diff options
Diffstat (limited to 'activerecord/lib')
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 40 |
1 files changed, 20 insertions, 20 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index 69f39e5ba9..ee078102ca 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -78,34 +78,34 @@ module ActiveRecord # This calculates aggregate values in the given column. Methods for count, sum, average, # minimum, and maximum have been added as shortcuts. # - # There are two basic forms of output: + # Person.calculate(:count, :all) # The same as Person.count + # Person.average(:age) # SELECT AVG(age) FROM people... # - # * Single aggregate value: The single value is type cast to Fixnum for COUNT, Float - # for AVG, and the given column's type for everything else. + # # Selects the minimum age for any family without any minors + # Person.group(:last_name).having("min(age) > 17").minimum(:age) # - # * Grouped values: This returns an ordered hash of the values and groups them. It - # takes either a column name, or the name of a belongs_to association. + # Person.sum("2 * age") # - # values = Person.group('last_name').maximum(:age) - # puts values["Drake"] - # # => 43 + # There are two basic forms of output: # - # drake = Family.find_by(last_name: 'Drake') - # values = Person.group(:family).maximum(:age) # Person belongs_to :family - # puts values[drake] - # # => 43 + # * Single aggregate value: The single value is type cast to Fixnum for COUNT, Float + # for AVG, and the given column's type for everything else. # - # values.each do |family, max_age| - # ... - # end + # * Grouped values: This returns an ordered hash of the values and groups them. It + # takes either a column name, or the name of a belongs_to association. # - # Person.calculate(:count, :all) # The same as Person.count - # Person.average(:age) # SELECT AVG(age) FROM people... + # values = Person.group('last_name').maximum(:age) + # puts values["Drake"] + # # => 43 # - # # Selects the minimum age for any family without any minors - # Person.group(:last_name).having("min(age) > 17").minimum(:age) + # drake = Family.find_by(last_name: 'Drake') + # values = Person.group(:family).maximum(:age) # Person belongs_to :family + # puts values[drake] + # # => 43 # - # Person.sum("2 * age") + # values.each do |family, max_age| + # ... + # end def calculate(operation, column_name) if column_name.is_a?(Symbol) && attribute_alias?(column_name) column_name = attribute_alias(column_name) |