group_by relative date ranges

I have a client who wants to see a report of her employees grouped by the date they took their last position (date_in_position). She wants them grouped by: Less than 1 year, 1-3 years, 3-5 years, and over 5 years. I made a little method to return a string usable for the group_by method, but only "less than 1 year" is working correctly. Everything else shows up as over 5 years.

def dip_range
  case self.date_in_position
    when 1.year.ago...Date.today
      '<开发者_运维技巧; 1 year'
    when 3.years.ago...(1.year.ago + 1)
      '1-3 years'
    when 5.years.ago...(3.years.ago + 1)
      '3-5 years'
    else 
      '> 5 years'
  end
end

another way to approach it:

def dip_range
  case
    when self.date_in_position.between?(1.year.ago,Date.today)
      '< 1 year'
    when self.date_in_position.between?(3.years.ago,(1.year.ago + 1))
      '1-3 years'
    when self.date_in_position.between?(5.years.ago,(3.years.ago + 1))
      '3-5 years'
    else 
      '> 5 years'
  end
end

In R1.8 (Time..Date) range doesn't work at all, besides I would rewrite this piece of code anyway:

# self is not required by the way
case (Date.today - date_in_position) / 365.2425 
when (0...1)
  '< 1 year'
when (1...3)
  '< 3 years'
when (3...5)
  '< 5 years'
else
  '> 5 year'
end

Or even:

years = (Date.today - date_in_position) / 365.2425
case  
when years < 1
  '< 1 year'
when years < 3
  '< 3 years'
when years < 5
  '< 5 years'
else
  '> 5 year'
end

Integer#years.ago returns a DateTime which isn't comparing properly to the Date objects you are switching on. I'm not exactly sure why this is, but if you change

case self.date_in_position

to case self.date_in_position.to_datetime

this code will work for most cases.

Also, your bounds are incorrect. If someone started work 1 year ago today, they should show as 1-3 years, right? So:

def dip_range
  case self.date_in_position
    when (1.year.ago+1.day).to_date..Date.today
      '< 1 year'
    when (3.years.ago+1.day).to_date..1.year.ago.to_date
      '1-3 years'
    when (5.years.ago.to_date+1.day).to_date..3.years.ago.to_date
      '3-5 years'
    else 
      '> 5 years'
  end
end

I think this is what you want because it will match in order of priority, change the syntax if you like:

def dip_range
  t = self.date_in_position
  if t > 1.year.ago
    '< 1 year'
  elsif t > 3.years.ago
    '1-3 years'
  elsif t > 5.years.ago
    '3-5 years'
  else 
    '> 5 years'
  end
end