I'm trying to notify my customers that their subscription is about to expire. This is how I look for those users to notify them. They will be billed on the date they subscribed + 1.year:
User.where(subscribed_at: 53.weeks.ago.beginning_of_day..53.weeks.ago.beginning_of_day)
My question is will this create issue with leap years? or is there a better way to do this?
Rails provides Time#advance for "precise Time calculations":
Time.now.advance(years: -1, weeks: -1)
#=> 2013-10-08 17:54:36 +0200
Time#all_day returns a whole day's range:
Time.now.advance(years: -1, weeks: -1).all_day
#=> 2013-10-08 00:00:00 +0200..2013-10-08 23:59:59 +0200
I think you should use 1.year.ago since 52.weeks.ago is not equal to a full year (52*7 = 364 days).
The usage of 1.year.ago would be better because it actually changes the year field of the DateTime, nothing else:
1.9.3p489 :005 > 2.year.ago
# => Mon, 15 Oct 2012 11:51:44 EDT -04:00
1.9.3p489 :006 > 5.year.ago
# => Thu, 15 Oct 2009 11:51:47 EDT -04:00
1.9.3p489 :007 > 999.year.ago
# => Sun, 15 Oct 1015 11:51:50 LMT -04:56 # For some reason the TimeZone changed!
In your case, I would use the following logic: NOPE NOPE, I would use #Stefan's answer!
range = (1.year.ago-1.week).beginning_of_day..(1.year.ago-1.week).end_of_day
User.where(subscribed_at: range)
Related
There is task model with attributes when and duration.
create_table "tasks", force: true do |t|
...
t.datetime "when"
t.integer "duration"
...
end
I wrote method for checking if task is active so I can show it on page.
This is active method:
def active?
if (self.when + self.duration) > Time.now
true
end
end
I tried in console to inspect object:
t.when + t.duration
=> Sun, 08 Sep 2013 01:01:00 UTC +00:00
DateTime.now
=> Sun, 08 Sep 2013 01:57:13 +0200
t.active?
=> true
It's true but I entered 1:00 time and 1 minute for duration and I hoped it shouldn't be true.
It seems that when column in database is not saved in correct time zone, so it gives incorrect results. How to solve this issue?
It seems that when column in database is not saved in correct time zone
1) Rails automatically converts times to UTC time before inserting them in the database (which is a good thing), which means the times have an offset of "+0000" . That means if you save a time of 8pm to the database, and your server is located in a timezone with an offset of "+0600", then the equivalent UTC time is 2pm, so 2pm gets saved in the database. In other words, your local server's time is 6 hours ahead of UTC time, which means that when it's 8pm in your server's time zone, it's 2pm in the UTC timezone.
2) When you compare dates, ruby takes the timezone offset into account--in other words ruby converts all times to the same timezone and then compares the times. Here is an example:
2.0.0p247 :086 > x = DateTime.strptime('28-01-2013 08:00:00 PM +6', '%d-%m-%Y %I:%M:%S %p %z')
=> Mon, 28 Jan 2013 20:00:00 +0600
2.0.0p247 :087 > y = DateTime.strptime('28-01-2013 08:20:00 PM +7', '%d-%m-%Y %I:%M:%S %p %z')
=> Mon, 28 Jan 2013 20:20:00 +0700
2.0.0p247 :088 > x < y
=> false
If you just compare the times of the two Datetime objects, x is less than y. However, y has a time of 8:20pm in a timezone that has an offset of +7, which is equivalent to the time 7:20pm in a timezone with an offset of +6. Therefore, y is actually less than x. You need to compare apples to apples, which means you need to mentally compare times that have been converted to the same timezone to get the same results as ruby/rails produces.
3) You can convert Time.now to a UTC time using the rails utc() method:
2.0.0p247 :089 > x = Time.now
=> 2013-09-07 8:00:00 +0600
2.0.0p247 :090 > x.utc
=> 2013-09-07 02:00:00 UTC
That's what ruby does before comparing Time.now to task.when + task.duration
4) You might find it more convenient to create a DateTime object with the time you want using:
DateTime.strptime('28-01-2013 08:00:00 PM +0', '%d-%m-%Y %I:%M:%S %p %z'
Because you are able to specify the offset as zero, you don't have to create a time that anticipates the conversion to UTC time.
