UTC conversion is different between local and server - ruby-on-rails

Question

I am building a Rails 5 app.
In this app I have a query that checks if an Event is already in the database. This works perfectly locally but not on the server. The problem, as I see it is that I convert the date I want to check into UTC and then do the query. The strange thing is that the output of the conversion is different between local and server for the exact same date.
This is the query
scope :available_holidays, -> (date) { where("events.starts_at > ? AND events.starts_at < ? AND ttype = ?", date.beginning_of_day, date.end_of_day, TYPE_NATIONAL) }
This is how I convert to UTC
Time.parse(holiday[:date].to_s).utc
This is the output locally
2017-12-31 00:00:00
This is the output on the server
2018-01-01 00:00:00
This is my method in the controller
def holidays
output = []
from = Date.civil(params["year"].to_i,1,1)
to = Date.civil(params["year"].to_i,12,31)
holidays = Holidays.between(from, to, params["country"])
holidays.each do |holiday|
date = Time.parse(holiday[:date].to_s).utc
event = Event.available_holidays(date).count
if event == 0
output.push(holiday)
end
end
render json: output.to_json
end
What is going wrong?

Answer 1

I see a number of possible problems.
holidays.each do |holiday|
date = Time.parse(holiday[:date].to_s).utc
Why is Holidays.between returning hashes rather than objects?
Why is holiday[:date] a string and not a Date object?
Why is a date being parsed with Time.parse?
Why are time zones involved with a date?
The first two are structural problems. The second two I think are the real problems. Dates don't have time zones.
When you run, for example, Time.parse("2018-05-06") Ruby will return a Time for midnight at that date with a time zone. For example...
> Time.parse("2018-01-01")
=> 2018-01-01 00:00:00 -0800
> Time.parse("2018-01-01").utc
=> 2018-01-01 08:00:00 UTC
As a Date that's 2018-01-01 so no harm. But if you were in +0100...
> Time.parse("2018-01-01 00:00:00 +0100").utc
=> 2017-12-31 23:00:00 UTC
As a Date that's 2017-12-31.
Don't convert dates to times and back to dates. Just keep them as dates.
holidays.each do |holiday|
date = Date.parse(holiday[:date])
Better yet, have Holidays store holiday[:date] as a Date object.