Class: VacuumCleaner::Normalizer

Inherits:
Object
  • Object
show all
Defined in:
lib/vacuum_cleaner/normalizer.rb

Overview

A small base class for implementing custom value normalizers. Might seem like a slight overkill, yet makes the library pretty reusable and all. Works like ActiveModel validators.

class TitleizeNormalizer < VacuumCleaner::Normalizer
  def normalize_value(value)
    value.titelize unless value.blank?
  end
end

class Person
  include VacuumCleaner::Normalizations
  normalizes :name, :titleize => true
end

Any class that inherits from VacuumCleaner::Normalizer must implement a method called normalize_value which accepts the value to normalize. Furthermore the value returned by normalize_value is used as the new value for the attribute.

To reuse the behaviour as defined by the default normalizer (strip & empty), just use super.

class MoreNilNormalizer < VacuumCleaner::Normalizer
  def normalize_value(value)
    value = super
    value = value.downcase if value.respond_to(:downcase)
    %w{0 nil null nul zero nix}.include?(value) ? nil : value
  end
end

If access to the record or attribute being normalized is required the method normalize can be overriden instead.

class FancyNormalizer < VacuumCleaner::Normalizer
  def normalize(object, attribute, value)
    ...
  end
end

When the normalization process is started for an attribute, the method normalize is called with the object, attribute and the value. The default implementation of normalize (as provided by this class) just calls normalize_value.

This can be used together with the normalizes method (see VacuumCleaner::Normalizers#normalizes for more on this).

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Normalizer

Accepts an array of options, which will be made available through the options reader.



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# File 'lib/vacuum_cleaner/normalizer.rb', line 55

def initialize(options = {})
  @options = options
end

Instance Attribute Details

#options ⇒ Object (readonly)

Options as supplied to the normalizer.



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# File 'lib/vacuum_cleaner/normalizer.rb', line 52

def options
  @options
end

Instance Method Details

#normalize(object, attribute, value) ⇒ Object

Only override this method if access to the object or attribute name is required, else override normalize_value, makes life much simpler :)

Default behaviour just calls #normalize_value.



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# File 'lib/vacuum_cleaner/normalizer.rb', line 63

def normalize(object, attribute, value); normalize_value(value) end

#normalize_value(value) ⇒ Object

Override this method in subclasses to specifiy custom normalization steps and magic.

The standard implementation strips the value of trailing/leading whitespace and then either returns that value or nil if it’s empty?.



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# File 'lib/vacuum_cleaner/normalizer.rb', line 69

def normalize_value(value)
  value = value.strip if value.respond_to?(:strip)
  value.nil? || (value.respond_to?(:empty?) && value.empty?) ? nil : value
end