Or you can use the change() method, which causes the offset() to change without converting the time:
2.0.0p247 :011 > x = DateTime.now
=> Sun, 08 Sep 2013 00:34:08 +0600
2.0.0p247 :012 > x.change offset: "+0000"
=> Sun, 08 Sep 2013 00:34:08 +0000
ActiveRecord stores timestamps in UTC by default. See How to change default timezone for Active Record in Rails? for changing default time zone.
You can also just use Time#in_time_zone to convert t.when to your timezone, see http://api.rubyonrails.org/classes/ActiveSupport/TimeWithZone.html.
Here goes :
Time.zone.now => "Eastern Time (US & Canada)"
Time.zone.now => Wed, 15 Aug 2012 06:05:37 EDT -04:00
Time.zone.now + 39.years => Tue, 15 Aug 2051 06:06:03 EST -05:00
And so you have it, the end of our fabled Eastern Daylight Time has been prophesied by Ruby on Rails to end in the year 2051.
Also works for any other TimeZone changing area.
Time.zone
=> "Pacific Time (US & Canada)"
1.9.2p180 :003 > Time.zone.now
=> Wed, 15 Aug 2012 03:08:57 PDT -07:00
1.9.2p180 :004 > Time.zone.now + 39.years
=> Tue, 15 Aug 2051 03:08:57 PST -08:00
This exists in Rails 3.0 and in Rails 3.2.6
Yes, it looks like a bug. It's not Rails, however, it's the Ruby Time class. It has problems with times after 2038.
For example, with Ruby 1.8.7:
> Time.local(2037,8,16,9,30,15)
=> Sun Aug 16 09:30:15 -0400 2037
>
> Time.local(2038,8,16,9,30,15)
=> Mon Aug 16 09:30:15 -0500 2038
JRuby 1.6.7.2 - for instance - does not have this problem:
> Time.local(2038,8,16,9,30,15)
=> Mon Aug 16 09:30:15 -0400 2038
Note that, on MRI Ruby on 64-bit systems, the ActiveSupport time extension which supports the addition of durations ultimately calls Time.local or Time.utc via this method in active_support/core_ext/time/calculations.rb:
# Returns a new Time if requested year can be accommodated by Ruby's Time class
# (i.e., if year is within either 1970..2038 or 1902..2038, depending on system architecture);
# otherwise returns a DateTime
def time_with_datetime_fallback(utc_or_local, year, month=1, day=1, hour=0, min=0, sec=0, usec=0)
::Time.send(utc_or_local, year, month, day, hour, min, sec, usec)
rescue
offset = utc_or_local.to_sym == :local ? ::DateTime.local_offset : 0
::DateTime.civil(year, month, day, hour, min, sec, offset)
end
I guess the issue is that for years >= 2038, they were expecting an overflow exception and for DateTime to be used instead. On 64-bit systems, this doesn't happen.
UPDATE: This analysis is incorrect for Ruby 1.9.2+. Time.local works as expected, but the original problem still occurs.
I would expect Time and to_time to be reflective.
UPDATE
This is the answer, if you add the parameter :local, it doesn't ignore the offset. I find it wierd that it ignores data (the offset) by default, though...
Time.zone.now.to_s.to_time(:local) returns 2012-03-20 14:39:03 +0100
/UPDATE
> Time.zone.now.to_s
=> "2012-03-20 12:50:05 +0100"
> Time.zone.now.to_s.to_time.to_s
=> "2012-03-20 12:50:05 UTC"
# PROBLEM:
# UTC is +0000, meaning that there is 1 hour diff in the above
> Time.zone.now
=> Tue, 20 Mar 2012 12:51:32 CET +01:00
> Time.zone.now.to_time
=> Tue, 20 Mar 2012 12:51:32 CET +01:00
> Time.zone.now.to_json
=> "\"2012-03-20T12:50:36+01:00\""
> Time.zone.now.to_json.to_time
=> 2012-03-20 12:50:36 UTC
I have this problem with JSON messages. Anyway, I wouldn't expect to_time to actually change the time. OK to translate to UTC, probably, but it should adjust time accordingly. Anybody know if this is a known issue or "by design"?
