doc);
})