Module: ActiveRecordNullObject::NullObjectSupport::ClassMethods

Defined in:
lib/activerecord_null_object/null_object_support.rb

Instance Method Summary collapse

Instance Method Details

#add_null_object_support(name, options = {}) ⇒ Object

Add null object support to the given accessor method.



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# File 'lib/activerecord_null_object/null_object_support.rb', line 10

def add_null_object_support(name, options = {}) #:nodoc:
  # Determine the class of the association.
  association_class_name = options[:class_name] || name.to_s.classify
  association_class = association_class_name.constantize
  null_class_name = "Null" + association_class_name

  # Determine the null class for this association.
  null_class = options[:null_object].to_s.classify.safe_constantize || null_class_name.safe_constantize

  unless null_class
    # Define the null class as an ancestor of the association class.
    null_class = Object.const_set(null_class_name, Class.new(association_class))
    null_class.class_eval do
      include ::Singleton
      include ::ActiveRecordNullObject::NullObject
    end
  end

  # Modify the "getter" of the relationship to return an
  # instance of the association's null object instead of returning nil.
  class_eval do
    define_method("#{name}".to_sym) do |*args|
      super(*args) || null_class.instance
    end
  end
end

#belongs_to(name, scope = nil, **options) ⇒ Object

Add a :null_object option to belongs_to.



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# File 'lib/activerecord_null_object/null_object_support.rb', line 38

def belongs_to(name, scope = nil, **options)
  # args << options.except(:null_object)
  # Call the real belongs_to so that the association gets defined.
  super(name, scope, **options.except(:null_object))

  # Modify the association if need be.
  if options[:null_object]
    add_null_object_support(name, options)
  end
end

#has_one(name, scope = nil, **options) ⇒ Object

Add a :null_object option to has_one.



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# File 'lib/activerecord_null_object/null_object_support.rb', line 50

def has_one(name, scope = nil, **options)
  # args = options.except(:null_object)

  # Call the real belongs_to so that the association gets defined.
  super(name, scope, **options.except(:null_object))

  # Modify the association if need be.
  if options[:null_object]
    add_null_object_support(name, options)
  end
end