This method, String#to_time, defined in ActiveSupport takes one parameter, form, which can be either :utc (default) or :local. So by default, it always returns a Time in UTC.
To get a Time with timezone:
Time.zone.parse("2012-03-20T12:50:36+01:00")
I have a DateTime object representing a particular date, as in "2011-01-15 00:00:00 UTC" to represent January 15th. I would like to produce the range of times in a particular time zone that have the same date.
The method signature would probably be something like
def day_range_for(date, tz)
# ...
end
For example, if I have range_for(DateTime.parse('2011-01-15'), 'CST'), then I want the result to be a range like 2011-01-15 00:00:00 -0600 .. 2011-01-15 23:59:59 -0600.
Can you take the input string instead of the object? If you pass in a DateTime object, its a tad counter intuitive because the time the object represents isn't the actual time you are looking for. It would conform to my expectations if you either passed in the correct, absolute DateTime, or the string itself. The actual meat of the problem is entirely handled by ActiveSupport, which I think you are using since you tagged this question with Rails. How does this look?
def range_for(input, tz=nil)
if tz.is_a?(String)
tz = ActiveSupport::TimeZone.new(tz)
else
tz = Time.zone
end
if input.acts_like?(:date) || input.acts_like?(:time)
d = input.in_time_zone(tz)
else
d = tz.parse(input)
end
return d.beginning_of_day..d.end_of_day
end
Have a look:
ruby-1.9.2-p0 > range_for('2011-01-15', 'Alaska')
=> Sat, 15 Jan 2011 00:00:00 AKST -09:00..Sat, 15 Jan 2011 23:59:59 AKST -09:00
ruby-1.9.2-p0 > range_for(Time.zone.now)
=> Mon, 10 Jan 2011 00:00:00 EST -05:00..Mon, 10 Jan 2011 23:59:59 EST -05:00
ruby-1.9.2-p0 > range_for('2011-01-15', 'EST')
=> Sat, 15 Jan 2011 00:00:00 EST -05:00..Sat, 15 Jan 2011 23:59:59 EST -05:00
How about:
def day_range_for date, zone
(DateTime.new(date.year,date.month,date.day,0,0,0,zone)..DateTime.new(date.year,date.month,date.day,23,59,59,zone))
end
day_range_for(DateTime.parse('2011-01-15'), 'CST')
#=> #<DateTime: 2011-01-15T00:00:00-06:00 (9822307/4,-1/4,2299161)>..#<DateTime: 2011-01-15T23:59:59-06:00 (212161917599/86400,-1/4,2299161)>
I was wondering if there's a way in Rails to calculate time stamp like - half a minute ago, 2 minute ago, 1 day ago etc. Something like twitter real time date stamp.
I want to know if Ruby/Rails has a built-in function for such date-time conversion?
You can use:
10.minutes.ago
2.days.since
Or in your views you have the helpers:
distance_of_time_in_words(from_time, to_time)
time_ago_in_words(from_time)
Check the API for details and more options.
You can use available methods to get the time in past or future using ago, since alias for from_now and many available methods
Time.current
#=> Tue, 20 Sep 2016 15:03:30 UTC +00:00
2.minutes.ago
#=> Tue, 20 Sep 2016 15:01:30 UTC +00:00
2.minutes.since
#=> Tue, 20 Sep 2016 15:05:30 UTC +00:00
1.month.ago
#=> Sat, 20 Aug 2016 15:03:30 UTC +00:00
1.year.since
#=> Wed, 20 Sep 2017 15:03:30 UTC +00:00
Check all the available methods in Time class
distance_of_time_in_words:
from_time = Time.now
distance_of_time_in_words(from_time, from_time + 50.minutes) # => about 1 hour
distance_of_time_in_words(from_time, 50.minutes.from_now) # => about 1 hour
distance_of_time_in_words(from_time, from_time + 15.seconds) # => less than a minute
distance_of_time_in_words(from_time, from_time + 15.seconds, include_seconds: true) # => less than 20 seconds
time_ago_in_words:
time_ago_in_words(3.minutes.from_now) # => 3 minutes
time_ago_in_words(3.minutes.ago) # => 3 minutes
time_ago_in_words(Time.now - 15.hours) # => about 15 hours