Group and count in Rails

Question

I know I\'ve seen this before but I can\'t find anything now. I want to group a query by a certain column and be able to display how many are in each group. I got the first part

Answer 1

Just add a :select option:

@line_items = @project.line_items.all(
  :group  => "device_id",
  :select => "device_id, COUNT(*) as count"
)

Then each @line_item will have a count attribute.