Best way to create random DateTime in Rails

You are using Faker; why not use one of the methods provided by Faker::Date?

# Random date between dates
# Keyword arguments: from, to
Faker::Date.between(from: 2.days.ago, to: Date.today) #=> "Wed, 24 Sep 2014"

# Random date between dates except for certain date
# Keyword arguments: from, to, excepted
Faker::Date.between_except(from: 1.year.ago, to: 1.year.from_now, excepted: Date.today) #=> "Wed, 24 Sep 2014"

# Random date in the future (up to maximum of N days)
# Keyword arguments: days
Faker::Date.forward(days: 23) # => "Fri, 03 Oct 2014"

# Random date in the past (up to maximum of N days)
# Keyword arguments: days
Faker::Date.backward(days: 14) #=> "Fri, 19 Sep 2014"

# Random birthday date (maximum age between 18 and 65)
# Keyword arguments: min_age, max_age
Faker::Date.birthday(min_age: 18, max_age: 65) #=> "Mar, 28 Mar 1986"

# Random date in current year
Faker::Date.in_date_period #=> #<Date: 2019-09-01>

# Random date for range of year 2018 and month 2
# Keyword arguments: year, month
Faker::Date.in_date_period(year: 2018, month: 2) #=> #<Date: 2018-02-26>

# Random date for range of current year and month 2
# Keyword arguments: month
Faker::Date.in_date_period(month: 2) #=> #<Date: 2019-02-26>

current Faker version: 2.11.0

Here is how to create a date in the last 10 years:

rand(10.years).ago

You can also get a date in the future:

rand(10.years).from_now

Update – Rails 4.1+

Rails 4.1 has deprecated the implicit conversion from Numeric => seconds when you call .ago, which the above code depends on. See Rails PR #12389 for more information about this. To avoid a deprecation warning in Rails 4.1 you need to do an explicit conversion to seconds, like so:

rand(10.years).seconds.ago

I prefer use (1..500).to_a.rand.days.ago

Here are set of methods for generating a random integer, amount, time/datetime within a range.

def rand_int(from, to)
  rand_in_range(from, to).to_i
end

def rand_price(from, to)
  rand_in_range(from, to).round(2)
end

def rand_time(from, to=Time.now)
  Time.at(rand_in_range(from.to_f, to.to_f))
end

def rand_in_range(from, to)
  rand * (to - from) + from
end

Now you can make the following calls.

rand_int(60, 75)
# => 61

rand_price(10, 100)
# => 43.84

rand_time(2.days.ago)
# => Mon Mar 08 21:11:56 -0800 2010