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Class: ActiveModel::Type::Decimal

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Subclasses:
ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Decimal, ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Money
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Value
Instance Chain:
self, Helpers::Numeric, Helpers::Immutable, Value, SerializeCastValue
Inherits: ActiveModel::Type::Value
Defined in: activemodel/lib/active_model/type/decimal.rb

Overview

Active Model Decimal Type

::ActiveModel::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

Constant Summary

Helpers::Numeric - Included

NUMERIC_REGEX

Class Method Summary

Value - Inherited

.new

Initializes a type with three basic configuration settings: precision, limit, and scale.

Instance Attribute Summary

Helpers::Immutable - Included

#mutable?

Value - Inherited

#limit, #precision, #scale,
#binary?

These predicates are not documented, as I need to look further into their use, and see if they can be removed entirely.
#mutable?, #serialized?

Instance Method Summary

Helpers::Numeric - Included

#cast, #changed?, #serialize, #serialize_cast_value, #equal_nan?, #non_numeric_string?, #number_to_non_number?

Value - Inherited

#==, #as_json, #assert_valid_value,
#cast

::ActiveModel::Type casts a value from user input (e.g. from a setter).
#changed?

Determines whether a value has changed for dirty checking.
#changed_in_place?

Determines whether the mutable value has been modified since it was read.
#deserialize

Converts a value from database input to the appropriate ruby type.
#eql?

Alias for Value#==.
#hash,
#serializable?

Returns true if this type can convert value to a type that is usable by the database.
#serialize

Casts a value from the ruby type to a type that the database knows how to understand.
#type

Returns the unique type name as a ::Symbol.
#cast_value

Convenience method for types which do not need separate type casting behavior for user and database inputs.
#force_equality?, #map,
#type_cast_for_schema

::ActiveModel::Type casts a value for schema dumping.
#value_constructed_by_mass_assignment?

SerializeCastValue - Included

#initialize, #itself_if_serialize_cast_value_compatible

Constructor Details

This class inherits a constructor from ActiveModel::Type::Value

Instance Method Details

#apply_scale(value) (private)

[ GitHub ] 

  


# File 'activemodel/lib/active_model/type/decimal.rb', line 99



def apply_scale(value)
  if scale
    value.round(scale)
  else
    value
  end
end


  








  

    #cast_value(value)   (private)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/type/decimal.rb', line 59



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


  








  

    #convert_float_to_big_decimal(value)   (private)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/type/decimal.rb', line 83



def convert_float_to_big_decimal(value)
  if precision
    BigDecimal(apply_scale(value), float_precision)
  else
    value.to_d
  end
end


  








  

    #float_precision   (private)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/type/decimal.rb', line 91



def float_precision
  if precision.to_i > ::Float::DIG + 1
    ::Float::DIG + 1
  else
    precision.to_i
  end
end


  








  

    #type  
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/type/decimal.rb', line 50



def type
  :decimal
end


  








  

    #type_cast_for_schema(value)  
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/type/decimal.rb', line 54



def type_cast_for_schema(value)
  value.to_s.inspect
end