Finding missing date using aggregation

[Chloe_Gwon (chloe)]

Hello, I’m working on aggregation and bar charts using next.js.
I’m recording my data daily. When the first day of the month has started, I would like to make all dates from 1st to 30th(/31st). Since I’m using bar charts, if there’s only one data, it only shows one bar chart.
And sometimes there’s no data for the day, and I want to fill the gap setting the value of powerIn as 0.
I found $fill and $densify but those won’t work. And I already looked into another question similar as mine that someone recommending making a mock collection or doing it on server side, I found this tricker. Could anyone give me solution on this?

_id:"ABC"
date:"2022-10-01"
powerIn:30

[steevej (Steeve Juneau)]

You may be able to use $range in an aggregation to generate the missing days.

See the following thread for examples specific to using dates.

How project all day between two date?

Initially you said that you were using the date type: But your sample data shows a string "2022-01-10" - now you can convert that to proper ISODate by using $toDate expression, but I’m hoping maybe it’s just a typo and the dates are already stored as dates and not strings. In either case, there are a lot of different ways this can be done, here is one way you can do what you describe (and I’m assuming you want separate documents at the end rather than an array of dates like the original inpu…