Active Record order by current day - ruby-on-rails

Question

Im having an issue sorting an array by the current date.
my database has a field called day
day has the days of the week eg: Monday, Tuesday, etc.
I am trying to sort my index view page by the current day.
I would like to do somehting like this in my controller,
#happies = Happy.where(id: #search.results.map(&:id))
.page(params[:page])
.where(:day => Date.today.strftime('%A').capitalize.to_s)
but instead of returning only happies with the day Monday I would want to order by day where day is equal to the current day.
I also thought about doing this in my view
with something like
<% #happies.sort_by(:day => Date.today.strftime('%A').capitalize.to_s).each do |happy| %>
the above does not work but im trying to get accross what I wan to achieve. Any ideas on how to implement this?
Maybe there is an activeview helper?

Answer 1

If you were not paginating, you could sort the results in plain ruby like this:
day_order = %w(Tuesday Wednesday Thursday Friday Saturday Sunday Monday)
#happies = #happies.sort_by{|happy| day_order.index(happy.day)}
sort_by takes a block that returns the value to sort by.
However, you appear to be paginating using will_paginate. That's fine but it makes things more complicated.
The pagination necessarily happens in the database via limit and offset (so as to avoid returning the entire contents of the table to the Rails process). Therefore you want the sorting to also happen in the database. If you were to sort in ruby (as above) you would be sorting after pagination, meaning the first page would give you essentially random results, and then you'd sort them. Probably not what you want.
Long story short, you probably want to use order instead of sort_by, and I'm going to have to dip into SQL for this one:
#happies = Happy.where(id: #search.results.map(&:id))
.page(params[:page])
.order("CASE day WHEN 'Tuesday' THEN 0 " \
"WHEN 'Wednesday' THEN 1 " \
"WHEN 'Thursday' THEN 2 " \
"WHEN 'Friday' THEN 3 " \
"WHEN 'Saturday' THEN 4 " \
"WHEN 'Sunday' THEN 5 " \
"WHEN 'Monday' THEN 6 END")
If you want to avoid SQL, perhaps it is possible to use Arel for this, I'm not sure.
Edit
I see now you want to start with the current day, i.e. not hardcoded as Tuesday like I did. To fix my SQL version - and borrowing a bit from #Snarf's answer - you could do this:
days = %w(Monday Tuesday Wednesday Thursday Friday Saturday Sunday)
days.rotate!(days.index(Time.zone.now.strftime("%A")))
case_pieces = days.each_with_index.map do |day, i|
"WHEN '#{day}' THEN #{i}"
end
#happies = Happy.where(id: #search.results.map(&:id))
.page(params[:page])
.order("CASE day #{case_pieces.join(' ')} END")
Another thought
If I was writing the app myself, I would be tempted to store the day as an integer from 0 to 6, instead of as a string. Then you could order using the modulo operator, something like this:
days = %w(Monday Tuesday Wednesday Thursday Friday Saturday Sunday)
day_offset = days.index(Time.zone.now.strftime("%A"))
#happies = Happy.where(id: #search.results.map(&:id))
.page(params[:page])
.order("(day - #{day_offset} + 7) % 7")

Answer 2

Here's a pure ruby solution.
days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]
days.rotate(days.index(Time.now.strftime("%A")))
#=> ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]

Answer 3

Basically the same as #Snarf - this is only ruby and will not support pagination
today = Date.current.strftime('%A')
# => Monday
days = Date::DAYNAMES
# => ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]
today_index = days.index(today)
# => 1
#ordered_days = days.rotate(today_index)
# => ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]
#happies = Happy.where(id: #search.results)
<!-- view -->
<% #ordered_days.each do |day| %>
<!-- in memory selection from the #happies collection, could be emtpy -->
<% occurring_on = #happies.select { |happy| happy.day == day } %>
<%= day %>
<% occuring_on.each do |happy| %>
<%= happy %>
<% end %>
<% end %>