Download CSV in rails 3.2 - ruby-on-rails

Question

I am trying to download some model data from a search page to a csv file. Here is the relevant code:
config/application.rb
require 'csv'
controller
def find_by_registration_date
#registration_date = params[:registration_date]
#registrations = Registration.where("DATE(created_at) = ? ", #registration_date)
respond_to do |format|
format.html
format.csv { send_data Registrations.to_csv(#registrations) }
end
end
model
def self.to_csv(options = {})
CSV.generate(options) do |csv|
csv << column_names
all.each do |registration|
csv << registration.attributes.values_at(*column_names)
end
end
end
EDIT: When I try this I get the error:
TypeError in RegistrationsController#find_by_registration_date
can't convert ActiveRecord::Relation into Hash
Rails.root: /home/johnmlocklear/railsApps/nso
Application Trace | Framework Trace | Full Trace
app/models/registration.rb:43:in `to_csv'
app/controllers/registrations_controller.rb:139:in `block (2 levels) in find_by_registration_date'
app/controllers/registrations_controller.rb:137:in `find_by_registration_date'
EDIT: This is so odd. If I do something like:
def find_by_registration_date
#registrations = Registration.order :first_name
respond_to do |format|
format.html
format.csv { send_data #registrations.to_csv }
end
end
...then it works as expected. I'm assuming that one of these methods is returning an array, and another is returning a hash?

Answer 1

Here is what I ended up with...
app/views/registrations/find_by_registration_date.html.erb
<%= link_to 'Export CSV', csv_path(registration_date: #registration_date) %>
routes.rb
match 'csv' => 'registrations#export_csv', :as => :csv
app/controllers/registrations_controller.rb
def export_csv
#registration_date = params[:registration_date]
#registrations = Registration.where("DATE(created_at) = ? ", #registration_date)
csv = CSV.generate do |csv|
csv << ["last_name", "id"]
#registrations.each do |r|
csv << [r.last_name, r.student_id]
end
end
send_data(csv, :type => 'test/csv', :filename => 'add_hoc.csv')
end
Goes against the 'skinny controller/fat model' paradigm, but works for now.