activemodel/lib/active_model/type/decimal.rb
# frozen_string_literal: true
require "bigdecimal/util"
module ActiveModel
module Type
# = Active Model \Decimal \Type
#
# Attribute type for decimal, high-precision floating point numeric
# representation. It is registered under the +:decimal+ key.
#
# class BagOfCoffee
# include ActiveModel::Attributes
#
# attribute :weight, :decimal
# end
#
# Numeric instances are converted to BigDecimal instances. Any other objects
# are cast using their +to_d+ method, except for blank strings, which are
# cast to +nil+. If a +to_d+ method is not defined, the object is converted
# to a string using +to_s+, which is then cast using +to_d+.
#
# bag = BagOfCoffee.new
#
# bag.weight = 0.01
# bag.weight # => 0.1e-1
#
# bag.weight = "0.01"
# bag.weight # => 0.1e-1
#
# bag.weight = ""
# bag.weight # => nil
#
# bag.weight = :arbitrary
# bag.weight # => nil (the result of `.to_s.to_d`)
#
# Decimal precision defaults to 18, and can be customized when declaring an
# attribute:
#
# class BagOfCoffee
# include ActiveModel::Attributes
#
# attribute :weight, :decimal, precision: 24
# end
class Decimal < Value
include Helpers::Numeric
BIGDECIMAL_PRECISION = 18
def type
:decimal
end
def type_cast_for_schema(value)
value.to_s.inspect
end
private
def cast_value(value)
casted_value = \
case value
when ::Float
convert_float_to_big_decimal(value)
when ::Numeric
BigDecimal(value, precision || BIGDECIMAL_PRECISION)
when ::String
begin
value.to_d
rescue ArgumentError
BigDecimal(0)
end
else
if value.respond_to?(:to_d)
value.to_d
else
cast_value(value.to_s)
end
end
apply_scale(casted_value)
end
def convert_float_to_big_decimal(value)
if precision
BigDecimal(apply_scale(value), float_precision)
else
value.to_d
end
end
def float_precision
if precision.to_i > ::Float::DIG + 1
::Float::DIG + 1
else
precision.to_i
end
end
def apply_scale(value)
if scale
value.round(scale)
else
value
end
end
end
end
end