instance method `calculate`

Ruby on Rails 4.0.13

Since v3.0.20

Available in: v3.0.20 v3.1.12 v3.2.22.5 v4.0.13 v4.1.16 v4.2.9 v5.2.8.1 v6.0.6 v6.1.7.10 v7.0.10 v7.1.6 v7.2.3 v8.0.4 v8.1.2

Compare with:

calculate(operation, column_name, options = {})

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:

* 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.

* 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.

    values = Person.group('last_name').maximum(:age)
    puts values["Drake"]
    # => 43

    drake  = Family.find_by(last_name: 'Drake')
    values = Person.group(:family).maximum(:age) # Person belongs_to :family
    puts values[drake]
    # => 43

    values.each do |family, max_age|
    ...
    end

Person.calculate(:count, :all) # The same as Person.count
Person.average(:age) # SELECT AVG(age) FROM people...

# Selects the minimum age for any family without any minors
Person.group(:last_name).having("min(age) > 17").minimum(:age)

Person.sum("2 * age")

Parameters

operation req
column_name req
options opt = {}

Source

# File activerecord/lib/active_record/relation/calculations.rb, line 101
    def calculate(operation, column_name, options = {})
      relation = with_default_scope

      if relation.equal?(self)
        if has_include?(column_name)
          construct_relation_for_association_calculations.calculate(operation, column_name, options)
        else
          perform_calculation(operation, column_name, options)
        end
      else
        relation.calculate(operation, column_name, options)
      end
    rescue ThrowResult
      0
    end

Defined in activerecord/lib/active_record/relation/calculations.rb line 101 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveRecord::Calculations

Signature

Parameters