ruby on rails - How to sum fields after group_by -

i need group records date, sum 1 field each of days.

this code i'm trying refactor:

<% @startdate.upto(@enddate) |date| %>   <% visitors = @links.where("created_at >= ? , created_at < ?", date, date+1).order("created_at asc").select("id, visit_count") %>   <%= datevisitors.sum("visit_count") || 0 %> <% end %> 

i've started with:

<% visitors = @links.select("visit_count, created_at").group_by{|l| l.created_at.day} %> <% @startdate.upto(@enddate) |date| %>   <%= visitors[date] ...? <% end %> 

when group_by something, receive array of day , element. if group day, you'll have day , elements part of array:

<% @links.group_by{|l| l.created_at.day}.each |day, links| %>   <p><%= day %>: <%= links.sum(&:visit_count) %></p> <% end %> 

edit --

ok, in case code looks close:

<% visitors = @links.select("visit_count, created_at").group_by{|l| l.created_at.day} %> <% @startdate.upto(@enddate) |date| %>   <% if visitors[date] %>     <%= visitors[date].sum(&:visit_count) %>   <% else %>     0   <% end %> <% end %> 

it's better move helper (or presenter)

def daily_visits(links, from, to)   links_by_day = links.select("visit_count, created_at").group_by{|l| l.created_at.day}   range = from.upto(to).to_a   range.inject({}) |date, hash|     hash[date] = links_by_day.fetch(date, 0)   end end 

then, in view:

<% daily_visits(@links, @startdate, @enddate).each |day, count| %>   <%= day %>: <%= count %> <% end %>