diff options
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index f10c290755..3fc079d84c 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -13,6 +13,12 @@ module ActiveRecord # # Person.count(:age, distinct: true) # # => counts the number of different age values + # + # If used on a +group+, it returns a Hash whose keys represent the aggregated column, + # and the values are the respective amounts: + # + # Person.group(:city).count + # # => { 'Rome' => 5, 'Paris' => 3 } def count(column_name = nil, options = {}) column_name, options = nil, column_name if column_name.is_a?(Hash) calculate(:count, column_name, options) |