I have a date in Mongoid user collection field dob.
I want to get those users whose age is between 18-30.
but i don't know how to get age from date in Mongoid.
here is the query:
User.in(gender: gender_group).between(dob: 18..30)
Considering a user is 30 years old if he has not yet celebrated his 31st birthday, following would be your logic:
today = Date.today
=> Mon, 07 May 2018
aged_30 = today - 31.years + 1.day
=> Fri, 08 May 1987
aged_18 = today - 18.years
=> Sun, 07 May 2000
User.in(gender: gender_group).between(dob: aged_30..aged_18)
Related
I am creating a range for each month in my example range.
example_range = (Time.zone.today..2.years.from_now)
Output should look like so:
=> [Wed, 03 Aug 2016..Wed, 31 Aug 2016, Thu, 01 Sep 2016..Fri,
30 Sep 2016, Sat, 01 Oct 2016..Mon, 03 Oct 2016, ...]
At the moment I'm doing this, which doesn't work for ranges longer than a year, because the grouping will put January '16 and January '17 in one group.
example_range.group_by(&:month).each { |_, month| month.first..month.last }
I also tried this, but ruby segfaults on this for some reason...
example_range.group_by(&:year).map{ |ary| ary.group_by(&:month)}
Does anyone know a more beautiful (or at least working) way of doing this?
How is this:
example_range.group_by {|date| [date.year, date.month] }.map {|_, month| month.first..month.last }
If you are using Active Support (Rails), this will also work:
example_range.group_by(&:beginning_of_month).map {|_, month| month.first..month.last }
The best solution I think is this:
example_range.group_by {|date| date.month.to_s + "-" + date.year.to_s}
You can adjust the way you need.
How does someone get the name of the day from Date.today?
The below should be equal too "Fri" or "Friday":
Date.today #=> Fri, 20 Nov 2015
Use the following:
Date.today.strftime("%A")
I would like to know how to get the current week number from Rails and how do I manipulate it:
Translate the week number into date.
Make an interval based on week number.
Thanks.
Use strftime:
%U - Week number of the year. The week starts with Sunday. (00..53)
%W - Week number of the year. The week starts with Monday. (00..53)
Time.now.strftime("%U").to_i # 43
# Or...
Date.today.strftime("%U").to_i # 43
If you want to add 43 weeks (or days,years,minutes, etc...) to a date, you can use 43.weeks, provided by ActiveSupport:
irb(main):001:0> 43.weeks
=> 301 days
irb(main):002:0> Date.today + 43.weeks
=> Thu, 22 Aug 2013
irb(main):003:0> Date.today + 10.days
=> Sun, 04 Nov 2012
irb(main):004:0> Date.today + 1.years # or 1.year
=> Fri, 25 Oct 2013
irb(main):005:0> Date.today + 5.months
=> Mon, 25 Mar 2013
You are going to want to stay away from strftime("%U") and "%W".
Instead, use Date.cweek.
The problem is, if you ever want to take a week number and convert it to a date, strftime won't give you a value that you can pass back to Date.commercial.
Date.commercial expects a range of values that are 1 based.
Date.strftime("%U|%W") returns a value that is 0 based. You would think you could just +1 it and it would be fine. The problem will hit you at the end of a year when there are 53 weeks. (Like what just happened...)
For example, let's look at the end of Dec 2015 and the results from your two options for getting a week number:
Date.parse("2015-12-31").strftime("%W") = 52
Date.parse("2015-12-31").cweek = 53
Now, let's look at converting that week number to a date...
Date.commercial(2015, 52, 1) = Mon, 21 Dec 2015
Date.commercial(2015, 53, 1) = Mon, 28 Dec 2015
If you blindly just +1 the value you pass to Date.commercial, you'll end up with an invalid date in other situations:
For example, December 2014:
Date.commercial(2014, 53, 1) = ArgumentError: invalid date
If you ever have to convert that week number back to a date, the only surefire way is to use Date.cweek.
date.commercial([cwyear=-4712[, cweek=1[, cwday=1[, start=Date::ITALY]]]]) → date
Creates a date object denoting the given week date.
