Contents

module AttributePredicates
  module Extensions
    # Adds support for automatically defining predicate methods using +attr_predicate+
    # when defining attributes using +attr+, +attr_reader+, +attr_reader+, and
    # +attr_accessor+.  In comparison to normal Ruby attributes, ActiveRecord
    # predicates use a different system for defining true/false.
    # 
    # == Examples
    # 
    # The predicate methods for attributes use ActiveRecord's type conversion
    # for booleans for determing whether to return true or false.  For example,
    # 
    #   class Person < ActiveRecord::Base
    #     attr_accessor :value
    #   end
    #   
    #   p = Person.new
    #   p.value = false
    #   p.value?    # => false
    #   
    #   p.value = 'false'
    #   p.value?    # => false
    #   
    #   p.value = 'true'
    #   p.value?    # => true
    #   
    #   p.value = 't'
    #   p.value?    # => true
    #   
    #   p.value = 1
    #   p.value?    # => true
    module ActiveRecord
      private
        # For Strings, returns true when value is:
        # * "true"
        # * "t"
        # 
        # For Integers, returns true when value is:
        # * 1
        def attr_predicate(symbol)
          define_method("#{symbol}?") do
            ::ActiveRecord::ConnectionAdapters::Column.value_to_boolean(instance_variable_get("@#{symbol}")) == true
          end
        end
    end
  end
end

ActiveRecord::Base.class_eval do
  extend AttributePredicates::Extensions::ActiveRecord
end if defined?(ActiveRecord)

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
attribute_predicates-0.2.1	lib/attribute_predicates/extensions/active_record.rb
attribute_predicates-0.2.0	lib/attribute_predicates/extensions/active_record.rb