RoR, Can't iterate from DateTime/TimeWithZone

问题

I have a simple task where I want to take a starting date and an ending date and loop over the days/dates. This code is being used in my db:seed rake task. Currently, my code has gone through the following attempts.

(someModel.start_date.to_datetime..someModel.end_date.to_datetime).each { 
    |x| puts x 
}
 ......
(someModel.start_date...someModel.end_date).each { |x| puts x }

In each case, I get an error like this.

can't iterate from ActiveSupport::TimeWithZone
or 
can't iterate from DateTime

If anyone has any clue on how to iterate over a range of DateTimes I'd be greatly appreciative.

回答1:

start = someModel.start_date.to_datetime
finish = someModel.end_date.to_datetime
while(start < finish) do
  #bunch of awesome stuff
  start += 1.day
end

回答2:

You must make sure that you are dealing with a Date object (by calling to_date), then everything works as expected:

start_date.to_date.upto(end_date.to_date) {|date| puts date }

Or with a range:

(start_date.to_date..end_date.to_date).to_a

回答3:

You can't iterate from DateTime. But you can iterate when start and end of interval are instances of Date. Convert them if possible.

And then look at these Date methods:

• step()
• upto()
• downto()

to use instead of each

回答4:

If you want to iterate on the range you might consider a loop and step each day using something like someModel.start_date + 1.day.to_i

来源：https://stackoverflow.com/questions/21744683/ror-cant-iterate-from-datetime-timewithzone