The week and the day of week should be a negative
or a positive number (as a relative week/day from the end of year/week when negative).
They should not be zero.
For the interval
require 'date'
def week_dates( week_num )
year = Time.now.year
week_start = Date.commercial( year, week_num, 1 )
week_end = Date.commercial( year, week_num, 7 )
week_start.strftime( "%m/%d/%y" ) + ' - ' + week_end.strftime("%m/%d/%y" )
end
puts week_dates(22)
EG: Input (Week Number): 22
Output: 06/12/08 - 06/19/08
credit: Siep Korteling http://www.ruby-forum.com/topic/125140
Date#cweek seems to get the ISO-8601 week number (a Monday-based week) like %V in strftime (mentioned by #Robban in a comment).
For example, the Monday and the Sunday of the week I'm writing this:
[ Date.new(2015, 7, 13), Date.new(2015, 7, 19) ].map { |date|
date.strftime("U: %U - W: %W - V: %V - cweek: #{date.cweek}")
}
# => ["U: 28 - W: 28 - V: 29 - cweek: 29", "U: 29 - W: 28 - V: 29 - cweek: 29"]
Simple question, but I can't find a good or definitive answer. What is the best and most efficient way to combine Ruby Date and Time objects (objects, not strings) into a single DateTime object?
I found this, but it's not as elegant you would hope:
d = Date.new(2012, 8, 29)
t = Time.now
dt = DateTime.new(d.year, d.month, d.day, t.hour, t.min, t.sec, t.zone)
By the way, the ruby Time object also stores a year, month, and day, so you would be throwing that away when you create the DateTime.
When using seconds_since_midnight, changes in daylight savings time can lead to unexpected results.
Time.zone = 'America/Chicago'
t = Time.zone.parse('07:00').seconds_since_midnight.seconds
d1 = Time.zone.parse('2016-11-06').to_date # Fall back
d2 = Time.zone.parse('2016-11-07').to_date # Normal day
d3 = Time.zone.parse('2017-03-12').to_date # Spring forward
d1 + t
#=> Sun, 06 Nov 2016 06:00:00 CST -06:00
d2 + t
#=> Mon, 07 Nov 2016 07:00:00 CST -06:00
d3 + t
#=> Sun, 12 Mar 2017 08:00:00 CDT -05:00
Here's an alternative, similar to #selva-raj's answer above, using string interpolation, strftime, and parse. %F is equal to %Y-%m-%d and %T is equal to %H:%M:%S.
Time.zone = 'America/Chicago'
t = Time.zone.parse('07:00')
d1 = Time.zone.parse('2016-11-06').to_date # Fall back
d2 = Time.zone.parse('2016-11-07').to_date # Normal day
d3 = Time.zone.parse('2017-03-12').to_date # Spring forward
Time.zone.parse("#{d1.strftime('%F')} #{t.strftime('%T')}")
#=> Sun, 06 Nov 2016 07:00:00 CST -06:00
Time.zone.parse("#{d2.strftime('%F')} #{t.strftime('%T')}")
#=> Sun, 07 Nov 2016 07:00:00 CST -06:00
Time.zone.parse("#{d3.strftime('%F')} #{t.strftime('%T')}")
#=> Sun, 12 Mar 2017 07:00:00 CDT -05:00
Simple:
Date.new(2015, 2, 10).to_datetime + Time.parse("16:30").seconds_since_midnight.seconds
# => Object: Tue, 10 Feb 2015 16:30:00 +0000
You gotta love Ruby!
If using Rails, try any of these:
d = Date.new(2014, 3, 1)
t = Time.parse("16:30")
dt = d + t.seconds_since_midnight.seconds
# => ActiveSupport::TimeWithZone
dt = (d + t.seconds_since_midnight.seconds).to_datetime
# => DateTime
dt = DateTime.new(d.year, d.month, d.day, t.hour, t.min, t.sec)
# => DateTime
If you are using Ruby on Rails, this works great.
