method

sum

rails latest stable - Class: ActiveRecord::Calculations

sum(initial_value_or_column = 0, &block)

public

Calculates the sum of values on a given column. The value is returned with the same data type of the column, 0 if there’s no row. See #calculate for examples with options.

Person.sum(:age) # => 4562

When given a block, loads all records in the relation, if the relation hasn’t been loaded yet. Calls the block with each record in the relation. Returns the sum of initial_value_or_column and the block return values:

Person.sum { |person| person.age } # => 4562
Person.sum(1000) { |person| person.age } # => 5562

Note: If there are a lot of records in the relation, loading all records could result in performance issues.

# File activerecord/lib/active_record/relation/calculations.rb, line 172
    def sum(initial_value_or_column = 0, &block)
      if block_given?
        map(&block).sum(initial_value_or_column)
      else
        calculate(:sum, initial_value_or_column)
      end
    end

sum

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