ActiveRecord Schneems Grouping Tutorial Notes

ActiveRecord_Schneems_grouping.mdown

#Grouping#

prods = Product.group(:price).count

Returns

puts prods
=> {573=>3, 574=>4, 575=>6, 576=>4}

The group method returns a hash of all prices, along with the count of each price. For example, there must be 3 items priced at 573

####Grouping is a way for us to get distinct values####

prods = Product.where(:name => "Widget")
prods.count
=> 5

prods = Product.where(:name => "Widget").group(:name)
puts prod
=> [#<Product id: 1,
              user_id: 1,
              name: "HD Electric Amplifier",
              price: 269,
              created_at: "2012-07-07 21:08:22",
              updated_at: "2012-07-09 01:33:57">]

Can also use DISTINCT()

prods = Product.where(:name => "Widget")
prods.count('DISTINCT(name)')
=> 1

Pure Ruby

prods.count(:name, :distinct => true)
=> 1