I built a method to extend the DateTime class to combine a date and a time. It takes the zone from the date so that it does not end up an hour off with daylight savings time.
Also, for convenience, I like being able to pass in strings as well.
class DateTime
def self.combine(d, t)
# pass in a date and time or strings
d = Date.parse(d) if d.is_a? String
t = Time.zone.parse(t) if t.is_a? String
# + 12 hours to make sure we are in the right zone
# (eg. PST and PDT switch at 2am)
zone = (Time.zone.parse(d.strftime("%Y-%m-%d")) + 12.hours ).zone
new(d.year, d.month, d.day, t.hour, t.min, t.sec, zone)
end
end
So you can do:
DateTime.combine(3.weeks.ago, "9am")
or
DateTime.combine("2015-3-26", Time.current)
etc...
I found another way, I hope this is correct.
datetojoin=Time.parse(datetime).strftime("%Y-%m-%d")
timetojoin=Time.parse(time).strftime("%T")
joined_datetime = Time.parse(datetojoin +" "+ timetojoin).strftime("%F %T")
Any thoughts? Please share.
In Ruby 1.8.7, how to set the time zone of a time?
In the following examples, my system time zone is PST (-8:00 hours from UTC)
Given a time (21 Feb 2011, 20:45), presume that the time is in EST:
#this interprets the time as system time zone, i.e. PST
Time.local(2011,02,21,20,45)
#=> Mon Feb 21 20:45:00 -0800 2011
#this **converts** the time into EST, which is wrong!
Time.local(2011,02,21,20,45).in_time_zone "Eastern Time (US & Canada)"
#=> Mon, 21 Feb 2011 23:45:00 EST -05:00
But, the output I want is:
Mon Feb 21 20:45:00 -0500 2011 (Note the -0500 (EST) as opposed to -0800 (PST) and the hour is same, i.e. 20, not 23)
UPDATE (see the better version of this below)
I managed to get this to work, but I don't like it:
DateTime.new(2011,02,21,20,45).change :offset => -(300.0 / 1440.0)
# => Mon, 21 Feb 2011 20:45:00 +0500
Where
300 = 5 hrs x 60 minutes
1440 = number of minutes in a day
or the "right" way:
DateTime.civil(2011,02,21,20,45,0,Rational(-5, 24))
Question: Now, is there a way to determine the accurate(i.e. catering for daylight saving time etc) UTC offset from Time.zone so that I can pass it to the change method?
Reference: DateTime::change method
UPDATE (better version)
Thanks to #ctcherry for all the help!
Determine the accurate time zone info from Time.zone:
DateTime.civil(2011,02,21,20,45,0,Rational((Time.zone.tzinfo.current_period.utc_offset / 3600), 24))
In ruby 1.8.7 it doesn't appear to be very easy to do what are asking for according to the documentation:
http://www.ruby-doc.org/core-1.8.7/classes/Time.html
However in 1.9 it looks a lot easier by passing the timezone offset to the localtime() method on a Time object:
http://www.ruby-doc.org/core/classes/Time.html#M000346
UPDATE
The offset for Time.zone is easy since its an object on its own: (This is in a Rails console)
ruby-1.8.7-p248 :001 > Time.zone
=> #<ActiveSupport::TimeZone:0x103150190 #current_period=nil, #name="Central Time (US & Canada)", #tzinfo=#<TZInfo::TimezoneProxy: America/Chicago>, #utc_offset=nil>
ruby-1.8.7-p248 :002 > Time.zone.utc_offset
=> -21600
ruby-1.8.7-p248 :003 > Time.zone.formatted_offset
=> "-06:00"
So I think this will (almost) accomplish what you want:
require 'time'
t = "21 Feb 2011, 20:45"
Time.parse(t) # => Mon Feb 21 20:45:00 -0700 2011
t += " -05:00" # this is the trick
Time.parse(t) # => Mon Feb 21 18:45:00 -0700 2011
It still returns the time based on your system time zone, but the actual time is the correct time that you are seeking.
By the way, this is tested on 1.8.7-p334.