Module: FixedPointField

Defined in:
lib/fixed_point_field.rb

Overview

Fixed Point Field specifies that a field that is accessed like a float from a rails script should be stored as an integer in the database. This is only practical when the field always has a fixed number of digits after the decimal place, like how US Dollars have 2 digits of cents after the decimal. More information and examples are available in the README.

Defined Under Namespace

Modules: ClassMethods

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(kls) ⇒ Object

When the module is included, in addition to adding the methods to instances of the class, we need to add methods to the class object, do this with extend.



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# File 'lib/fixed_point_field.rb', line 33

def self.included kls
  kls.send :extend, ClassMethods
end

Instance Method Details

#read_fixed_point(column_name) ⇒ Object

Retrieve the raw value of the field, which will be a Fixnum. This is wrapped behind the default getter, so it is fetched with this function, then down-converted and returned.



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# File 'lib/fixed_point_field.rb', line 61

def read_fixed_point(column_name)
  read_attribute(column_name)
end

#read_floating_point(column_name, width = 2, base = 10) ⇒ Object

Reads the fixed point version and converts. Will return nil if the column value is nil. If you had called: fixed_point_field :price the method price would be a direct call to this function.



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# File 'lib/fixed_point_field.rb', line 69

def read_floating_point(column_name, width = 2, base = 10)
  (rv = read_fixed_point(column_name)) ? (rv.to_f / (base**width)) : nil
end

#set_fixed_point(column_name, value) ⇒ Object

Set a fixed point column to the specificed value (fixed). This is wrapped behind a conversion for the default assignment operator, such that if you had called: fixed_point_field :price the method price= would convert and then call this function.



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# File 'lib/fixed_point_field.rb', line 42

def set_fixed_point(column_name, value)
  write_attribute(column_name, value)
end

#set_floating_point(column_name, value, width = 2, base = 10) ⇒ Object

Set a column using a floating point column. This calls set_fixed_point after it has up-scaled the value to the specified number of digits. By default the width is 2 and base is 10, to work with USD currency. If you had called: fixed_point_field :price the method price= would be a direct call to this function.



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# File 'lib/fixed_point_field.rb', line 53

def set_floating_point(column_name, value, width = 2, base = 10)
  return if value == ''
  set_fixed_point(column_name, (value.to_f * (base**width)).round)
end