Getting count of elements by `created_at` by day in a given month

Question

I wanted to make a simple chart of users that have been created in the past month in my app. Like basically for each day in the past month I want to show the count of users that have registered that day. What I have so far:

# Controller
@users = User.count(:order => 'DATE(created_at) DESC', :group => ["DATE(created_at)"])

# View
<% @users.each do |user| %>
  <%= user[0] %><br />
  <%= user[1] %>
<% end %>

# Output
2010-01-10 2 
2010-01-08 11
2010-01-07 23
2010-01-02 4

Which is ok, but if no users were created on a given day, it should say "0" instead of not being there at all. How can I loop through each day in the last 30 days and show the count of users created on that day?

Answer 1

date = Date.today-30

# Controller
@users = User.count(:conditions=>["created_at >= ?", date], :order => 'DATE(created_at) DESC', :group => ["DATE(created_at)"])
date.upto(Date.today) do |x|
  @users[x.to_s] ||= 0
end
@users.sort!

# View
<% @users.each do |user| %>
  <%= user[0] %><br />
  <%= user[1] %>
<% end %>