Chartkick cumulative chart by date never descending-CodePudding

I have a problem with using a cumulative chart with Chartkick. At the moment, here is how the chart is built in Ruby:

errors = Error.where(status: 'active')
sum = errors.where('first_occurrence_date <= ?', Time.zone.today - 30.days).count    
line_chart errors.group_by_day(:first_occurrence_date, last: 30).count.map { |x,y| { x => (sum  = y)} }.reduce({}, :merge)

I have an external service giving me the errors happening on my Rails app, and I collect them using API calls and store them in a database.

The problem is, these errors can have the status Resolved or Active. On the external platform, I have the possibility to "resolve" the errors when I think I have dealt with the bug. Therefore the status goes from active -> resolved

All these errors have a first occurrence timestamp, on which I'm building my chart. Let's imagine the following scenario:

Monday => 0 errors
Tuesday => 10 errors occurring for the first time 
Wednesday => 2 errors (which occurred on tuesday) resolved (active -> resolved) => total of 8 active errors
Thursday => 4 errors occurring for the first time
Friday => 1 error which occurred on Thursday solved, and 1 on Tuesday solved

My graph will have the following values on Wednesday

Monday => 0
Tuesday => 7
Wednesday => 7
Thursday => 10
Friday => 10

(because I only take the errors which have the active status in my chart)

What I would like would be:

Monday => 0
Tuesday => 10
Wednesday => 8
Thursday => 12
Friday =>10

I have thought a moment about how to do, and can't manage to find a solution, anyone has any idea on how to solve this issue ?

Thanks a lot !

CodePudding user response：

I think it is not possible for cumulative data if you only have first occurred timestamp and current status.

If your errors will never be deleted and the only action is resolve (Change from active -> resolved status), you could add a new field, indicate when the error was resolved.

The error will be considered active on a day if they are created before or on that day, and not resolved or resolved after that day. So you query would be:

# Don't filter by status here
errors = Error.where('first_occurrence_date <= ?', Time.zone.today - 30.days)

day_data = (29.days.ago.to_date..Time.zone.today).to_h { |day| [day, 0] }

errors.find_each do |error|
  resolved_date = error.resolved_at&.to_date || Time.zone.tomorrow
  (error.first_occurrence_date..resolved_date).each do |day|
    day_data[day]  = 1
  end
end

If the error can be reopened/resolved multiple times, can be deleted, or having multiple statuses, this approach will be invalid though. You may consider storing the history amount for each day in a new model via a daily cronjob or something like that, and just query those amounts. For example

Cronjob: run at the end of the day

# first_occurrence_date doesn't matter, we only count the errors still active by the end of the day
DayReport.create(day: Time.zone.today, active_errors_count: Error.where(status: "active").count)

Then simply query for the chart

line_chart DayReport.pluck(:day, :active_errors_count).to_h